Passive Solar HeatingIn CanadaA Discussion Paper

Report ER 79-6

(This research report, including all calculations and illustra-tions, was prepared by Bruce D. Gough, B. Arch, for theConservation and Renewable Energy Branch. The opinionsand conclusions expressed in this publication do not neces-sarily reflect those of the Department of Energy, Mines andResources, Canada.)

Published under the authority ofThe Minister of Energy, Mines and ResourcesGovernment of Canada

Available on request fromConservation and Renewable Energy Branch580 Booth StreetOttawa, OntarioK1A 0E4

Distribution sur demande:Bureau de la conservation et des energies renouvelables580, rue BoothOttawa (Ontario)K1A 0E4

© Minister of Supply and Services Canada 1980Cat. No. M 23-14/79-6ISBN 0-662-10765-9

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ABSTRACT

The purpos e o f thi s pape r i s t o provid e a first-roun d architectural ,technica l an d economi c backgroun d fo r th e discussio n an d implementa -tio n o f passiv e sola r heatin g i n Canada . Despit e th e potentia l o fpassiv e sola r heatin g t o provid e significan t capital , energ y an d main -tenanc e cos t economie s a s compare d t o othe r approache s t o spac e heat -ing , i t ha s no t bee n widel y recognize d no r supporte d i n Canada . Th econclusion s presente d i n thi s pape r fo r th e desig n o f direc t gai n pas -siv e sola r heate d building s couple d wit h hig h level s o f energ y conser -vatio n hav e considerabl e implication s fo r futur e buildin g desig n an dconstructio n i n Canada .

RÉSUMÉ

Le bu t d u présen t documen t es t d'apporte r de s notion s élémentaire sd'architecture , d e technique s e t d'économiqu e à l'étud e e t à l'adop -tio n d e système s d e chauffag e solair e passi f a u Canada . Bie n qu e l echauffag e solair e passi f présent e u n potentie l d'économie s importante sen capital , e n énergi e e t e n entretie n pa r comparaiso n ave c d'autre sméthode s d e chauffag e de s locaux , i l es t pe u conn u e t pe u d'effort s lu iont ét é consacré s a u Canada . Le s conclusion s présentée s ic i relative -ment à l a conceptio n d'édifice s doté s d e système s d e chauffag e solair epassi f a gai n direc t e t a l'adoptio n d'importante s mesure s d'economie sd'énergi e on t un e incidenc e considérabl e su r l a conceptio n e t l a con -structio n futures , d'édifice s a u Canada .

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LIS T OF CONTENTS

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ABSTRACT ii i

1. Summary , Conclusions , Recommendation s 1Resume, Conclusions , Recommandation s 1 2

2. BACKGROUND 2 32. 1 Syste m Nomenclatur e 2 32. 2 Activ e Sola r System s 2 3

3. PASSIV E SOLAR DESIG N 2 73. 1 Genera l 2 73. 2 Generi c Type s 2 8

3.2. 1 Windo w System s 3 03.2. 2 Sunspac e System s 3 53.2. 3 Perimete r Mas s System s 3 7

3.2.3. 1 Mas s Wall s 3 73.2.3. 2 Mas s Roof s 4 0

3.2. 4 Thermosipho n System s 4 13. 3 Synopsi s 4 3

4. HELIOTHERMIC PLANNING 4 74. 1 Buildin g Shap e 4 74. 2 Buildin g Layou t 4 84. 3 Buildin g Orientatio n 4 94. 4 Sit e Plannin g 5 04. 5 Communit y Plannin g 5 5

5. PERFORMANCE 5 95. 1 Genera l 5 95. 2 Technica l Issue s 6 0

5.2. 1 Glazin g - Storag e Sizin g 6 15.2. 2 Effectiv e Therma l Mas s 6 25.2. 3 Therma l Standard s 6 45.2. 4 Mathematica l Modellin g 6 65.2. 5 Technica l Analysi s 7 1

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LIS T OF CONTENTS Cont' d

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6. MATERIAL AND COMPONENT DEVELOPMENT 7 36. 1 Transparen t Insulatio n 7 36. 2 Movabl e Insulatio n 7 76. 3 Hea t Storag e 7 86. 4 Variabl e Shadin g Device s 7 86. 5 Gadgetr y 7 8

7. BUILDIN G STANDARDS 7 97. 1 Genera l 7 97. 2 Leve l 1 8 07. 3 Leve l 2 8 47. 4 Assumption s an d Limitation s 8 67. 5 Benefit s 8 7

APPENDIX A : MOVABLE INSULATIO N DESIG N CRITERI A 9 1

APPENDIX B : NATIONAL PASSIV E SOLAR WINDOW GAI N 9 3

APPENDIX C : TECHNICAL ANALYSI S 9 4

FOOTNOTES AND REFERENCES 10 6

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I . SUMMARY AND CONCLUSIONS

1. Ther e i s a lo w leve l o f awarenes s o f th e concept s an d benefit s o fpassiv e sola r heatin g i n Canada . Th e overwhelmin g thrus t o fgovernmen t an d industr y sponsore d sola r research , demonstratio n an ddevelopmen t programs , an d consequentia l medi a exposure , ha s bee ndirecte d towar d activ e sola r heatin g systems . Contributin g i n par ti s th e lac k o f a descriptiv e an d technica l dat a bod y concernin g th edesig n an d performanc e o f passiv e sola r heate d building s i n th eCanadia n climate .

2. A sola r heatin g syste m i s name d afte r th e natur e o f it s operationa ldynamics . I n a n activ e sola r heatin g syste m energ y i s transporte dvi a a continuousl y pumpe d flui d mediu m requirin g externa l powe rinput . I n a passiv e sola r heatin g syste m energ y flo w occur s pri -maril y vi a th e natura l mode s o f radiation , conductio n an d convec -tion , withou t externa l powe r requirements .

3. A n activ e sola r heatin g syste m emphasize s th e desig n o f discret emechanica l component s t o contai n th e collection , storag e an d dis -tributio n o f sola r energ y independen t o f th e livin g spac e o f th ebuilding . A passiv e sola r heatin g syste m emphasize s th e desig n o fth e buildin g itsel f t o moderat e indigenou s climati c stresse s an dmake th e overal l buildin g fabri c participat e a s a n efficien t sola rcollector . I n orde r t o collec t an d stor e sola r energy , th e storag eand transfe r material s o f a sola r heatin g syste m mus t underg o achang e i n temperature . The n th e challeng e t o passiv e sola r heat -in g i s th e storag e o f sola r hea t gain s an d th e contro l o f natura lheat transfe r withi n th e buildin g fabri c s o a s t o maintai n accep -tabl e comfor t condition s withi n th e livin g spac e o f a building .

4. Ther e ar e fou r generi c type s o f passiv e sola r heating . Windo w an dsunspac e system s allo w sola r radiatio n t o ente r directl y withi n abuildin g whereupo n i t i s absorbe d a s sensibl e heat . Perimete r mas sand thermosipho n system s absor b sola r radiatio n externa l t o th eheate d space , whereafte r i t i s indirectl y admitte d withi n th ebuildin g b y natura l conductio n o r convectio n respectively . I n th edirec t gai n system s wher e bot h sola r collectio n an d storag e occu rwithi n th e livin g spac e larg e quantitie s o f mas s storag e ar erequire d pe r uni t collecto r - windo w are a i n orde r t o maintai ninterna l temperatur e excursion s withi n th e comfor t range . Th eindirec t gai n passiv e sola r system s largel y avoi d th e proble m o findoo r temperatur e contro l b y uncouplin g sola r collectio n fro m th elivin g spac e whic h allow s highe r temperature s an d correspondingl yles s mas s storag e tha n indirec t gai n systems .

5. Whil e som e passiv e thermosipho n system s ar e capabl e o f producin g50° C + ho t wate r an d othe r passiv e sola r syste m type s ar e capabl eof pre-heatin g th e ho t wate r supply , passiv e sola r heatin g system sar e principall y a mean s o f producin g lo w temperatur e hea t fo r spac eheatin g (20-30°C) .

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6. Al l passiv e sola r heatin g system s ar e capabl e o f retrofi t applica -tion s bu t ther e i s insufficien t dat a t o determin e th e relativ efeasibilit y o f alternativ e passiv e sola r retrofi t strategie s o rth e suitabilit y o f th e existin g Canadia n buildin g stoc k fo r pas -siv e sola r retrofit .

7. Th e criteri a o f lo w cost ; owne r appeal ; componen t availability ; an dconstructio n practic e compatibilit y identif y th e direc t gai n type sof passiv e sola r spac e heatin g a s havin g th e highes t feasibilit yfo r widesprea d implementatio n i n ne w residentia l constructio n i nth e nea r term .

8. Passiv e sola r hea t gain s throug h window s ar e intrinsi c wit h th ecreatio n o f an y buildin g an d alread y contribut e significantl y t oth e heatin g energ y requiremen t o f building s i n Canada . Withi n th eexistin g residentia l buildin g stoc k alone , passiv e sola r gain sthroug h window s ar e estimate d t o accoun t fo r 12.5 $ o f th e gros sannua l residentia l heatin g energ y requiremen t o r th e equivalen t o f146. 9 x 10 15J, som e 2.26 % o f th e tota l annua l nationa l energ yconsumption .

9. Th e passiv e sola r heate d buildin g represent s a significan t exten -sio n o f th e desig n principa l tha t for m follow s function . I n addi -tio n t o consideration s o f siting , activit y accomodation , struc -ture , cost , styl e an d s o forth , th e physica l organizatio n o f th epassiv e sola r heate d buildin g depend s upo n it s abilit y t o functio nas a sophisticated , climate-responsiv e therma l syste m whic hcollects , store s an d distribute s sola r energy . Th e lin e o f th ebuildin g result s no t fro m a n arbitrar y acciden t upo n a draftin gboar d bu t fro m a perceptio n tha t eac h par t o f th e building , whil efulfillin g othe r roles , i s als o contributor y withi n thi s energ ysystem . Th e concep t o f passiv e sola r heatin g form s a n energy -consciou s valu e paradig m whic h organize s th e part s o f a building ,yet itsel f integrate s withi n th e fabri c o f existin g buildin g desig ncriteria . Beyon d this , i t i s premature , i f no t entirel y unrealis -tic , t o surmis e tha t th e requirement s o f passiv e sola r heatin g ar eso dominan t a s t o produc e a single-mos t characteristi c passiv esola r buildin g for m o r style .

10. Th e optimizatio n o f passiv e sola r buildin g desig n doe s favour :minima l surfac e are a buildin g enclosures ; th e minimizatio n o f th earticulatio n o f th e exterio r surface s o f th e building , particu -larl y o n th e sout h side , t o preven t lateral-sel f shadin g i n winter ;th e orientatio n o f mos t glazin g withi n + 30° , preferably , an d u pt o 45 ° o f du e south ; an d th e layou t o f activitie s withi n abuildin g i n respons e t o thei r therma l an d daylightin g requirements .

11. I t i s necessar y t o ensur e a minimu m shade-fre e zon e fro m southwar dobject s whic h wil l leav e th e sola r collectio n facilit y o f a passiv esola r heate d buildin g largel y unimpaire d ove r th e heatin g season .Sinc e maximu m shado w length s occu r upo n Decembe r 21st , i t i s sug -geste d a s th e dat e fo r testin g shad e interferenc e whe n th e su n i swithi n 45 ° o f du e south . Howeve r unde r thi s criterio n shado w

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interferenc e distance s increas e wit h increasin g norther n latitud eunti l abov e 49° N Latitude , minimu m residentia l dimension s an dbuilding/sit e coverag e ratios , or , ful l south-wal l sola r exposur ebegi n t o b e compromise d eve n wit h carefu l east-wes t buildin g align -ment . Unles s carefu l consideratio n i s give n t o providin g unshade dsola r exposur e upo n south-facin g wall s i n th e desig n an d layou t o fnew residentia l communities , th e continuatio n o f sola r indiscrimi -nat e communit y plannin g practice s wil l significantl y limi t th eproportio n o f ne w building s amenabl e t o th e us e o f passiv e sola rheating .

12. On a n annua l basis , clear , vertical , south-facin g doubl e an d tripl eglazin g transmi t mor e usabl e sola r energ y tha n outwardl y conduc theat losse s a t al l majo r location s i n Canada ; Th e magnitud e o fbot h th e ne t annua l an d instantaneou s rat e o f ne t sola r gai nthroug h glazin g may b e substantiall y increase d throug h increase si n th e sola r transmittanc e o f glazing ; increase s o f th e therma lresistanc e o f glazin g and/o r th e us e o f movabl e insulatio n ove rglazin g a t night .

13. Whil e revise d standard s hav e recentl y bee n introduce d fo r energ yconservatio n i n ne w Canadia n building s the y contai n n o meaningfu lmeasure s t o ensur e a n overal l therma l standar d fo r a buildin g a sdesigne d an d buil t a s a whole . Mos t conspicuousl y absen t i s astandar d fo r testin g th e ai r tightnes s o f a buildin g whe n close din . Furthermore , significantl y fa r highe r therma l resistanc estandard s fo r th e enclosur e envelop e o f a buildin g ar e show n t o b eeconomicall y commensurat e wit h th e rigour s o f th e Canadia n climate .I t i s a fals e econom y t o accep t sub-optima l energ y conservatio nstandard s a s hig h therma l standard s ar e neve r a s inexpensiv e a swhen the y ar e designe d an d buil t int o a dwellin g uni t fro m th ebeginning .

14. Sinc e th e percentag e contributio n o f passiv e sola r gain s t o th egros s hea t loa d o f a buildin g i s increase d no t onl y b y increasin gth e sout h glazin g are a bu t als o b e decreasin g th e buildin g hea tload , the n th e singlemos t direc t rout e t o cost-effectiv e passiv esola r heatin g i n Canad a lie s throug h hig h therma l standard s o f th ebuildin g enclosur e envelope . When hig h therma l standard s ar eapplie d t o th e buildin g enclosur e th e therma l performanc e o f th ebuildin g become s highl y sensitize d t o variation s i n th e are a an ddistributio n o f glazin g abou t a building , eve n whe n th e tota l are aof th e glazin g i s withi n conventiona l practices .

15. Whil e passiv e sola r heatin g appear s t o b e conceptuall y straight -forward , i t i s thermodynamicall y comple x an d th e developmen t o fmathematica l method s fo r predictin g th e performanc e o f a passiv esola r heate d buildin g remain s a n obstacl e t o th e industry-wid erecognitio n an d applicatio n o f passiv e sola r heating . Traditiona ltechnique s suc h a s th e degree-da y metho d fo r estimatin g th e annua lnet heatin g loa d o f a buildin g ar e inadequat e fo r assessin g th eperformanc e o f passiv e sola r heate d buildings . Whil e mor e appro -priat e methods , includin g hourl y dynami c compute r simulatio n

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program s ar e unde r developmen t b y many researchers , particularl yi n th e Unite d States , thei r accurac y i s unknown . N o standard sexis t b y whic h t o judg e th e relevanc e o f th e content s o f a give nsimulatio n progra m fo r a particula r applicatio n an d fe w program shav e bee n corroborate d b y actua l monitore d data . Furthermor e n ostandard s exis t definin g th e monitorin g o f passiv e sola r heate dbuilding s b y whic h t o determin e whethe r th e monitore d dat a itsel fi s meaningful .

16. Contributin g i n par t t o a lo w leve l o f awarenes s o f passiv e sola rheatin g systems , ther e ar e fe w commercia l proponent s o f passiv esola r buildin g products . Beyon d th e facilitatio n o f passiv e sola rgain s throug h architectura l techniques , furthe r improvement s i n th eefficienc y o f passiv e sola r utilizatio n i s a t leas t a s muc h a pro -ble m o f developin g material s an d component s whos e thermodynami cpropertie s ar e bette r optimize d fo r passiv e sola r performance .These include : transparen t insulation , movabl e insulatio n system sove r glazing , hea t storag e material s an d systems , variabl e shadin gdevices , an d variou s mechanica l device s includin g ai r t o ai r hea texchangers , performanc e monitor s an d s o forth .

17. Mor e researc h i s require d i n orde r t o b e abl e t o prioritiz e th erelativ e cost-effectivenes s o f th e many individua l passiv e sola rand energ y conservatio n strategies . However , i t wa s possibl e t odiscer n th e followin g roug h an d preliminar y rankin g betwee n set sof passiv e sola r an d energ y conservatio n strategies . Th e mos teffectiv e strateg y i s th e relocatio n o f a s muc h o f th e norma l win -dow are a o f a hous e a s possibl e upo n th e sout h wall . Th e second -most effectiv e strateg y i s t o increas e th e therma l specification sof th e buildin g envelop e approximatel y 50 % beyon d thos e recentl youtline d b y th e Nationa l Researc h Council' s Associat e Committe e o nth e Nationa l Buildin g Code . Th e thir d mos t effectiv e i s essen -tiall y a dra w betwee n furthe r increasin g th e energ y conservatio nmeasure s o f th e buildin g an d furthe r increasin g th e sout h windo ware a beyon d redistribution .

18. Whil e i t may tak e year s t o compil e a n extensiv e bod y o f sound ,objectiv e dat a upo n th e desig n an d constructio n o f passiv e sola rheate d building s i n Canada , sufficien t performanc e dat a wa s gener -ate d an d analyse d t o b e abl e t o formulat e a se t o f interi m build -in g standard s fo r th e constructio n o f passiv e sola r heate d build -ing s i n Canad a (se e Sectio n 7 . Buildin g Standards) . Thes e stan -dard s embod y th e cos t effectiv e rankin g o f passiv e sola r an d energ yconservatio n strategie s i n 1 7 above . Th e standard s ar e arrange d i ntwo distinc t level s o f passiv e sola r heating . Th e firs t leve l i sa straightforwar d ite m b y ite m prescriptio n o f minimu m require -ments . B y requirin g goo d therma l standard s an d tha t a t leas t 75 %of a dwelling' s glazin g are a b e south-facing , i t ensure s adequat epassiv e sola r performance . B y limitin g th e are a o f south-facin gglazin g i t doe s no t requir e th e calculatio n o f th e therma lcapacitanc e o f th e buildin g interior . Th e secon d leve l o f th epassiv e sola r standar d i s t o b e applie d wheneve r th e south-facin gwindo w are a o f a buildin g exceed s th e limitin g are a i n leve l one .

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A metho d i s prescribe d t o determin e th e require d therma l capaci -tanc e o f th e buildin g interior , interdependen t wit h th e are a o fsouth-facin g glazin g an d th e therma l standard s o f th e buildin genclosure , i n orde r t o minimiz e overheating .

19. A home buil t t o mee t Leve l On e o f th e Passiv e Sola r Standar d i sshown t o hav e a passiv e sola r heatin g contributio n equa l t o 33 % o fth e gros s annua l heatin g energ y requirement , whic h whe n combine dwit h interna l hea t gain s fro m peopl e an d appliance s reduce s t o 40 %th e proportio n o f th e gros s annua l heatin g energ y requiremen t tha tmust b e supplie d b y th e auxiliar y heatin g system . Furthermor e ahome buil t t o meet Leve l One o f th e Passiv e Sola r Standar d i s show nt o b e highl y cos t effectiv e whe n compare d t o th e sam e buildin g whe nbuil t t o existin g energ y conservatio n standard s wit h uniforml ydistribute d glazing . Whil e th e magnitud e o f heatin g energ y saving swil l var y wit h th e siz e o f th e buildin g an d whil e differen t energ ycos t escalatio n an d discoun t rate s may var y th e financia l analysis ,th e averag e monthl y heatin g energ y cos t saving s ar e estimate d t oexcee d th e additiona l monthl y amortize d cos t o f th e buildin g b y 3. 6times . Thi s i s th e equivalen t o f a rea l annua l rat e o f retur n o nth e margina l investmen t i n th e buildin g o f 14%. I f th e positiv eeffect s o f thes e energ y cos t saving s wer e considere d i n th earrangemen t o f residentia l mortgages , th e purchasin g powe r o f th eprospectiv e homeowne r coul d b e significantl y extended .

20. Abov e an d beyon d th e firs t leve l o f th e Passiv e Sola r Standard ,throug h eve n furthe r increase s i n th e therma l standard s o f th ebuildin g enclosur e envelop e an d i n th e are a o f south-facin g glaz -ing , i t i s indicate d tha t i t may b e possibl e t o al l bu t eliminat eth e consumptio n o f energ y fo r auxiliar y heatin g i n ne w Canadia nresidentia l constructio n an d o n a cost-effectiv e basis . Thi s i s arobus t conclusio n considerin g tha t i t wa s no t attempte d t o asses sth e cos t o f providin g an y additiona l therma l capacitanc e o r hea tstorag e syste m t o absor b passiv e sola r hea t gain s whic h woul d b erequire d b y suc h measures , a s outline d i n Leve l Tw o o f th e Passiv eSola r Standard . However , i n Appendi x C th e performanc e o f 1 0variation s o f th e sam e building , al l exceedin g Leve l On e standards ,wer e examine d an d th e differenc e betwee n th e 2 5 yea r lif e cycl eenerg y cos t saving s an d th e margina l cos t o f furthe r improvin g th ebuildin g wa s consistentl y withi n th e $4,00 0 t o $5,00 0 range , pro -vidin g a broa d margi n fo r th e installatio n o f additiona l therma lcapacit y o n a cost-effectiv e basis .

21. Base d upo n thes e finding s fo r residentia l passiv e sola r heatin g i ti s possibl e t o dra w a broadbrus h conclusio n tha t th e genera lmethod s o f passiv e sola r heatin g ar e equall y viabl e i n al l othe rbuildin g types . Whil e consideration s o f buildin g scale , us e an doccupanc y may var y th e detailin g an d complexit y o f passiv e sola rheat storag e system s withi n a particula r building , th e synerg y o fhighe r envelop e therma l standard s an d south-facin g glazin g i ndisplacin g heatin g energ y consumptio n i s absolute . Additionally ,th e therma l characteristic s o f certai n buildin g type s ac t i n con -cer t wit h passiv e sola r heating . I n building s no t intende d pri -maril y fo r huma n occupanc y suc h a s greenhouse s an d warehouse s th e

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requiremen t o f narrowban d temperatur e contro l may b e somewha trelaxe d simplifying , i n part , th e hea t storag e system . Als o var -iou s plant s an d product s withi n thes e building s doubl e a s therma lstorage . Withi n larg e commercia l an d institutiona l building s i thas alread y bee n establishe d tha t th e rat e o f interna l hea t gain scan b e suc h tha t the y alon e ca n hea t a buildin g i n Canad a whe n i ti s fitte d wit h a hea t pump therma l storag e system . Clearly , pas -siv e sola r hea t gain s may complemen t thi s syste m i n eithe r smalle ror les s intensel y internall y loade d buildings .

22. If , a s i s indicate d i n thi s paper , tha t o n a cost-effectiv e basis ,hig h therma l standard s couple d wit h passiv e sola r heatin g an dtherma l storag e ca n virtuall y eliminat e auxiliar y spac e heatin grequirement s i n residentia l an d commercia l building s i n Canada , i ti s difficul t t o rationaliz e th e necessit y le t alon e th e effective -ness o f an y activ e sola r spac e heatin g system . Whil e dissensio nwithi n th e sola r rank s i s no t desirable , th e questio n o f th e com -parativ e effectivenes s o f th e activ e versu s passiv e approache s t osola r spac e heatin g mus t b e confronte d befor e wha t limite dresource s availabl e fo r sola r spac e heatin g ar e dispose d i n th esustenanc e o f wha t may b e a stillbor n technology .

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RECOMMENDATIONS

A. NEED FOR ACTIO NI n vie w o f th e significan t socia l benefit , vi a heatin g energ ydisplacement , whic h may b e derive d fro m th e broade r applicatio nof passiv e sola r heating , ye t als o recognizin g th e embryoni c stat eof th e ar t o f passiv e sola r heatin g i n Canada , i t i s recommende dtha t th e federa l an d provincia l governments , throug h thei r depart -ments an d agencie s tak e immediat e actio n supportiv e o f th e devel -opment an d implementatio n o f passiv e sola r heatin g i n Canada .

B. SCOPEThe method s o f passiv e sola r heatin g an d th e technique s fo r energ yconservatio n whic h relat e t o th e assembl y o f a buildin g enclosur eenvelop e shoul d b e recognize d an d presente d a s a unifie d field .Bot h ar e mutuall y supportiv e o f th e displacemen t o f heatin g energ yconsumptio n b y th e desig n an d detailin g o f th e buildin g fabri c an dar e clearl y differentiate d fro m th e engineerin g o f mechanica lheatin g systems .

C. EDUCATIONC. 1 Th e firs t ste p t o b e take n i n stimulatin g a deman d fo r passiv e

sola r heate d building s i s t o mak e th e publi c awar e o f wha t passiv esola r heatin g i s an d tha t i t i s effectiv e i n Canada . I t i s recom -mended therefor e t o suppor t th e productio n o f books , pamphlet s an dfilm s whic h describe , communicate , revie w an d illustrat e th e con -cept s an d method s o f passiv e sola r heatin g fo r wid e publi c an dprofessiona l distribution .

C.2 Ther e i s suc h a volum e o f materia l i n thi s stud y tha t no t al l o fi t wil l b e o f interes t t o differen t readers . I t i s recommende dt o divid e thi s stud y int o thre e separat e publications :a) a passiv e sola r prime r fo r th e genera l public , consistin g o f

section s 2 an d 3 ;b) a design , theor y an d guideboo k fo r architects , engineers ,

planner s an d builders , consistin g o f section s 3 , 4 , 5 , 7 an dAppendi x C ; an d

c) a summary , polic y an d progra m brie f consistin g o f section s 1and 7 .

C.3 Suppor t an d publis h a 'sho w an d tell ' surve y o f existin g passiv esola r building s an d passiv e sola r part s o f existin g building s i nCanada. Thi s wil l serv e t o revie w alternativ e passiv e sola rdesig n strategies ; establis h a visua l imag e o f passiv e sola rbuildings ; publiciz e passiv e sola r designer s an d fin d ou t ho wmany passiv e sola r building s ther e ar e i n Canada .

D. STANDARDSD.1 Promot e an d exten d standards , suc h a s thos e outline d i n sectio n 7

fo r th e desig n an d constructio n o f passiv e sola r heate d building si n Canada . Als o designat e th e regulatin g authorit y t o arbitrat ecomplianc e wit h thos e standards .

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D.2 Defin e sola r exposur e requirement s fo r passiv e sola r heate d build -ing s an d promot e zonin g standard s whic h ensur e tha t a n increasin gproportio n o f building s i n ne w communit y developmen t ar e provide dwit h usefu l sola r exposure .

D.3 Defin e standard s fo r th e conten t an d accurac y o f compute r simula -tio n program s o f passiv e sola r heate d buildings .

D. 4 Fro m tim e t o time , a s require d b y changin g circumstance s publis hprojecte d pric e chang e rate s o f conventiona l energ y source s an ddiscoun t rate s t o b e use d i n th e lif e cycl e cos t analysi s o fenerg y conservatio n an d passiv e sola r heatin g i n buildings .

D.5 Defin e standard s fo r th e instrumentatio n an d dat a reductio nmethod s t o b e use d i n th e performanc e monitorin g o f passiv e sola rheate d buildings .

D.6 Defin e a minimu m standar d an d testin g procedur e fo r th e ai rtightnes s o f a buildin g whe n close d in .

E. REMOVAL OF BARRIERS T O IMPLEMENTATIONE. 1 Adjus t deb t servic e rati o limitation s recognizin g th e effec t o f

passiv e sola r hea t gain s an d energ y conservatio n method s i n reduc -in g heatin g energ y cost s an d thereb y exten d th e principa l o f mort -gages an d home improvemen t loans .

E. 2 Discourag e lan d us e policies , communit y plannin g practices , an dzonin g regulation s whic h d o no t requir e sola r acces s i n ne wdevelopment .

F. INCENTIVE S FOR IMPLEMENTATIONF. 1 Recognizin g tha t increase d desig n activit y wil l b e require d t o

provid e a currenc y o f passiv e sola r heate d buildings , conduc t adesig n awar d competitio n fo r passiv e sola r heate d building s i nCanada. Th e vagu e residentia l sectio n o f th e Lo w Energ y Buildin gDesig n Awar d progra m shoul d b e revitalize d wit h consideratio n o fth e following :

a) T o catalyz e implementatio n an d assur e competenc e i t shoul d b erequire d tha t entrie s alread y b e buil t o r prove n tha t eac hwil l b e built .

b) Distinc t categorie s o f award s shoul d exis t fo r singl e uni tresidentia l an d mult i uni t residentia l buildings ; an d t oensur e climat e responsiv e design , award s shoul d als o b e madeby region : Atlantic , Central , Prairie , Pacifi c an d Arctic .

c) I n additio n t o effectiv e sola r performanc e an d lo w auxiliar yenerg y consumption , t o ensur e marke t transferability , th ecriteri a fo r decidin g th e award s shoul d als o includ e simpli -cit y o f construction , cost-effectiveness , an d appearance .

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d) A minimu m o f 5 0 award s shoul d b e made a t a fai r marke t valu efo r eac h desig n o f approximatel y $5,000 .

F. 2 Afte r th e residentia l buildin g desig n award s hav e bee n made asecon d phas e o f passiv e sola r an d energ y conservin g award s shoul dbe implemente d bu t fo r th e desig n an d constructio n o f entir e pas -siv e sola r an d energ y conservin g subdivision s an d communitie srathe r tha n individua l buildings . Thi s wil l ac t a s a positiv e in -centiv e fo r th e large r developer s wh o provid e mos t o f th e service dlot s an d ne w residentia l constructio n i n Canad a an d wil l catalyz eth e layou t o f sola r oriente d communitie s an d th e constructio n o flarg e number s o f passiv e sola r an d energ y conservin g buildings .

F. 3 Implemen t a n ongoin g 'sea l o f approval ' prestig e awar d program .Thi s woul d involve :

a) Th e adoptio n o f standard s fo r passiv e sola r heate d building sas i n sectio n 7 . abov e existin g energ y conservatio n standards ;

b) Presentatio n an d attachmen t o f a graphi c symbo l o r certificat et o a buildin g whic h meet s th e standard ; an d

c) Widesprea d publi c promotio n an d endorsemen t b y credibl e insti -tution s an d agencies .

F. 4 A s a n alternativ e t o E. 1 mak e availabl e mortgage s a t a preferen -tia l rat e o f 1 % fo r th e financin g o f ne w building s whic h mee t o rexcee d th e Passiv e Sola r Standard .

F. 5 Mak e availabl e passiv e therma l home improvemen t loan s o f u p t o$10,00 0 a t a preferentia l rate , fo r th e renovatio n o f existin ghomes u p t o th e leve l o f th e Passiv e Sola r Standard . Upo n com -pletio n an d approva l o f th e work , provid e re-mortgagin g o f th ehome a t a preferentia l rat e o f 1 % extendin g als o th e principa l o fth e mortgag e recognizin g th e increase d valu e o f th e building .

G. DEMONSTRATIONG.1 Suppor t th e constructio n an d demonstratio n o f exemplar y passiv e

sola r heate d building s an d communitie s o f passiv e sola r heate dbuilding s throughou t Canada . Thes e demonstratio n building s coul dbe selecte d fro m winner s o f th e passiv e sola r desig n competitio nand woul d serv e to :

a) ai d i n th e educatio n o f th e public ;

b) provid e constructio n cos t dat a fo r innovativ e therma l an dpassiv e sola r techniques ;

c) provid e corroborativ e performanc e data ;

d) demonstrat e othe r renewabl e energ y an d energ y conservin gmethod s an d products ; an d

e) hav e a domin o effec t upo n designer s an d builders .

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H. RESEARCH AND DEVELOPMENTH.1 Suppor t th e development , documentatio n an d distributio n o f desig n

- interactiv e compute r program s whic h simulat e th e performanc e o fpassiv e sola r heate d buildings .

H.2 Establis h a vigorou s progra m fo r monitorin g th e therma l perfor -mance o f building s includin g no t onl y passiv e sola r hea t gain s bu tals o hea t losse s throug h ai r infiltratio n an d belo w grade .

H.3 Suppor t th e constructio n an d monitorin g o f passiv e sola r tes tcell s i n differen t Canadia n location s t o b e use d i n th e corrobor -atio n o f passiv e sola r compute r simulatio n programs . Thes e sam etes t cell s shoul d als o b e use d t o corroborat e shade d an d non -shade d sola r intensitie s transmitte d throug h glazin g a s predicte dby sola r intensit y an d transmissio n subroutine s withi n compute rprograms .

H. 4 Vigourousl y suppor t th e design , developmen t an d wher e necessary ,th e manufactur e of :

a) alternativ e buildin g assemblie s whic h substantiall y increas eth e resistanc e o f buildin g enclosur e component s t o hea t flo wand ai r infiltratio n i n bot h ne w an d existin g buildings ;

b) hig h sola r transmittanc e glas s an d othe r transparen tinsulations ;

c) movabl e insulatio n systems ;

d) activ e storag e system s whic h coupl e wit h a passiv e sola rheate d space ;

e) ventilate d ai r an d gra y wate r hea t recover y systems ;

f ) passiv e sola r an d othe r buildin g energ y performanc e monitors .

Als o researc h th e cos t - effectivenes s o f th e abov e i n variou sCanadia n location s i n orde r t o establis h thei r relativ e meri t fo rimplementation .

H.5 Suppor t studie s whic h explor e th e feasibilit y o f alternativ e pas -siv e sola r heatin g method s fo r retrofi t application s t o Canadia nbuilding s an d defin e th e necessar y condition s fo r passiv e sola rretrofi t t o differen t buildin g types . The n surve y th e existin gCanadia n buildin g stoc k t o determin e it s suitabilit y an d th emarke t fo r passiv e sola r retrofit .

H.6 Suppor t th e developmen t o f passiv e sola r desig n formula e an dmethod s an d thei r publicatio n a s handbook s fo r professionals .

H. 7 Suppor t th e researc h an d developmen t o f variou s communit y layout st o determin e plannin g an d zonin g regulation s whic h provid e an dmaintai n passiv e sola r access .

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H. 8 Suppor t th e developmen t o f compute r aide d desig n graphi c system swhic h simulat e thre e dimensiona l for m an d sola r shado w patterns .

H. 9 Suppor t studie s t o determin e th e comparativ e durability , effi -cienc y an d extende d lif e cycl e cost-effectivenes s o f activ e an dpassiv e sola r spac e heatin g system s an d t o determine , i f any , th ebes t mi x o f eac h b y locatio n an d climate ; buildin g typ e an dvintage .

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2. BACKGROUND

2. 1 SYSTEM NOMENCLATURETwo genera l approache s t o th e utilizatio n o f sola r energ y fo r spac eheatin g hav e evolved . The y ar e terme d variousl y a s activ e o r passiv esola r heatin g systems . Thi s semanti c differentiatio n stem s fro m dif -ference s i n th e operationa l dynamic s o f eac h syste m i n maintainin g aheate d environment . I n a n activ e syste m therma l energ y i s transporte dby a pumpe d flui d mediu m requirin g externa l powe r input . I n a passiv esyste m therma l energ y flo w i s b y natura l mean s withou t externa l powe rrequirements .

The adoptio n o f thi s nomenclatur e ha s bee n mor e accidenta l tha n over tand consequentl y lack s an y rea l visual , conceptua l o r operationa l pre -cision . Th e tw o approache s ar e perhap s mor e appropriatel y terme dforce d an d natura l sola r heatin g systems . Nevertheles s th e usag e o fan activ e o r passiv e labe l i s alread y widesprea d amon g th e technica lcognoscent i an d i s therefor e appropriat e fo r th e time-being . Howeve rmost people , a t al l public , privat e an d mos t professiona l levels ,make n o suc h differentiatio n betwee n sola r heatin g systems . I n fact ,th e 'conventional ' approach , bot h i n term s o f imag e throug h medi aexposur e an d i n term s o f governmen t sponsore d developmen t an d demon -stration , i s th e activ e sola r heatin g system . Clearl y th e fundamenta lproble m confrontin g passiv e sola r heatin g i s on e o f identit y an d para -doxicall y wit h respec t t o activ e sola r heating . Superficiall y bot har e approache s t o sola r heating , bu t i n term s o f execution , operation ,and appearanc e the y ar e polar . I t i s instructiv e t o identif y passiv esola r heatin g b y contras t wit h activ e sola r heatin g systems .

2. 2 ACTIV E SOLAR SYSTEMSThe desig n inten t o f a n activ e sola r heatin g syste m i s t o thermall yisolate , o r uncoupl e hea t storag e fro m bot h th e outsid e environmen tand th e insid e heate d space . Thi s minimize s hea t los s t o th e outsid eand allow s storag e t o assum e a wid e temperatur e rang e relativ e t o th etemperatur e constan t withi n th e heate d space . Th e overal l effec t o fthi s stratage m i s t o discretiz e th e sola r heatin g syste m int o a se t o fdistinc t component s fo r th e collection , storage , distributio n an d con -tro l o f sola r energy . Collecte d therma l energ y mus t the n b e trans -porte d fro m th e sola r collector s t o th e storag e an d thenc e t o th eheate d space . Thi s i s accomplishe d vi a a continuousl y pumpe d flui d o fliqui d and/o r ai r whic h require s th e inpu t o f mechanica l energ y int oth e system . Currentl y activ e sola r heatin g system s delive r usabl esola r energ y u p t o 1 0 t o 1 2 time s th e amoun t o f activ e energ y inpu trequire d t o operat e th e syste m (2) .

Lik e al l activ e conditionin g systems , b y drawin g fro m a remot e hig henerg y poo l a t will , activ e sola r heatin g system s ar e capabl e o fnarrowban d o r tigh t indoo r temperatur e control . Howeve r th e addi -tiona l advantage s o f suc h activ e sola r heatin g system s d o no t neces -saril y resid e i n overal l energ y delivery , efficiency , reliabilit y o rcos t effectiveness . Moreover , the y li e i n th e fac t tha t a se t o f dis -cret e component s ar e identifie d fo r manufactur e whic h ca n b e inter -face d wit h conventiona l activ e syste m apparatus . Thes e component s ca n

the n b e applie d fro m on e buildin g t o th e nex t wit h littl e o r n o modi -ficatio n t o th e component s themselve s sav e i n term s o f quantity .

The attemp t t o establis h a n activ e sola r component s manufacturin gindustr y shoul d b e recognize d a s th e significan t forc e i n th e research ,development , an d implementatio n o f sola r heatin g t o date .

I t i s frequentl y assume d tha t a sola r heatin g syste m shoul d hav e lo warchitectura l impact . Tha t is , th e solar-heatin g syste m shoul d hav eminima l effec t upo n outsid e appearances , interna l spatia l arrangements ,and occupan t attitude s an d behaviour . Thi s assumptio n uphold s conven -tiona l marketin g sensibilities , whil e neatl y focusin g sola r develop -ment onl y withi n th e building' s mechanica l subsystem . Althoug h tailo rmade fo r activ e systems , activ e sola r heatin g system s onl y partiall yfulfil l thi s prescription . Mos t component s ca n b e hidde n an d d o no taffec t interio r layout . I f th e collector s themselve s wer e mounte dindependentl y o f th e building , whic h i s possible , th e tenan t nee d b eno mor e awar e o f th e natur e o f his/he r syste m tha n a t present . Simpl yset i t an d forge t it . I n practic e though , sola r collector s ar egenerall y mounte d upo n th e buildin g surfac e a t optima l orientatio n an dtilt . Currentl y larg e collecto r array s ar e required , typicall y u p t o50% o f th e floo r are a o f a singl e detache d residence . The y the nbecome th e dominan t visua l an d structura l featur e o f th e buildin g an dunles s interprete d wit h som e sensitivit y becom e idiosyncrati c i nappearance , particularl y i n retrofi t applications .

Technicall y th e problem s confrontin g activ e sola r heatin g system s ar emany. Question s o f durability , leakage , breakdow n an d failur e ar epersistent . Eve n assumin g suc h problem s t o b e solvabl e ove r time , th e

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overwhelming - proble m confrontin g sola r heatin g i n general , an d activ esola r heatin g i n particular , i s on e o f cost-effectiveness . Th e presen twort h o f futur e energ y savings , accounte d b y sola r energ y collecte dand use d ove r th e lif e o f th e system , mus t b e equa l t o o r greate r tha nth e initia l installe d cos t o f th e whol e sola r heatin g system . Th equantit y o f hardwar e an d installatio n labou r embodie d i n th e collec -tion , storage , distributio n an d contro l component s o f a n activ e sola rheatin g syste m i s considerabl y beyon d tha t i n a conventiona l combus -tio n o r resistanc e activ e heatin g system . Thi s inevitabl y result s i nhig h installe d costs , an d make s th e prospec t o f significantl y reduce dcost s throug h mas s productio n o f component s unlikely .

Orgil l (3 ) indicate s tha t activ e sola r heatin g system s ar e no t ye t cos teffective , thoug h assumin g a n oi l cos t escalatio n greate r tha n th egenera l rat e o f inflatio n an d a n installe d syste m cos t o f $190/m 2

collecto r area , a n activ e syste m supplyin g 50 % o f a wel l insulate dsingl e detache d residence' s hea t may b e cost-effectiv e b y 1980 . Cos teffectivenes s may b e reache d soone r fo r lo w ris e multi-uni t building swhic h hav e therma l an d economi c advantage s o f scale . Howeve r recen tfeedbac k o n activ e syste m installe d cost s hav e tende d t o rende r thes econclusion s optimistic . Orgil l no w estimate s installe d activ e sola rheatin g syste m cost s t o b e a t leas t $320/m 2 collector , i n singl edetache d residentia l application s an d beyon d fo r othe r buildin g types .He estimate s thi s t o dela y th e cost - effectivenes s o f activ e sola rheatin g system s som e 5 t o 1 0 year s (4) .

Even wer e th e syste m cost-effectiv e ove r a twenty-yea r life , i t i squestionabl e whethe r th e prospectiv e home buye r woul d accep t th e addi -tiona l $10 K t o $16 K plu s cost . Thi s represent s a constructio n cos tincreas e i n th e orde r o f 2 5 t o 40 % fo r a 10 0 m2 singl e detache d resi -denc e wit h n o increas e i n amenit y o r useabl e space , and , a t a tim e whe nhousin g cost s ar e alread y considere d hig h an d ar e affordabl e onl y t o adeclinin g proportio n o f society .

Predictabl y ver y fe w activ e sola r heatin g system s hav e bee n installe di n Canad a t o date . Ove r th e pas t fe w year s betwee n 5 0 an d 10 0 activ esola r heatin g system s hav e bee n installe d nationall y throug h governmen tsponsore d demonstratio n project s an d a s house s fo r th e wealth y o r avi ddo-it-yourselvers . Thi s compare s wit h a n annua l constructio n rat e o fsome 230,00 0 units . Eve n assumin g a 25 % activ e sola r implementatio nrat e i n 2001 , onl y 5.6 % o f th e tota l ne w dwellin g unit s constructe dbetwee n 197 6 an d 200 1 woul d b e sola r equippe d (5) . Tragicall y th eoverwhelmin g majorit y o f residentia l unit s wil l continu e t o b e buil tlik e th e existin g stock . Tha t is , haphazardl y oriente d t o th e su n an dgenerall y obsolet e wit h respec t t o an y evolvin g mode o f sola r heating ,integra l wit h th e building . Dail y th e magnitud e an d complexit y o f an ysola r retrofi t progra m increases .

Yet th e subjectiv e feasibilit y o f sola r heatin g i s high . Throug h a nopinio n surve y o f th e diffusio n o f activ e sola r technology , Foste r an dSewel l estimat e tha t 20 % o f th e tota l Canadia n residentia l stoc k i n2001 , wil l b e adorne d wit h activ e sola r heatin g system s o f on e kin d o r

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anothe r (6) . Wer e thi s th e cas e i t i s doubtfu l tha t th e linea r devel -opment o f activ e system s wil l multipl y t o suc h proportion s withou tlarg e incentiv e subsidie s o r swifte r conventiona l energ y pric e infla -tion , bot h o f whic h ar e rea l socia l costs .

The evolutio n o f sola r heatin g alread y exhibit s sign s o f a latera lshif t i n technolog y toward s passiv e sola r heating . Du e largel y t o th ehig h cost/hig h ris k problem s o f activ e systems , a numbe r o f passiv esola r heate d privat e residence s ar e planne d o r unde r constructio n i nwidel y scattere d location s i n Canada . A t a recen t sola r conferenc e(7 ) i n Philadelphia , Do n Beattie , Assistan t Secretary , Departmen t o fEnergy , intone d tha t th e entir e U.S . sola r progra m fo r 197 9 i s unde rrevie w fo r a significantl y expande d passiv e component . T o initiat ethi s strategy , h e announce d a passiv e residentia l desig n competitio nand demonstratio n progra m fo r 1978 .

I n s o fa r a s th e evolutio n o f sola r spac e heatin g i s concerned , i tappear s tha t th e longe r peopl e ar e involve d i n activ e systems , th emore the y becom e intereste d i n passiv e sola r heating .

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3. PASSIV E SOLAR DESIG N

3. 1 GENERALHistorically , passiv e sola r heatin g ha s longstandin g root s i n regiona lvernacula r architecture . Prio r t o th e recen t phenomeno n o f activ eheatin g systems , whe n energ y an d technolog y wer e no t s o freel y avail -able , man ha d t o rel y upo n hi s perceptio n o f buildin g for m an d th enatura l therma l propertie s o f loca l material s i n orde r t o achiev e adegre e o f comfor t withi n a buildin g i n a give n climate . Th e consisten tdevelopmen t o f building s wit h thic k adob e o r masonr y wall s i n area s o fhig h diurna l temperatur e rang e i s a classi c exampl e o f vernacula r pas -siv e design . Th e massiv e wall s absor b an d retar d th e hea t o f da y fro menterin g withi n th e buildin g unti l th e nigh t whe n i t i s cooler . Th enet resul t i s a flattenin g o f th e temperatur e variatio n curv e insid eth e building .

Essentiall y th e desig n inten t o f a passiv e sola r heatin g syste m i s t omake th e buildin g itself , rathe r tha n it s mechanica l subsystem , a modu -latin g hea t valv e accepting , retaining , o r rejectin g sola r radiatio n a srequire d b y th e buildin g i n juxtapositio n wit h it s loca l climate . Un -lik e activ e sola r heatin g system s ther e ar e generall y n o discret e o rremot e sola r collector s an d storage/distributio n apparatus . Rathe r th enormal glazing , structura l an d finis h material s o f a buildin g ar e loca -te d s o a s t o doubl e a s element s t o captur e an d stor e sola r radiation .Then, tha t sola r energ y naturall y transmitte d throug h window s and/o rabsorbe d throug h wall s effect s a ne t reductio n i n th e tota l heatin grequiremen t o f th e building . Thi s i n tur n minimize s th e loa d upo n th eback-u p heatin g system , b e i t combustion , resistance , o r activ e solar .

Ther e i s a minimu m relianc e upo n pumpe d fluid s fo r hea t collectio n an ddistribution . Consequentl y ther e i s littl e o r n o mechanica l energ yinpu t t o th e utilizatio n o f th e sola r gain . Th e emphasi s i n hea t dis -tributio n i s upo n natura l radiative , conductiv e an d convectiv e means .However thi s doe s no t preclud e som e activ e energ y inpu t int o a passiv esola r heatin g system , particularl y fo r hea t distributio n vi a ai r circu -lation . Frequentl y passiv e system s utilizin g activ e distributio neithe r fro m th e collectio n o r storag e areas , bu t no t both , ar e terme dhybri d system s a s the y exhibi t bot h activ e an d passiv e characteristics .Belo w i s a matri x o f active , passiv e an d hybri d system s a s determine dby th e operationa l mod e o f thei r collection/gai n an d storage / recover ycycles . (8 )

Storage/recover y cycle :

force d natura l

collection/gai n cycle : force d

natura l

'pure '

activ e

hybri d

hybri d

'pure '

passiv e

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Passiv e sola r heatin g system s offe r grea t potentia l t o reduc e bot hheatin g bill s an d th e mechanica l complexit y o f heatin g system s a s eve na simpl e windo w ca n b e a n efficien t sola r collector . Bu t th e challeng et o passiv e sola r heatin g i s th e storag e o f sola r hea t gain s an d th econtro l o f natura l hea t transfe r s o a s t o maintai n acceptabl e comfor tcondition s withi n a building . Whil e o n th e on e han d huma n comfor tdemands a relativel y constan t indoo r temperatur e th e collectio n an dstorag e o f sola r energ y withi n th e fabri c o f a buildin g require s atemperatur e change . Th e reconciliatio n o f thes e contradictor y desig nrequirement s generate s tw o basi c strategie s fo r th e desig n o f passiv esola r heatin g systems .

Sola r energ y i s eithe r directl y o r indirectl y admitte d withi n a heate dspace .

I n direc t gai n passiv e system s sola r radiation , transmitte d throug hsouth-facin g glazin g i s directl y absorbe d withi n th e buildin g interio rspac e a s sensibl e heat . Sinc e bot h sola r collectio n an d hea t storag eoccu r withi n th e livin g spac e o f th e building , larg e quantitie s o ftherma l storag e mas s ar e require d pe r uni t windo w (o r collector ) are ai n orde r t o kee p interio r temperatur e fluctuation s t o a minimum .

I n a n indirec t gai n passiv e syste m sola r radiatio n i s intercepte d an dabsorbe d externa l t o th e heate d space . Thenc e th e absorbe d therma lenerg y i s eithe r naturall y conducte d throug h mas s storag e t o th eheate d space , o r naturall y convecte d b y a flui d t o hea t storag e and /or th e heate d space . Sinc e sola r collectio n i s remove d entirel y an dheat storag e partl y removed , o r uncoupled , fro m th e livin g spac e i n a nindirec t gai n passiv e system , th e temperatur e variation , withi n th elivin g spac e i s minimize d whil e allowin g wide r temperatur e variatio nand proportionatel y les s mas s o f hea t storag e material s tha n i n adirec t gai n system .

3. 2 GENERIC TYPESDue t o thei r varyin g architectura l an d therma l characteristic s bot hdirec t an d indirec t passiv e system s may b e furthe r subdivide d i n orde rt o identif y generi c type s o f passiv e sola r heating . Howeve r ther e i sconsiderabl e variet y an d overla p i n passiv e sola r heatin g strategies .Thi s ha s le d t o som e confusio n a s t o ho w the y ar e identifie d an d a con -cer n tha t an y classificatio n b e non-restrictiv e (9) . Balcom b ha s iden -tifie d fiv e generi c type s o f passiv e sola r heatin g (10) . A recen tpublicatio n b y th e America n Institut e o f Architect s Researc hCorporatio n converge s si x generi c type s withi n 3 fundamenta l group s(11) . I n thi s paper , a s a furthe r simplification , th e so-calle d iso -late d gai n system s ar e reorganized : th e sunspac e a s a direc t gai nsyste m an d th e thermosipho n a s a n indirec t gai n system . The n bot hdirec t gai n an d indirec t gai n system s ar e eac h subdivide d t o yiel dfou r generi c type s o f passiv e sola r heating : windo w systems ; sunspac esystems ; perimete r mas s systems ; an d thermosipho n systems . Th edescriptiv e aspect s o f thes e fou r generi c type s o f passiv e sola rheatin g ar e summarize d below :

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PASSIVE SOLAR HEATIN G

INDIRECT DIRECT

THERMOSIPHON MASS SUNSPACE WINDOW

Remote Remot e Attache d Integra l

Couple d Couple d Couple d Isotherma l

Convectiv e Conductiv e Radiativ e Radiativ e

Sun Su n Su n Su n

Collectio n Collectio n Spac e Spac e

Storag e Collectio n Collectio n

Storag e Storag e

Storag e

Space

Space

Space

Collection : Spac e

Storage : Spac e

Prim e Therma l Mode

Thermal Sequencin g

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3.2. 1 WINDOW SYSTEMSSola r radiatio n i s directl y admitte d withi n th e heate d livin g spac e o fa buildin g b y sout h facin g fenestration , clerestor y window s an d sky -lights . Upo n strikin g th e surfac e o f an y opaqu e materia l withi n th ebuildin g a portio n o f th e transmitte d sola r radiatio n i s absorbe d an dconducte d int o th e materia l an d adjacen t ai r a s sensibl e heat . I n th eopaqu e materia l a temperatur e wav e i s se t u p whic h move s throug h th emateria l a t a rat e an d diminishin g amplitud e dependen t upo n it s therma ldiffusivity . Th e ai r heate d adjacen t t o th e irradiate d surfac e con -vect s an d alon g wit h th e reflecte d portio n o f inciden t sola r radiatio nand longwav e radiatio n emitte d b y th e directl y heate d materials , dis -tribute s energ y t o thos e area s an d material s no t directl y expose d t osola r radiation .

Diurna l temperatur e contro l i s accomplishe d b y th e absorption , storage ,and carrythroug h o f surplu s daytim e sola r gain s fo r late r releas e a snocturna l heating . Suc h therma l storag e i s provide d b y th e therma lcapacitanc e o f th e interio r finishes , fixture s an d furnishing s locate dwithi n th e livin g spac e o f th e building . Hig h density , hig h conductiv -it y material s stor e mor e heat , mor e quickl y tha n lo w density , lo w con -ductivit y materials . The y ar e therefor e preferre d a s storag e material swhereve r larg e therma l capacitance s ar e require d b y a larg e windo warea . Th e quantit y o f usabl e hea t store d withi n a buildin g depend supon th e amoun t an d typ e o f material s use d a s storage , an d als o upo nth e temperatur e 'head ' attaine d i n thos e storag e materials . Withou t a

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chang e i n temperatur e i n th e storag e materials , surplu s sola r gain scanno t b e store d no r late r released . The n i n a direc t gai n passiv esola r buildin g i t i s necessar y t o allo w th e indoo r temperatur e t o var ybot h u p an d dow n rathe r tha n rigidl y maintai n i t a t a fixe d valu e - t oallo w th e buildin g a s i t were , t o breath e heat .

However a s th e storag e material s ar e locate d withi n th e livin g spaces ,th e rang e o f acceptabl e storag e temperature s ar e generall y limite d t obein g isotherma l wit h thos e require d fo r huma n comfort , tha t i s withi n18 t o 26° C (12) . Suc h a smal l storag e temperatur e rang e implie s tha tdirec t gai n passiv e sola r building s requir e larg e quantitie s o fstorag e materia l pe r uni t collector/windo w a s compare d t o othe r sola rheatin g systems .

Direc t gai n building s sometime s incorporat e a n activ e storag e cycle .

Heate d air , stratifie d a s 'hea t ponds ' nea r ceiling s ca n b e trans -porte d t o othe r room s o r ducte d throug h masonr y cavitie s an d roc kbeds fo r expande d hea t storage . Alternativel y an d fa r mor e 'active 'i n operation , i s th e us e o f a smal l hea t pump t o extrac t direc t sola rheat gain s fro m withi n th e livin g spac e durin g th e da y an d condens eth e hea t withi n a (hot ) wate r storag e tank . A t nigh t ai r ru n throug ha hea t exchange r fe d b y th e ho t wate r storag e i s use d t o hea t th ehouse . B y significantl y expandin g th e storag e temperatur e range , th erequire d storag e volum e i s smal l (13) . Thi s syste m may als o b e use dt o prehea t domesti c ho t water .

I n orde r t o provid e winte r heatin g an d avoi d summer overheatin g wit honl y diurna l hea t storage , a s i s th e cas e wit h mos t passiv e systems ,i t i s necessar y t o admi t sola r radiatio n withi n a buildin g invers e t oth e annua l dail y mean outdoo r temperatur e curve . Tha t is , mos t i nwinte r an d leas t i n summer . Suc h seasona l temperatur e contro l i saccomplishe d largel y b y th e seasona l movement o f th e su n itself . Sinc eth e availabl e intensit y an d transmissio n o f bea m radiatio n ar e bot hfunction s o f th e sola r incidenc e angle , surface s mor e closel y norma lt o th e sun' s ray s bot h receiv e an d transmi t mor e sola r radiatio n tha na surfac e mor e aske w th e sun . The n fo r Canadia n latitude s du e t o th eprogressio n o f th e dail y sola r ar c fro m a lo w altitud e i n winter , t o arelativel y hig h positio n i n summer , vertica l sout h glazin g transmit ssola r radiatio n suc h tha t i t i s maximu m o r nea r maximu m i n winte r an dminimu m i n summer , compare d wit h an y othe r surface . Eve n wer e th esame sout h surfac e tilte d 1 5 t o 30 ° les s tha n vertical , whil ereceivin g marginall y greate r radiatio n i n th e 'deepest ' winte r months ,i t woul d receiv e a s a consequenc e significantl y greate r summer sola rradiation . I n fac t a s th e receivin g surfac e tilt , orientation , o rboth , ar e shifte d awa y fro m sout h vertical , th e annua l dail y sola rintensit y curv e o f th e surfac e progressivel y move s toward s a summermaximum an d winte r minimu m (14) .

Thi s render s low-slop e an d vertica l east/wes t application s o f glazin gpoor choice s fo r optimu m year-roun d passiv e sola r performanc e a s the yinherentl y contribut e t o summer overheatin g an d winte r underheating :opposit e t o a building' s therma l energ y requirement .

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The desirabl e sola r receptio n characteristic s o f sout h vertica l sur -face s ca n b e considerabl y enhance d throug h th e us e o f roo f overhangs ,awnings , horizontally-arrange d vertica l louvre s o r trellises , an d eve ndeciduou s trees . When place d abov e an d befor e sout h window s thes e'shadin g devices ' allo w th e lo w winte r su n virtua l unrestricte d admit -tanc e withi n th e building , ye t increasingl y shad e th e window , unti l i nsummer littl e o r n o bea m radiatio n enter s withi n th e buildin g (15) .

The desirabilit y o f suc h passiv e shadin g device s canno t b e overempha -size d particularl y upo n a buildin g designe d t o b e heate d b y direc tsola r gains . Throug h a hig h leve l o f therma l integrit y th e passiv esola r buildin g i s als o designe d t o kee p hea t in , impartin g i t wit h aheatin g 'balance ' temperatur e fa r lowe r tha n thos e outdoo r tempera -ture s normall y experience d i n Canad a ove r th e summer . Thi s implie stha t no t onl y wil l th e building' s passiv e sola r requiremen t generall ydecreas e a s th e outdoo r temperatur e rise s fro m winte r throug h spring ,but tha t i t wil l ceas e altogethe r fo r a considerabl e perio d o f th esummer. Th e conventiona l alternative s t o summer passiv e shadin g ar eplai n discomfor t o r mechanica l ai r conditionin g whic h i s expensiv e(16) .

Ironicall y onc e th e su n ha s se t th e sam e windo w whic h le t th e sun' senerg y i n conduct s muc h o f i t bac k out , a s a window , eve n whe n doubl eor tripl e glazed , i s generall y th e weakes t poin t o f therma l resistanc ei n th e buildin g envelope . Particularl y upo n a cold , cloud y da y i nmid-winte r eve n a south-facin g windo w ca n b e a ne t lose r o f energy .

However ove r th e lengt h o f th e heatin g seaso n south-facin g doubl e an dtripl e glaze d window s ar e ne t gainer s o f sola r radiatio n a t al l point si n Canad a (17) . I n effec t a south-facin g windo w conserve s mor e heatin generg y ove r th e lon g ter m tha n an y amoun t o f opaqu e wal l insulation .Accordingl y goo d passiv e sola r performanc e ca n b e achieve d throug h th euse o f south-facin g window s alone . Nevertheles s th e therma l resistanc eof doubl e o r tripl e glaze d window s leave s muc h t o b e desired . I f win -dow glazin g significantl y mor e resistan t t o hea t los s wer e t o b e devel -oped th e ne t margi n betwee n sola r gain s an d outwar d hea t losse s coul dbe dramaticall y increased . Bu t a s ye t n o suc h 'transparen t insulation 'i s available . Th e alternativ e i s t o deplo y therma l shutter s an d blind sor othe r form s o f movabl e windo w insulatio n i n orde r t o reduc e outwar dheat losse s a t nigh t an d thereb y increas e th e magnitud e o f th e ne tdail y energ y gai n throug h windows . Fo r mor e Informatio n upo n movabl ewindo w insulatio n system s refe r t o sectio n 6. 2 an d Appendi x A .

Problem s o f glar e may b e experience d o n brigh t winte r day s withi ndirec t gai n passiv e sola r buildings . A wid e variet y o f antiglar estrategie s may b e applie d t o overcom e this , includin g ligh t diffusin gblinds , screen s an d glazings ; th e cultivatio n o f climbin g o r hangin gplant s withi n th e house ; an d th e arrangemen t o f furnitur e s o a s no t t ofac e th e glare . Interio r finishe s shoul d b e selecte d fo r thei r lo wglos s an d fad e resistan t characteristics .

The advantage s o f direc t gai n passiv e sola r heatin g ar e many . Window sar e th e principa l agen t o f sola r collection . The y ar e i n widesprea d

productio n an d ar e o f cours e readil y available . Th e installatio n o fwindow s i s a know n skil l an d componen t o f contemporar y construction .

No massiv e re-educatio n o f th e workforc e i s require d t o implemen tdirec t gai n passiv e sola r heating . Wher e interio r mas s storage , addi -tiona l t o tha t provide d b y conventiona l woo d fram e construction , i srequired , significan t increase s may b e provide d withou t changin g th estructura l mode t o concret e an d masonry . Fo r exampl e th e applicatio nof drywal l may b e doubled ; plaste r may b e adde d t o gypsu m lath ; an dquarr y tile s o r brick s may b e use d a s floo r covering s i n plac e o fcarpets , linoleu m an d wood .

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The advantage s o f direc t gai n passiv e sola r windo w system s ar e no t con -fine d t o technica l points . T o th e homeowner , a sout h facin g windo w i san intimate , comprehensibl e heatin g devic e whic h i s experience d an dnot simpl y intellectualized . Additionally , th e windo w serve s a s apsychologica l an d visua l amenit y t o th e homeowner , doublin g a s th e ey ethroug h whic h th e hous e receive s dayligh t an d hea t an d throug h whic hth e occupan t observe s hi s surroundings . Th e daylightin g rol e o f awindo w ca n b e argue d a s a significan t cos t benefi t wher e i t ca n b eshown t o displac e th e us e o f electrica l lighting .

Direc t gai n passiv e sola r windo w system s ca n b e readil y incorporate d i nth e desig n o f ne w residentia l construction . Sout h facin g window s an dplantin g boxe s may als o b e retrofitte d t o th e existin g housin g stoc kbut ar e restricte d b y a numbe r o f factors . A n unknow n bu t significan tproportio n o f existin g structure s eithe r receiv e littl e wintertim einsolatio n du e t o shadin g fro m southwar d object s o r buildings ; or , d onot hav e a roo m tha t woul d benefi t fro m a n additiona l windo w o n th esouthwar d par t o f th e building .

3.2. 2 SUNSPACE SYSTEMSLik e passiv e sola r windo w systems , sola r radiatio n i s directl y admitte dwithi n th e heate d spac e o f th e buildin g b y sout h facin g window s an dskylights . Unlik e passiv e sola r windo w systems , th e spac e directl yheate d i s no t th e prim e livin g spac e o f th e building . Rathe r th e ter msunspac e refer s t o ancillar y architectura l space s suc h a s greenhouses ,atria , sunrooms , swimmin g poo l enclosures , arcade s an d s o forth , whic har e attache d t o th e principa l livin g spaces .

Dependen t upo n th e us e o f th e sunspace , temperature s may o r may no t b eallowe d t o var y beyon d thos e o f th e prim e livin g spaces . Generall y asunspac e i s partiall y thermall y uncouple d fro m th e livin g spaces .Diurna l an d seasona l temperatur e contro l strategie s ar e accomplishe dsimila r t o thos e discusse d fo r passiv e sola r windo w systems . Tha t is ,(near ) vertica l sout h glazin g fo r optima l yea r roun d sola r penetration ;summer shadin g devices , particularl y whe n th e glazin g i s slope d les stha n vertical ; an d optionall y a therma l shutte r syste m t o moderat enocturna l hea t loss . Whil e th e sunspac e shoul d b e designe d t o stor esufficien t hea t fo r it s ow n nocturna l heating , i t i s als o designe d t osuppl y sola r hea t gain s t o th e prim e livin g space s o f th e building .The wall(s ) interfacin g th e sunspac e t o th e livin g space s may b edesigne d i n a numbe r o f way s t o accomplis h th e desire d therma l coup -ling . Sola r radiatio n may b e directl y transmitte d fro m th e sunspac et o th e livin g space s b y glazing . Damper s o r door s may b e opene d t opermi t natura l convectiv e hea t flo w withi n th e prim e livin g spaces .'Hea t ponds ' particularl y fro m ceiling s o f doubl e o r multi-store ysun space s may b e transporte d vi a a fa n t o th e remainin g buildin g o rroc k storage . Additionall y a massiv e masonr y o r concret e wal l may b eutilize d t o absor b sola r radiatio n withi n th e sunspac e an d conduc ttherma l energ y late r withi n th e building .

A sunspac e may als o b e use d t o convectivel y coo l th e livin g spac e o f abuildin g i n summer b y operatin g a ven t t o th e outdoor s fro m th e to p o f

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th e sunspace . Coo l ai r i s the n draw n throug h th e livin g spac e t oreplac e heate d ai r convecte d ou t o f th e sunspace .

The sunspac e concep t provide s a ric h architectura l sola r vocabular y o fwhic h th e attache d greenhous e i s th e mos t familia r strategy . Alon gwit h freestandin g greenhouse s the y no t onl y provid e passiv e sola r heat -in g bu t als o produc e livin g ornamenta l plants , fruit s an d vegetable saddin g t o thei r rea l worth . Howeve r i t shoul d b e note d tha t th ewidely-use d traditiona l European , lo w gabl e greenhous e i s itsel f helio -thermicall y obsolet e fo r th e Canadia n climate . Thi s i s reflecte d i n

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th e fac t tha t a n averag e o f 26 % o f th e sale s revenu e o f th e Canadia nGreenhous e Industry' s vegetabl e producer s i s spen t upo n fue l cost s(18) . An y improvemen t i n th e viabilit y o f th e greenhous e industr ycoul d ac t t o reduc e th e $150,000,000 + tha t Canadian s spen d annuall yimportin g fres h vegetable s an d cu t flower s (19) .

Whil e i t i s no t th e specifi c tas k o f thi s pape r t o documen t th e devel -opment o f passiv e sola r adapte d greenhouses , significan t decrease s i nheatin g energ y requirement s wil l resul t fro m adaptin g man y o f th epassiv e sola r strategie s discusse d i n thi s paper . (se e als o reference s20, 21 , an d 22) . Thes e possibilitie s hav e no t bee n entirel y los t upo nAgricultur e Canad a whic h ha s recentl y solicite d proposal s t o develo p'sola r adapted ' commercia l scal e greenhouse s (23) . Howeve r n o fundin ghas bee n directe d towar d developin g appropriat e residential-scal eattache d greenhouses .

Whil e servin g th e prim e livin g spac e o f a buildin g a s a sola r collec -tor , a sunspac e serve s th e homeowne r a s a spatia l an d functiona lamenity . Th e facilit y o f growin g ornamenta l plant s o r foo d an d relaxa -tio n withi n th e ambianc e o f livin g foliag e an d sunligh t mak e th e sun -spac e atriu m o r greenhous e eminentl y marketable . Whil e greates ttherma l efficiencie s ar e achieve d b y integratin g a sunspac e withi n th eoveral l buildin g concep t an d envelope , the y may b e considere d a luxur yt o lo w cos t ne w construction . Du e t o th e versatilit y o f direc t gai nsunspac e systems , the y shoul d b e considere d prim e fo r retrofi t appli -cation s t o existin g housing , wher e sufficien t insolatio n i s available .The practicalit y o f th e sunspac e fo r retrofi t i s enhance d b y th e fac ttha t i t i s possibl e t o locat e a sunspac e no t onl y adjacen t t o a nexistin g buildin g bu t als o upo n fla t roofs .

3.2. 3 PERIMETER MASS SYSTEMSSola r radiatio n i s absorbe d b y a storag e mas s o f wate r o r concret e a tth e perimete r o f th e heate d space . Th e absorbe d therma l energ y i s i ntur n naturall y conducte d throug h th e storag e t o late r hea t th e buildin ginterior . Th e type s o f indirec t mas s gai n system s ar e differentiate dby th e positionin g o f th e storag e mass : vertica l i n a sout h facin gwall , or , horizonta l i n a ceilin g o r roof .

3.2.3. 1 MASS WALLSTwo type s o f indirec t gai n mas s wal l passiv e system s ar e i n use .Waterwal l system s us e water , o r th e laten t hea t o f fusio n o f variou ssal t solutions , suc h a s Glauber' s sal t o r calciu m chloride , seale d i ncontainer s fo r therma l storage . Named fo r th e inventors , th eMichel-Tromb e wal l utilize s concret e o r soli d masonr y a s th e hea tstorag e element . Bot h mas s wal l system s ar e positione d behin d vertica lsouth-facin g doubl e glazing . Sinc e th e constructio n o f th e M.I.T .Sola r Hous e I I (24 ) i n 1947 , a considerabl e effor t ha s bee n directe dat understandin g th e behaviou r an d performanc e o f passiv e sola r mas swalls .

As th e sola r collectio n functio n i s remove d fro m th e heate d space , th einterio r temperatur e contro l problem s associate d wit h direc t gai n

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system s ar e largel y avoided . Howeve r thi s strateg y als o locate s th ehighes t temperatur e differenc e directl y a t th e weakes t poin t o f therma lresistance . On sunn y day s th e oute r absorbin g surfac e temperatur e ca ndoubl e th e ambien t roo m temperatur e contributin g t o a hig h rat e o f hea tlos s relativ e t o a windo w alone . Correspondingl y lo w oute r surfac etemperature s a t nigh t partl y compensat e fo r thi s therma l weakness , bu tshutter s externa l t o th e storag e mas s improv e th e performanc e o f verti -cal mas s wal l systems . Nevertheles s Tromb e (25 ) ha s reporte d seasona lefficiencie s ( Q collected/ Q incident ) o f 3 0 t o 35%. Thes e efficiencie scompar e favorabl y wit h th e seasona l performanc e o f activ e sola r heat -in g system s (26) .

Sinc e th e ai r betwee n th e glazin g an d th e vertica l mas s become s heated ,i t i s possibl e t o naturall y convec t thi s ai r t o th e heate d spac e b y th eprovisio n o f damper s a t th e to p an d botto m o f th e mas s storag e wall .

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I n summer , b y closin g th e dampe r a t th e to p o f th e wal l an d openin g on et o th e exterior , i t i s possibl e t o us e th e sam e convectiv e flo w t o dra wai r int o th e buildin g throug h a dampe r o n th e nort h sid e an d convec -tivel y coo l th e building . Otherwis e th e mas s wal l shoul d b e shade d i nsummer i n th e sam e manne r a s direc t gai n systems .

The remova l o f th e sola r absorption/storag e materia l fro m th e buildin ginterio r t o th e buildin g perimete r ha s on e additiona l advantage . B ypresentin g a simpl e two-dimensiona l absorbin g surfac e unshade d fro mfurnishing s o r windo w an d wal l framing , th e accurat e compute r simula -tio n o f th e therma l behavio r o f th e storag e mas s an d buildin g interio ri s greatl y simplifie d a s compare d t o direc t gai n systems . Balcom b o fth e Lo s Alamo s Scientifi c Laboratory , Ne w Mexic o ha s mad e considerabl eprogres s i n understandin g th e behavio r o f mas s wall s throug h compute rsimulation .

I n mas s wal l systems , sola r collectio n are a an d storag e mas s ar e i nconstan t proportion . Balcom b (27 ) indicate s tha t a n optimu m storag emass o f a t leas t 61 3 KJ/ OC-M2 glazin g exist s whic h i s th e equiva -len t thicknes s o f 30 0 mm o f concret e o r 15 0 mm water . Whil e tempera -tur e variatio n o n th e oute r surfac e o f th e mas s may b e ver y large , i ti s th e natur e o f mas s storage , an d i n particula r concrete , t o conduc ta temperatur e wav e o f exponentiall y diminishin g amplitud e t o th e inter -ior . Th e mea n temperatur e variatio n o f th e storag e mas s i s approxi -matel y doubl e tha t o f th e heate d space , a t abou t 1 1 o C (28) . Balcom bals o indicate s tha t th e wate r wal l i s a bette r 'ne t collector ' tha n th econcret e wal l du e t o it s highe r 'effective ' conductivity , whic h mor erapidl y transmit s therma l energ y fro m th e absorbin g surface , resultin gi n lowe r outwar d hea t losses . Thi s may als o lea d t o warme r tempera -ture s o n th e interio r o f a wate r wal l durin g th e daytim e whe n i t maynot b e needed , producin g discomfort .

Throug h furthe r exhaustiv e an d extensiv e dynami c compute r simulatio n o fpassiv e sola r mas s walls , Balcom b ha s develope d simplifie d tabl e an dchar t procedure s whic h ca n b e use d t o calculat e th e sola r contributio nof a wate r o r Tromb e wall , wit h o r withou t nigh t insulatio n (29) .

Whil e indirec t gai n passiv e sola r mas s wal l heatin g system s ar e no t acommon for m o f constructio n assembl y i n Canada , al l require d material sand skill s ar e readil y availabl e fo r thei r fabrication . A s th e wall sar e opaque , inexpensive , translucen t plastic s an d fiberglas s may b eemploye d a s th e glazin g cover . Passiv e sola r mas s wal l system s ar egenerall y applie d t o th e entir e sout h wal l fo r bot h aestheti c an d func -tiona l reasons . Window s ar e forme d b y framin g blank s i n th e mas s wall .Whil e thi s may no t produc e sout h elevation s o f conventiona l appearance ,the y ar e certainl y acceptable . Mos t waterwal l system s ar e no t visuall ypleasin g a s see n fro m th e buildin g interio r unles s th e bottles , cans ,or drum s use d fo r storag e ar e themselve s covere d fro m view .

Unlik e direc t gai n systems , indirec t gai n mas s wal l system s d o no tserv e a s a n outwar d vie w o r spatia l amenit y t o th e occupant . However ,th e mas s wal l syste m particularl y th e Michel-Tromb e type , may doubl e a spar t o f th e structura l an d weathe r claddin g system , whic h shoul d

largel y offse t an y incrementa l cost . Wher e th e southwar d vie w i s unde -sirabl e o r noisy , a s i t may b e ont o a bus y street , passiv e mas s wall sar e mor e appropriatel y use d tha n direc t gai n systems .

I t i s possibl e t o fi t glazin g ove r a n existin g southwar d masonr y wal land thereb y creat e a passiv e sola r mas s wal l heatin g system . U- Vproo f plasti c glazing s simplif y installation , minimiz e breakage , an dkee p cost s dow n a s undistorte d transparenc y i s no t important . Thi sretrofi t techniqu e i s particularl y suite d t o older , bric k o r stone ,soli d masonr y building s o f whic h ther e i s considerabl e numbe r i nEaster n Canada . Suc h wall s ar e frequentl y 30 0 mm thic k providin g ade -quat e therma l capacitance . Howeve r an y cavit y masonr y wal l mus t b efille d wit h grou t i n orde r t o b e effectiv e i n conductin g th e absorbe dsola r gain . Th e feasibilit y o f thi s approac h decrease s wher e th eexistin g wal l i s bric k venee r ove r woo d frame . T o brin g th e wal l t oan equivalenc e o f 30 0 mm concret e i t i s necessar y t o remov e th e inter -io r finis h an d an y insulatio n an d the n instal l considerabl e additiona lmasonry . I n thi s cas e th e sunspac e retrofi t i s decidedl y advantageou sas i t cause s les s interna l disruptio n an d provide s additiona l utilit yand amenit y value .

3.2.3- 2 MASS ROOFSIndirec t gai n mas s roo f system s ar e als o calle d roo f pond s a s generall ythe y consis t o f a pon d o f wate r enclose d i n dar k plasti c lai d upo nhorizonta l meta l ceilings . A horizontall y operate d shutte r syste m i sinstalle d above . I n winte r th e shutter s ar e opene d durin g th e da y t oabsor b sola r radiatio n withi n th e roo f pond . A t nigh t th e shutter sar e close d an d th e store d therma l energ y i s reradiate d downwar d withi nth e heate d space . I n summer th e shutter s ar e opene d a t nigh t an d th eroo f pon d i s coole d b y radiativ e emittanc e t o th e clea r sky . Durin gth e daytim e th e shutter s ar e close d an d th e pon d absorb s hea t fro mwithi n th e house , keepin g i t cool . Th e syste m work s wel l i n th e south -wester n Unite d State s wher e winte r su n angle s ar e relativel y hig h an dclea r skie s facilitat e radiativ e coolin g durin g summer nights . Th eprim e advantag e o f th e syste m i s tha t th e fla t configuratio n o f th eroo f pon d an d shutters , permi t th e hous e t o b e oriente d independen t o fany sola r directiona l constraints . Howeve r th e combinatio n o f a lo wwinte r su n geometr y an d th e occurrenc e o f snowfall s make s thi s for m o findirec t gai n passiv e sola r mas s roo f inappropriat e fo r Canada .

40

The mas s roo f concep t ca n b e adapte d fo r passiv e sola r heatin g i n th eCanadia n climat e throug h th e installatio n o f a roo f gabl e abov e th ehorizonta l roo f pond . Th e southwar d slop e o f th e roo f i s glaze d t oadmi t sola r radiation . Th e nort h slop e i s insulate d an d foil-line d i norde r t o reflec t sola r radiatio n upo n th e roo f pond . Heate d atti c ai rmay als o b e activel y transporte d t o th e prim e livin g spaces .

Withi n th e existin g urba n fabri c th e roofscap e generall y receive s mor econsisten t sola r radiatio n tha n d o walls . Howeve r th e mas s roo f sys -tems hav e lo w retrofi t feasibility . Th e massiv e weigh t o f th e syste mi s to o grea t a loa d fo r mos t existin g woo d fram e ceiling s t o carr y(17 5 kg/m 2 ) . Furthermor e th e syste m require s a highl y conductiv emeta l be d throug h whic h t o bes t conduc t sola r gain s fo r re-radiation .

The applicatio n o f indirec t gai n passiv e sola r mas s roof s t o ne w con -structio n i s limited . Bot h direc t gai n system s an d indirec t gai n mas swal l system s appea r t o b e mor e advantageous , a s the y ad d spatia l o rvisua l amenity ; o r participat e rathe r tha n burde n th e buildin g struc -tura l syste m respectively . Thermall y th e mas s roo f syste m i s a t a dis -advantag e t o othe r passiv e system s a s th e hea t storag e i s locate d i n apositio n wher e i t i s leas t abl e t o naturall y distribut e hea t t o th eremainde r o f th e house .

3.2.1 4 THERMOSIPHON SYSTEMSSola r energ y i s absorbe d externa l t o th e heate d spac e o f a buildin g o na lo w mas s collectio n surfac e heatin g a flui d column , whic h decrease si n densit y an d i s displace d upwar d b y a cooler , heavie r colum n o f th esame flui d enterin g a t th e botto m o f th e collecto r area . Thi s colum ni s i n tur n heate d an d displaced , establishin g a natura l convectiv e loo por thermosiphonin g actio n whic h continue s a s lon g a s th e collecto rsuppl y flui d colum n i s coole r an d heavie r tha n tha t i n th e collector ,or unti l th e flo w i s intentionall y blocke d fo r purpose s o f control .The heate d ai r o r liqui d may b e supplie d directl y t o th e livin g spac eor t o a hea t storag e unit . The n whe n hea t i s require d withi n th elivin g spac e damper s ar e opene d t o allo w convectiv e circulatio n fro mstorag e t o th e spac e an d bac k again .

Once th e su n ha s se t i t i s importan t t o preven t th e coole r colum n o fai r (o r water ) withi n th e collecto r fro m displacin g th e heate d ai r i nth e livin g spac e o r hea t storag e are a causin g hea t loss . Suc h revers ethermosiphonin g i s inhibite d b y locatin g th e livin g spac e an d hea tstorag e are a abov e th e collectio n area . Als o calle d 'u-tube ' design ,thi s layou t ensure s tha t whe n revers e thermosiphonin g start s th e retur ncolum n wil l quickl y becom e th e sam e temperatur e a s i n th e collector ,effectivel y counteractin g th e revers e flo w force . Revers e thermosi -phonin g i s als o prevente d b y th e us e o f damper s an d othe r type s o f flo wrestrictin g valves .

The rang e o f passiv e thermosipho n strategie s i s broad . Thermosiphonin gsystem s hav e lon g bee n use d i n orde r t o hea t domesti c ho t water . Th ecollector s ar e mounte d belo w th e wate r storag e tank . The y ar e smal li n scal e an d may b e fitte d t o bot h ne w an d existin g building s usin g

41

collector s simila r t o thos e i n activ e liqui d systems . Th e heatin g o fhot wate r i s a n importan t featur e o f passiv e thermosipho n system s a sthi s represent s a functio n othe r passiv e system s ar e no t a s abl e t operform .

Site-fabricate d ai r thermosipho n system s fo r spac e heatin g ca n b e buil tint o a house . Thi s require s carefu l therma l plannin g o f th e locatio n o fal l component s an d controls . I n orde r t o operat e th e syste m entirel yby natura l thermosiphonin g an d preven t revers e thermosiphonin g hea tstorag e mus t b e place d abov e th e collecto r area . Similarl y th e sam eheat storag e i s mos t effectivel y locate d beneat h th e heate d spac e i norde r t o naturall y thermosipho n hea t fro m storag e t o th e livin g space .Overal l thi s impose s a stron g vertica l for m determinan t upo n th e desig nof th e building . Thi s proble m i s relieve d b y a n anti-revers e dampe rsyste m allowin g storag e o r th e heate d spac e t o occu r ove r th e sam eheigh t a s th e collectors , o r b y makin g th e syste m hybrid . Tha t is , th ecollectio n storag e cycl e i s force d b y a pump s o tha t storag e may b elocate d bot h belo w th e collectio n are a an d th e livin g spac e o f a buil -ding . Th e locatio n o f storag e abov e th e heate d spac e wit h a n activ estorage : spac e distributio n cycl e engender s a n additiona l se t o f ther -mal an d structura l problem s analogou s t o thos e i n mas s roo f systems .

At presen t a numbe r o f lo w cos t add-o n thermosiphonin g collector s ar ebein g markete d (30 , 31) . The y may b e simpl y tacke d ont o existin g wall swit h hole s punche d a t th e to p an d botto m facilitatin g th e exi t an dentr y o f ai r t o o r fro m th e prim e heate d spac e an d mus t b e fitte d wit h

42

anti-revers e dampers . Th e scal e o f applicatio n i s limite d withou t con -vectio n t o hea t storage , a s otherwis e excessiv e daytim e over-heatin gwoul d occu r withi n th e livin g space . Typicall y a heade r duc t i sattache d t o th e collector s an d th e ai r withdraw n t o hea t storage .

A ne w modular , liqui d thermosiphonin g devic e ha s bee n developed . Eac huni t consist s o f a n integrate d assembl y o f collector , storage , ai rheat exchanger , an d a cleve r oil-layer , non-reversin g passiv e valve .Appropriatel y th e syste m i s terme d a thermic-diod e (32) . I t i s no tyet availabl e a t retail .

I t i s generall y to o earl y t o comment upo n th e effectivenes s o f thes eand othe r passiv e thermosipho n system s a s th e fiel d ha s no t ye t bee nfull y explore d i n term s o f design , applicatio n an d evaluation .Furthe r developmen t i s anticipate d i n th e exploratio n o f attic , ai rthermosipho n collectio n fo r bot h ne w an d retrofi t constructio n (33) ;'hea t pipe ' passiv e collector s utilizin g freo n a s th e workin g flui d(34) ; an d daytim e thermosipho n nigh t tim e shutte r unit s fo r placemen tove r window s (35) .

The thermosiphonin g proces s i s utilize d i n othe r passiv e systems ,particularl y i n th e mas s wal l an d sunspac e concepts , t o eithe r suppl yheate d o r coole d ai r t o th e prim e livin g space . Generall y thoug h i nothe r passiv e system s th e thermosipho n featur e i s secondar y t o othe rmeans o f hea t distribution . An d i n additio n t o thei r sola r heatin gfunction , bot h sunspac e an d mas s wal l system s contribut e spatiall y o rstructurall y t o th e building . Th e passiv e thermosipho n strategie s an ddevice s discusse d i n thi s sectio n ar e use d onl y a s a heatin g system .I n thi s sens e the y bea r a resemblanc e t o activ e system s i n tha t the yconsis t o f a discret e se t o f part s physicall y remove d an d thermall yuncouple d fro m th e livin g space . Whil e thi s ha s th e advantag e o fremovin g th e proble m o f temperatur e contro l fro m th e livin g space ,compare d t o othe r passiv e sola r heatin g systems , thermosipho n system sprovid e n o additiona l visual , spatia l o r structura l valu e t o th e home -owner t o hel p i n discountin g th e syste m cost .

I n summar y thermosipho n system s ar e th e transitiona l zon e betwee nactiv e an d passiv e approache s t o sola r heating . Conceptuall y the yrepresen t th e poin t wher e a passiv e syste m i s n o longe r a n integra lpar t o f th e building . Operationall y the y represen t th e poin t wher e a nactiv e syste m become s passive . Practicall y speakin g whe n a thermosi -phon syste m consist s o f manufacture d modula r collector s thei r develop -ment an d marketin g i s mos t closel y allie d wit h activ e systems .

3. 3 SINOPSI SThe developmen t o f no t onl y othe r passiv e sola r heatin g systems , bu tals o activ e sola r heatin g system s ca n b e viewe d a s a respons e t o th eproble m o f controllin g temperatur e excursion s withi n larg e scal e direc tgai n passiv e systems . T o varyin g degrees , i n al l othe r systems , sola rcollectio n an d storag e ar e uncouple d fro m th e livin g spac e i n orde r t obe abl e t o stor e heat , mor e predictabl y an d i n les s materia l whil eisolatin g th e occupan t fro m temperatur e fluctuation s withi n th e sola r

43

system . However , th e farthe r sola r collectio n an d storag e ar e uncoup -le d fro m th e heate d spac e an d on e another , th e greate r become s th especialize d an d mechanica l natur e o f th e sola r heatin g system , a s th eabilit y t o naturall y distribut e hea t t o th e livin g spac e i s progres -sivel y impaired . Th e followin g tabl e represent s th e rang e o f bot hactiv e an d passiv e sola r heatin g system s a s a continuu m o f increasin gtechnologica l complexity .

ACTIVE PASSIVE

LONG TERM SHORT TERM INDIRECT DIRECT

HIGH TECHNOLOGY

. specia l us e

. independen t o flivin g spac e

. comple x se t o fcomponent s

. annua l storag e

. force ddistributio n

LOW TECHNOLOGY

. mult i us e

. integra l wit hlivin g spac e

. n o uniqu ecomponent s

. diurna l storag e

. natura l

At thi s poin t i n tim e i t i s importan t t o identif y an d pursu e th e imme -diatel y implementabl e aspect s o f sola r heatin g fro m withi n thi s techno -logica l range , eve n i f th e selecte d syste m doe s no t exhibi t th e highes ttheoretica l efficiencies . A 25 % energ y saving s i n al l futur e Canadia nresidentia l constructio n i s mor e significan t i n displacin g non-renew -abl e energie s tha n 100 % saving s o n 10 % o f th e futur e residentia l con -structio n buil t fiftee n year s hence .

44

SOLAR BUILDING-HEATIN G SISTEM S

TRACKING EVACUATED FOCUSSINGFLAT-PLATE THERMOSIPHOH MASS SUNSPACE WINDOW

distributio n

As th e numbe r o f discrete , specialize d component s i n a sola r heatin gsyste m increases , th e immediat e relevanc e o f th e technolog y decreases .First , th e greate r th e system' s numbe r o f component s an d quantit y o fmaterial s no t normall y require d i n th e constructio n o f a building , the nth e greate r i s th e inheren t incrementa l initia l cos t o f th e system .Lower syste m life , lowe r salvag e valu e an d highe r maintenanc e cost sfurthe r ad d t o th e rea l lif e cycl e cost s o f hig h technolog y systems .Second , a s th e syste m dissociate s fro m th e buildin g an d specialize s a sa heatin g syste m only , th e marketabilit y o f th e syste m i s lowered , a si t the n offer s n o qualitativ e o r spatia l amenit y t o th e homeowner ,whic h i s afte r al l wha t home s ar e bough t for . Third , th e creatio n o fspecialize d component s require s considerabl e investmen t an d lea d tim et o establis h bot h a technologica l dat a base , an d a manufacturin g an dmarketin g infrastructur e befor e th e component s an d technolog y ca n b emade generall y available . Finally , eve n whe n th e component s an dtechnolog y becom e available , a considerabl e diffusio n tim e i s require dfo r th e technolog y t o becom e compatibl e (i f a t all ) wit h th e desig nprofession s an d th e construction , installatio n an d maintenanc e trades .

At th e lowe r en d o f th e technologica l continuum , passiv e system sexhibi t hig h implementatio n feasibilit y du e largel y t o th e fac t tha tthei r component s ar e no t a s specialize d a s i n activ e system s an d ten dt o b e integra l i f no t th e sam e a s thos e normall y use d i n a building .The sam e technologica l continuu m carrie s throug h passiv e systems ,implyin g tha t they , themselve s wil l exhibi t varyin g degree s o f imple -mentatio n feasibility . Th e followin g tabl e depict s a passiv e sola rtechnology/en d us e matri x wher e eac h passiv e sola r technolog y wa sassesse d unde r th e fou r criteri a discusse d abov e (lo w cost , owne ramenity , technology/componen t availability , constructio n compatibility )on a simpl e numerica l basis .

More o r les s confirmin g th e tren d o f th e technologica l continuum , th enear ter m feasibilit y o f th e generi c passiv e sola r technologie s i s a sfollows : direc t gai n windo w system s ar e mos t appropriat e fo r spac eheatin g o f ne w residentia l construction ; sunspac e direc t gai n system sar e mos t appropriat e fo r retrofi t spac e heating ; an d thermosipho nsystem s ar e mos t appropriat e fo r domesti c ho t wate r heating .

Thi s doe s no t necessaril y impl y tha t indirec t gai n passiv e systems , i nparticula r th e mas s wal l type , o r eve n activ e system s d o no t hav e som e(eventual ) relevanc e t o Canadia n construction . Thei r us e i s mor eappropriatel y identifie d wit h circumstance s wher e direc t gai n passiv esystem s canno t suppl y a hig h enoug h temperature , a s i n commercia l pro -ces s hea t o r residentia l wate r heating ; wher e th e visua l o r accousti cexterna l environmen t i s objectionable , an d s o forth .

45

46

The balanc e o f thi s pape r focuse s upo n th e furthe r developmen t o f direc t

gai n system s fo r passiv e 'sola r heatin g i n Canada .

DIRECT WINDOW

SUNSPACE

INDIRECT MASS

THERMO-SIPHON

2

2

1

2

1

2

0

1

2

2

2

1

0

2

0

1

8

6

5

2

2

1

2

1

1

2

0

1

1

1

2

2

0

1

0

1

5

7

2

0

1

0

1

0

1

2

2

0

1

0

1

0

1

0

1

2

2

2

5

PASSIVE TECHNOLOGY/END USE FEASIBILIT Y MATRI X

END USE

PASSIVE TECHNOLOGY

SPACE HEATIN G WATER HEATIN G

NEW CONSTRUCTION RETROFIT

KEY CRITERI A VALUE

a - lo w cos tb - owne r amenit yc - technology/componen t availabilit yd - constructio n compatibilit y

0 - poo r1 - som e2 - goo d

a b

c d

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4. HELIOTHERMIC PLANNINGThe seasona l intensit y o f sola r radiatio n i s directionall y dependent .Passiv e sola r heatin g represent s a sophisticate d respons e t o thes edirectiona l sola r phenomen a suc h tha t the y may b e use d t o facilitat erathe r tha n aggravat e huma n comfort . Ther e ar e howeve r a numbe r o fadditiona l 'heliothermic ' aspect s o f buildin g shape , layout , orienta -tio n an d sit e developmen t whic h respon d t o th e directionalit y o f th esun an d overal l therma l efficiency .

4. 1 BUILDIN G SHAPEA revie w o f variou s polyhedra l distortion s reveal s tha t th e les s regu -la r th e enclosur e faces , angle s betwee n faces , an d fac e edg e lengths ,th e highe r th e surfac e are a require d t o enclos e a give n volum e (36) .Sinc e th e abilit y o f a buildin g (o r an y object ) t o los e hea t b y conduc -tio n an d win d infiltratio n ar e bot h function s o f surfac e area , the nfo r a give n interio r volume , th e preferre d buildin g enclosur e woul d b eregula r o r equa l i n al l dimension s (37) .

However , i n orde r t o maximiz e winte r sola r exposur e whil e a t th e sam etim e minimizin g summer sola r exposure , th e shap e o f a buildin g tend st o elongat e upo n it s east/wes t axi s an d shrin k upo n it s north/sout haxis . A t th e sam e tim e th e surfac e are a require d t o enclos e th ebuildin g volum e inherentl y increase s a s th e buildin g i s distorte d fro ma regula r shape . The n th e stretchin g o f a buildin g alon g it s east/wes taxi s t o gai n favourabl e sola r exposur e i s constraine d b y increasin gheat losses . Assumin g orthogona l geometry , optima l east/wes t t onorth/sout h proportion s fo r Canadia n singl e detache d residence s rang efro m slightl y greate r tha n 1: 1 t o 2: 1 (38) .

The surfac e are a t o volum e rati o o f a buildin g i s a robus t measur e o fit s inheren t therma l efficiency . I t i s altere d no t onl y b y th e build -ing' s proportiona l shape , bu t als o b y it s scal e o r relativ e size . Du et o wha t i s generall y terme d th e squared/cube d law , th e volum e o f an yobjec t increase s mor e rapidl y tha n it s surfac e are a a s it s scal e i sincreased . Fo r example , wer e th e scal e o f a cubic-proportione d build -in g doubled , th e outsid e surfac e are a woul d increas e four-fold , bu tth e volum e woul d b e 8 time s a s large . A s note d previously , th e abilit yof a buildin g t o los e hea t i s a functio n o f it s surfac e area . On th eothe r hand , th e volum e o f a buildin g i s a measur e o f th e quantit y o fmateria l an d henc e th e building' s hea t capacity . The n i n simpl e term si t woul d tak e longe r fo r a large r scal e buildin g t o coo l dow n o r hea tup du e t o indoor/outdoo r temperatur e differences , tha n fo r a smalle rscal e building , eve n wer e thei r exterio r fabri c o f identica l therma lproperties . Conversely , increasin g th e therma l resistanc e o f a smal lscal e buildin g woul d provid e i t wit h th e sam e therma l 'tim e constant 'of a large r buildin g (39) .

The volum e o f a buildin g i s als o a measur e o f it s interna l hea t genera -tio n i n a s muc h a s th e occupan t numbe r an d densit y i s generall yincrease d wit h large r buildin g scale . Furthermor e th e penetratio n o fnatura l dayligh t illuminate s onl y th e perimete r area s i n large r build -ings , necessitatin g artificia l lightin g withi n th e buildin g core .

Then a s buildin g scal e i s increased , interna l hea t gain s gro w mor erapidl y tha n th e abilit y o f th e buildin g t o los e heat . I t i s a s aconsequenc e o f thes e therma l advantage s o f scal e tha t durin g th eCanadia n winter , singl e residentia l building s ar e underheate d whil elarge r commercia l building s may b e overheate d (a s i n referenc e 1) .

Spaces whic h projec t outwar d fro m th e genera l perimete r o f a buildin gar e thermall y undesirabl e a s the y exhibi t hig h surfac e are a t o volum echaracteristics , bein g bot h o f smal l scal e an d irregula r t o th e overal lshape . Suc h projection s ar e als o undesirabl e wher e the y may laterall yshad e sout h facin g window s o r an y othe r passiv e collectio n device .Togethe r thes e criteri a constrai n th e articulatio n o f th e exterio rsurface s o f a building . Thi s i s o f particula r concer n i n multi-uni tand townhous e development s wher e th e staggerin g o f unit s i s a commonmetho d o f impartin g visua l identit y an d creatin g privat e outdoo r zone sfo r individua l units .

Where overhang s ar e use d a s a summer shadin g devic e ove r sout h facin gwindow s an d collectio n device s i t i s importan t tha t the y b e designe dsuc h tha t the y d o no t als o shad e mid-winte r bea m insolatio n upo n th e'collectors' . An y windo w o r sola r collectio n devic e lyin g withi n th eshad e o f a n overhan g a t noo n o n Decembe r 21s t i s useles s a s a sola rcollecto r al l year . I n fac t i t i s desirabl e t o exten d th e full yexpose d perio d a mont h eithe r sid e o f Decembe r 21st , b y raisin g th eelevatio n o f th e overhan g relativ e t o th e windo w o r vic e versa .

4. 2 BUILDIN G LAYOUTThermall y th e onl y goo d windo w i n Canad a i s a south-facin g window .However , a s window s ar e als o use d fo r observatio n an d daylightin g i ti s no t practica l t o confin e thei r us e entirel y t o th e sout h elevation .Nevertheless , lik e an y othe r sola r collectio n device , the y shoul d b econcentrate d upo n th e sout h fac e o f a building . Thi s ha s bot h therma land daylightin g implication s upo n th e layou t o f a building . Sedentar yand daytim e activitie s suc h a s living , readin g an d dinin g ar e bes tlocate d upo n th e sout h o f a buildin g a s the y ar e naturall y warme r an dbrighter . Bes t locate d upo n th e nort h sid e o f a residenc e ar e activi -tie s an d space s whic h ar e hea t producing , o f lo w occupancy , o r requir elo w lighting . Thes e includ e space s suc h a s circulation , storage ,garages , workshops , kitche n an d laundr y areas .

The easter n sid e o f a buildin g i s mos t amenabl e t o th e locatio n o fbedrooms , a s i n summer i t ha s th e cooles t evenin g temperature s an dreceive s mornin g brightnes s year-round .

The distributio n o f hea t b y natura l radiativ e an d convectiv e mean sfro m th e sout h t o th e nort h sid e o f a buildin g favour s open-planne dspace s i n th e north/sout h direction . Thi s implie s th e optima lalignmen t o f partition s i s als o north/south . Th e heigh t an d shap e o fceilin g desig n als o pla y importan t role s i n th e entrapmen t and/o rredistributio n o f convecte d hea t gain .

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4. 3 BUILDIN G ORIENTATIO NAs wa s note d i n sectio n 3-2.1 , vertica l sout h facin g surface s receiv esola r radiatio n suc h tha t i t i s (near ) maximu m i n winte r an d minimu mi n summer a s compare d t o an y othe r surfac e slope/orientation . Conse -quentl y mos t sola r collectin g device s ar e oriente d du e sout h a s thi smaximize s ne t collectio n efficiencie s fo r a give n collecto r o r windo warea . Howeve r fo r a numbe r o f reason s i t may no t b e possibl e o rdesirabl e t o orien t a buildin g an d it s passiv e collector s du e south .

- I n som e location s mornin g mis t o r afternoo n clou d may b e a charac -teristi c micro-climati c feature , necessitatin g shiftin g o f th ebuildin g orientatio n westwar d o r eastwar d respectively .

- Olgya y ha s suggeste d tha t orientation s somewha t eas t o f sout h ar epreferre d i n al l climati c zones . Fo r coo l an d temperat e region slik e Canada , h e suggest s orientation s o f 1 2 t o 1 7 degree s eas t o fdue south . Considerin g bot h th e dail y distributio n o f sola r radia -tio n an d outdoo r temperature , thi s produce s th e mos t 'balanced 'heat inpu t an d temperatur e i n a house . Tha t is , th e eas t o f sout horientatio n favour s th e admissio n o f sola r radiatio n i n th e morn -ing s whe n coo l outsid e an d marginall y restrain s sola r admissio nwhen warme r i n th e afternoo n (40) .

- The consideratio n o f vie w fro m a buildin g may favou r it s orienta -tio n awa y fro m du e south . I n th e extrem e case , buildin g site swit h a northwar d vie w ar e i n conflic t wit h th e exposur e require -ment s o f direc t glazin g gai n passiv e sola r heating . However , othe rpassiv e system s may b e incorporate d upo n th e sout h o f a north -oriente d building .

- The existenc e o f latera l shad e producin g tree s o r building s eithe reas t o r wes t o f south , wil l ten d t o orien t th e buildin g awa y fro mdue south , an d awa y fro m th e shadin g object .

- Simila r latera l shad e consideration s an d zonin g set-back s wil lten d t o mak e a sola r buildin g i n (sub ) urba n area s confor m t oexistin g buildin g alignment .

Happil y ther e i s considerabl e toleranc e i n th e orientatio n o f building saway fro m du e south . Fo r example , a t 45 ° N . latitude , ove r th e month sof November , Decembe r an d January , a s a vertica l surfac e i s shifte d15° , 30° , 45° , 60° , 75° , an d 90 ° awa y fro m du e sout h i t lose s 0%, 8%,21%, 35%, 51%, an d 60%, respectivel y o f th e insolatio n upo n a du esout h vertica l surfac e (41) . The n orientation s withi n 30 ° o f du esout h los e almos t negligibl e winte r sola r radiation ; an d losse s fro m30° t o 45 ° o f du e sout h ar e tolerable . Furthe r deviatio n fro m du esout h no t onl y lower s winte r sola r receptio n bu t als o progressivel yimpair s th e facilit y t o provid e passiv e overhea d shadin g t o counte rincrease d summer sola r reception . Accordingl y th e designe r ha s 6 0 t o90° flexibilit y i n solvin g orientation/sitin g problems .

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4. 4 SIT E PLANNINGThe sam e integrativ e consistenc y whic h exist s betwee n a passiv e sola rheatin g syste m an d th e buildin g i t serve s mus t als o exis t betwee n th ebuildin g an d th e environmen t withi n whic h i t operates . I f sola r radi -atio n canno t adequatel y penetrat e an y southwar d trees , othe r build -ings , o r eve n part s o f th e sam e building , th e passiv e sola r heatin gsyste m wil l no t work . The n i n locatin g a sola r buildin g i t i snecessar y t o determin e th e minimu m tolerabl e distance s betwee n th ebuildin g an d an y shadin g object s whic h wil l leav e it s sola r collectio nfacilit y largel y unimpaire d ove r th e heatin g season .

The sola r shado w fro m a n objec t i s readil y modele d t o scale , upo n aheliodon , a n instrumen t whic h simulate s th e geometrica l relationship sbetwee n th e earth' s surfac e an d th e sun , a t an y latitud e an d tim e o fth e year . Otherwis e th e shado w lengt h an d directio n may b e calculate ddirectl y fro m th e sola r altitud e an d azimut h angle s respectively . (42 )

As th e su n rise s i n th e mornin g a n objec t wil l cas t a westwar d shado wof infinit e lengt h whic h progressivel y shrink s a s th e altitud e o f th esun rise s unti l (solar ) noo n whe n th e shado w point s du e nort h an d i s o fminimu m lengt h fo r th e day ; thereafte r th e shado w lengt h increase s an dmoves eastwardl y unti l th e su n set s an d th e shado w i s agai n o f infinit elength .

As th e earth' s declinatio n t o th e su n increase s fro m winte r t o summer ,so bot h th e altitud e o f th e dail y sola r ar c i n th e sk y an d th e sun' sdail y azimutha l movement becom e greater , a t an y give n latitude . A t th ewinte r solstic e th e dail y shado w envelo p fro m a n objec t a t souther nCanadia n latitude s i s boomerang-shaped , it s sunris e an d sunse t arm strailin g approximatel y northwes t an d northeas t respectively . A t th eequino x th e sunris e an d sunse t arm s fal l du e wes t an d eas t respect -ively . A t th e summer solstic e th e shado w envelo p i s agai n boomerang -shape d bu t th e sunris e an d sunse t arm s fal l southwes t an d southeas trespectively .

As locatio n i s move d t o a mor e northerl y latitude , th e sola r altitud ei s lowere d an d th e seasona l differenc e i n dail y azimutha l movementbecomes mor e extreme , until , abov e th e Arcti c Circl e ther e i s n osunris e o n th e winte r solstic e an d n o sunse t o n th e summer solstice .

Bot h th e seasona l an d latitudina l effect s upo n noon-tim e sola r altitud ear e represente d below .altitud e = 90 ° + declinatio n - latitude .As th e earth' s sola r declinatio n varie s fro m +23.45 ° o n th e summersolstic e t o -23.45 ° o n th e winte r solstice , the n clearly , bot h th elowes t sola r altitude s an d longes t northwar d shadow s occu r upo nDecember 21st . A s thi s dat e i s nea r th e middl e o f th e heatin g seaso ni t i s th e logica l tes t dat e fo r determinin g shadow-fre e southwar d sola rexposure . The n du e t o increase d sola r altitud e a t othe r time s o f th eyear , an d th e subsequen t recessio n o f shadow s fro m southwar d objects ,any sola r exposur e upo n a south-facin g surface , a t Canadia n latitudes ,on Decembe r 21s t i s assure d th e remainde r o f th e winte r an d summerunles s intentionall y shade d b y a n overhea d projectio n o r tree .

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Unlik e activ e sola r collector s which , i f necessary , may b e mounte d upo nth e roo f o f a building , mos t passiv e sola r collectio n system s ar e loca -te d upo n th e sout h wal l o f a building . The n i t i s generall y necessar yt o limi t shadin g u p to , bu t no t upo n th e sout h wal l o f a building .However , i t i s no t reasonabl e t o preven t shadin g upo n a sout h wal l ove ran entir e da y a s shadow s ar e o f infinit e lengt h nea r sunris e an d sun -set ; no r i s i t necessar y sinc e th e su n i s o f lo w intensit y a t thes etime s an d furthermor e larg e sola r azimutha l angle s fro m du e sout h i nearl y mornin g o r lat e afternoo n mak e th e sola r incidenc e angl e hig hand sola r intensit y lo w upo n a sout h facin g surface . Sinc e th e sola rtransmittanc e o f mos t glazin g material s decline s rapidl y beyon d inci -denc e angle s o f 45° ; an d becaus e th e quantit y o f sola r radiatio nreceive d upo n a surfac e decline s rapidl y whe n th e receivin g surfac e i soriente d mor e tha n 45 ° fro m du e south , i t i s reasonabl e t o limi t bot hth e latera l shade-fre e are a an d th e bearin g o f a collector/windo w t owithi n + 45 ° o f tru e south . Thi s latera l shade-fre e zon e correspond st o a sola r azimutha l movement o f approximatel y 6 hour s fro m 9 a.m . t o3 p.m . Octobe r throug h March , a t souther n Canadia n latitudes .

Togethe r thes e sola r azimutha l an d altitudina l consideration s defin e acone-shaped , minimu m shade-fre e zon e whic h mus t exis t t o th e sout h o fa passiv e sola r collectin g surface . On Decembe r 21 , an y objec t whic hpierce s throug h th e plan e o f th e sola r altitud e extendin g fro m th e bas eof a sout h facin g wal l an d withi n + 45 ° o f du e sout h violate s th eshade-fre e zone . A shado w fro m a n objec t locate d + 45 ° sout h o f th ebuildin g i s allowabl e provide d i t lie s beneat h th e plan e o f th e sola raltitude . Sinc e th e shado w lengt h fro m a n objec t i s a functio n o f it sheigh t time s th e cotangen t o f th e sola r altitud e angl e the n th e closes ta shad e producin g objec t may approac h a sout h facin g passiv e sola r wal ldepend s upo n it s height . Th e northwar d shado w cas t b y a n object , pe runi t objec t heigh t ar e reviewe d i n Tabl e 2 fo r th e location s an d lati -tude s whic h includ e nearl y al l Canadia n residentia l construction .

Then a t Ottawa , a n objec t 1 0 meter s hig h shoul d no t com e withi n 2 5meter s o f th e axi s o f a du e sout h facin g wall , withi n 45 ° o f th e end sof th e wall . A t Edmonto n th e 1 0 mete r tal l objec t shoul d no t com ewithi n 4 1 meter s o f th e axi s o f a du e sout h facin g wall . A s th ereceivin g surfac e orientatio n i s move d fro m du e south , th e minimu mnormal distanc e fro m th e axi s o f th e sout h wal l t o th e objec tincrease s a s a functio n o f th e su m o f th e sin e plu s cosin e o f th ereceivin g surfac e azimut h angl e fro m du e south .

These shad e fre e zone s ar e genera l an d shoul d b e moderate d b y th efollowin g considerations :

Shadow length s ar e subjec t t o var y o n slope d sites . On sout hslope s the y ar e shorter , o n nort h slope s longer .

-

- The presenc e o f deciduou s tree s an d pole s ar e tolerabl e withi n th eshad e fre e zon e a s the y transmi t mos t o f th e winte r sola r radia -tio n i f fe w i n number .

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LOCATION

HORIZONTAL NORTHWARD SHADOWS, NOON, DECEMBER 21s tSOLAR NORTHWARD SHADOW LENGTH

LATITUDE(°N ) ALTITUD E (° ) PER UNI T OBJECT HEIGHT

TORONTOHAMILTONWINDSOR

43 23. 6 2. 3

OTTAWAFREDERICTONHALIFAX

45 21. 6 2. 5

SUDBURYQUEBECST.JOHN' S

19. 6 2. 8

VANCOUVERWINNIPEGTIMMINS

17. 6 3. 2

CALGARYREGINA

51 15. 6 3. 6

EDMONTONSASKATOON

53 13. 6 4. 1

As latitud e increase s northwardl y th e feasibilit y o f referencin gshado w plannin g t o Decembe r 21s t decreases . A t highe r Canadia nlatitude s sola r radiatio n ca n b e meaningles s a t thi s time , an deve n wher e th e su n jus t rises , shado w length s ove r horizonta l lan dar e unmanageable . Dependen t upo n th e requiremen t o f urba n desig nat thes e latitude s i t may b e necessar y t o limi t th e minimu mshade-fre e envelo p t o tha t o f a mor e southerl y latitude . Whil etendin g t o limi t sola r receptio n upo n a sout h wal l i n December ,th e lengt h o f th e heatin g seaso n i n thes e area s woul d nevertheles sensur e sola r exposur e nearl y identica l t o mor e southerl y latitude sove r th e balanc e o f th e heatin g season .

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These directiona l consideration s o f sola r exposur e an d shadin g favou rth e locatio n o f landscapin g abou t a buildin g suc h tha t i t i s cup -shape d an d openin g towar d th e south . Thi s sam e configuratio n serve sals o t o moderat e th e impunit y o f winte r wind s whic h ten d t o prevai ldurin g clea r weathe r fro m th e west ; durin g storm y weathe r fro m th eeast ; an d t o shif t betwee n th e tw o b y wa y o f th e north .

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The minimizatio n o f wind-pressure d ai r infiltratio n i s a n importan taspec t o f passiv e therma l desig n an d energ y conservatio n a s ai rinfiltration/exfiltratio n i s generall y th e majo r sourc e o f hea t los sfro m a residence , particularl y whe n i t i s wel l insulated . Ai r infil -tratio n throug h crack s aroun d window s an d door s (lamina r flow ) i sroughl y proportiona l t o win d velocit y whil e ai r infiltratio n throug hpore s i n th e remainin g constructio n (orific e flow ) i s roughl y pro -portiona l t o th e squar e o f th e win d velocit y (43 , 44) . Th e presenc eof eart h berms , trees , fences , hedge s an d othe r building s actin g a swindscreen s hav e bee n observe d t o reduc e averag e win d velocitie s som e30 t o 50 % (45 , 46 , 47) . I f ai r infiltratio n i s assume d t o b e on e par tlamina r an d tw o part s orific e a t mea n windspeed s (4- 5 m/s ) whic h i stypical , the n a halvin g o f th e win d velocit y du e t o windbreak s woul dreduc e overal l infiltratio n b y nearl y 66%. Conversel y doublin g th ewin d velocit y b y th e remova l o f a windbrea k woul d increas e ai rinfiltratio n mor e tha n three-fold .

4. 5 COMMUNITY PLANNINGThese heliothermi c principle s ar e relativel y straightforwar d t o imple -ment i n locatin g a sola r heate d buildin g i n rura l an d som e suburba nareas , wher e large , ope n southwar d area s may b e found , o r create d upo nsufficientl y larg e properties . Howeve r mos t residentia l unit s ar ebuil t i n highe r densit y suburba n an d urba n areas , wher e th e goodnes sof fi t betwee n th e shado w fro m on e buildin g t o th e nex t i s critica l i ndeterminin g th e availabilit y o f sola r radiation .

To dat e nearl y al l building s hav e bee n buil t t o alig n wit h thei r stree tfrontages . Olde r stree t grid s i n Canadia n town s an d citie s exhibi tvariabl e an d onl y genera l cardina l orientations , whil e mor e recen t sub -divisionin g practice s hav e favoure d a curvilinear , cul-de-sa c layou tof residentia l streets . Consequentl y many building s lac k a suitabl esouther n wal l orientation , o r wher e thi s doe s exist , sola r exposur emay b e shade d b y othe r building s o r trees . Clearly , i f th e implementa -tio n o f passiv e an d eve n activ e sola r technologie s i s eve r t o becom esignificantl y widespread , i t i s necessar y t o exten d conventiona l plan -nin g an d zonin g criteri a t o includ e heliothermi c sit e plannin g princi -pal s i n th e desig n an d developmen t o f ne w urba n an d communit y buildin gpatterns .

The discussio n o f sola r urba n plannin g and/o r zonin g ha s som e importan tdimension s whic h ar e briefl y outline d below .

The adoptio n o f lan d us e zonin g by-law s o r othe r minimu m plannin g pro -cedure s whic h facilitat e sola r exposur e i s largel y a municipa l rathe rtha n a federa l o r provincia l responsibility . I n thi s respect , munici -pal government s wil l pla y a ke y rol e i n th e widesprea d adoptio n o fsola r technologies , ye t the y may lac k th e mone y o r expertis e t o develo pth e necessar y plannin g o r zonin g procedures .

The discussio n o f sola r exposur e als o bring s t o ligh t th e topi c o fsola r rights . Tha t is , th e lega l technique s whic h may b e use d o rdevise d t o protec t th e futur e sola r acces s o f a sola r heate d buildin g

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fro m shadin g b y subsequentia l buildin g developmen t o r vegetatio n growt hon adjacen t property . I n Ontario , fo r example , n o convenient , legall ysecur e protectio n o f sola r acces s i s availabl e t o a n urba n sola r use r(48) . Howeve r thi s situatio n i s largel y th e resul t o f th e lac k o flega l precedence . Th e sam e referenc e state s tha t restrictiv e covenant si n ne w subdivision s an d 'shad e control ' municipa l by-law s coul d b edevelope d t o protec t sola r access . Clearl y thi s i s a n issue , importan tt o th e lon g ter m securit y o f a sola r development , bu t i t shoul d no t b econfuse d wit h tha t o f planning , designin g an d actuall y providin g sola r

exposur e i n th e firs t plac e - withou t which , th e discussio n o f sola rright s i s largel y academic .

Finall y th e determinatio n o f urba n lan d us e pattern s i s alread y a com -ple x proces s involvin g a myria d o f plannin g board s an d committees , an dbuildin g code s an d by-law s relatin g t o lan d subdivisioning , roa d lay -out , drainage , servicing , emergenc y vehicl e access , parking , buildin gsetbacks , buildin g height , floo r spac e indice s an d s o forth . Some o fthes e practice s may no t quickl y yiel d t o th e principle s o f sola r plan -ning , particularl y wher e th e requiremen t o f sola r exposure , b y limit -in g th e maximu m heigh t o f building s and/o r th e minimu m spac e betwee nbuildings , may limi t th e numbe r o f residentia l unit s o r tota l buildin gare a a develope r may buil d upo n a lan d parcel . I n Davis , California ,wher e a n energ y conservin g an d solar-us e plannin g cod e ha s bee n i neffec t sinc e 1975 , th e majorit y o f builder/developer s wh o initiall yoppose d i t ar e no w supporter s a s residentia l sit e coverag e ha s no tbeen affecte d (49) . Howeve r a t Davis , 38.5° N latitude , winte r shadow sar e shorte r tha n i n Canada . A s ye t i t ha s no t bee n determine d whethe r

and t o wha t degre e sola r exposur e act s a s a constrain t upo n uni t cover -age densitie s a t Canadia n latitudes .

The followin g ar e typica l o f Canadia n residentia l zon e minimu m allow -ances :

feede r roa d allowanc e plu smunicipa l service/sidewal k righ t o f wa y 2 0 m.

frontyar d setbac k 6 m.

maximum buildin g heigh t 1 0 m.

Then acros s a residentia l stree t th e minimu m buildin g t o buildin g di -mensio n i s 3 2 m. Typically , single-detache d residentia l minimu m pro -pert y dimension s ar e 1 5 x 30 m fo r service d lots . Allowin g 9 meter s fo rth e dept h o f a hous e the n approximatel y th e sam e minimu m dimensio n o f30 meter s i s forme d betwee n building s acros s rearyards . The n referrin gt o th e shado w dat a o n pag e 52 , thes e curren t minimu m residentia l allow -ance s d o no t limi t Decembe r 21s t sola r exposur e upo n th e sout h wal l o fdetache d residentia l constructio n u p t o 1 0 meter s o r approximatel y 31/ 2 floor s high , provided :

1) th e locatio n i s no t farthe r nort h tha n 49 ° latitud e (Vancouver ,Winnipeg , Timmins , Cornerbrook) ;

2) th e stree t run s east/west .

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At Edmonton , th e sout h wal l woul d b e shade d u p t o 2 meter s abov e th egroun d o n Decembe r 21s t unless :

1) th e building s wer e locate d upo n a sit e slope d a t leas t 1:1 5 t o th esouth ;

2) th e maximu m residentia l heigh t wa s limite d t o 8 meters ;

3) th e minimu m propert y dimension s wer e increase d t o 1 5 x 3 8 m an dfrontyar d setback s wer e increase d fro m 6 t o 1 0 m.

Of course , development s whic h provid e mor e tha n minimu m propert y dimen -sion s an d setback s an d les s tha n maximu m heigh t woul d provid e increase dlayou t flexibilit y whil e no t impairin g sola r exposure . Unservice d lot sgenerall y requir e a t leas t 135 0 m2 lan d are a pe r residenc e i n orde rt o provid e adequat e are a fo r a septi c tan k an d til e field . I n s o doin gthe y may als o provid e adequat e shad e contro l spac e betwee n buildings .However fo r a variet y o f socia l an d economi c factors , includin g reduce dland , servicin g an d heatin g costs , th e tren d i n residentia l construc -tio n i s towar d low-rise , mediu m an d hig h densit y ro w an d cluste rhousing .

Generall y th e sam e minimu m dimensiona l allowances , outline d above ,appl y t o thi s for m o f residentia l constructio n excep t lo t width s an dsideyar d setback s ar e reduced . Wher e service d b y municipa l feede rstreet s th e sam e minimu m buildin g t o buildin g dimensio n o f 3 2 m i s gen -erate d a s fo r detache d residentia l construction . Howeve r i t i s no t un -common t o fin d frontyar d setback s reduce d b y non-conformin g adjustmen tprocedure s (50) ; o r tha t th e righ t o f wa y allowanc e betwee n unit s i snot designate d a publi c roa d bu t rathe r a private/servic e acces s lan ei n whic h cas e th e lan e an d righ t o f wa y becom e on e an d th e sam e an dar e reduce d t o 7.2 5 m an d frontyar d setback s ar e marginall y extende dt o 9. 2 m (51) . Thi s result s i n a minimu m buildin g t o buildin g distanc eacros s th e lanewa y o f 25. 6 m. Thi s represent s a significan t compromis et o sola r exposur e i n Canada , a s unrestricte d sout h wal l exposur e o nDecember 2 1 i s reduce d t o 45° N latitud e provide d th e stree t run s du eeast/west , unless , a s before :

1) th e building s ar e locate d upo n a sout h slope d site ;

2) maximu m residentia l heigh t i s reduce d fro m 1 0 meters ;

3) minimu m lot , setbac k and/o r roa d allowance s ar e increased .

Ther e ar e o f cours e many alternativ e lan d use/buildin g layou t pattern st o b e explore d othe r tha n th e simpl e model s outline d above . Howeve rth e foregoin g discussio n doe s serv e t o demonstrat e tha t th e provisio nof ful l winte r sola r exposur e i s mor e demandin g fo r passiv e sola r heat -in g system s a s the y generall y requir e ful l sout h wal l exposure . Ye twit h carefu l plannin g o f roa d an d buildin g alignment , ful l passiv esola r exposur e may b e provide d fo r lo w ris e residentia l constructio nat mos t souther n Canadia n latitudes , unde r existin g residentia l lan duse by-laws . Excep t fo r souther n Ontari o an d sout h slopin g site s i n

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th e remainde r o f th e country , th e provisio n o f ful l sout h wal l expo -sur e o n Decembe r 21s t fo r hig h densit y ro w housin g may limi t building /sit e coverag e requirin g eithe r reduce d maximu m height s o r large r build -in g setbacks . I n fac t furthe r stud y i s likel y t o indicat e tha t du e t oth e requiremen t o f sola r exposure , a maximu m sit e coverag e densit yexist s a t a particula r latitud e regardles s o f buildin g height . Th etalle r th e building , th e greate r th e minimu m distanc e require d betwee nbuildings .

Even a t Canadia n latitude s th e adjustment s upo n minimu m residentia ldimensiona l allowance s fo r sola r exposur e ar e no t severe . Howeve r th eprescriptiv e aspect s o f heliothermi c sit e plannin g warrant s mor e exten -siv e developmen t fo r alternativ e location s i f i t i s t o b e widel y consi -dere d a t th e municipa l level . I f lef t unresolve d th e conflic t betwee ncurren t plannin g practice s an d th e requiremen t o f sola r exposur e maybe th e limitin g facto r i n th e widesprea d us e o f sola r technology .Clearl y th e implementatio n o f sola r heatin g i s a design , plannin g an dlega l a s wel l a s a technica l hardwar e problem .

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5. PERFORMANCE

5. 1 GENERALWhen passiv e sola r heatin g i s mentione d a t al l i n Canadia n publication sand article s dealin g wit h sola r energ y i t i s generall y dismisse d a sbein g unsophisticated , o r ineffective . Thes e statement s ar e largel yunfounded . Th e apparen t simplicit y o f a passiv e sola r heatin g syste mi s a s muc h a measur e o f eleganc e a s i t i s o f vulga r unsophisticatio nand th e rea l challeng e t o effectivenes s i s t o d o mor e wit h less .

At firs t glanc e th e us e o f passiv e sola r heatin g i n Canad a i s limite d b yapparentl y lo w level s o f winte r sola r radiation ; a hig h diffus e compon -ent o f tha t radiatio n whic h doe s arrive ; an d th e prevalenc e o f col d win -te r temperature s producin g a lon g heatin g seaso n (52) . Superficiall y i twoul d appea r tha t ther e i s insufficien t usabl e insolatio n t o compensat einherentl y larg e hea t losses . Howeve r a numbe r o f factor s mitigat eagains t thi s myth .

Most maps o f sola r radiatio n intensit y ar e compile d fro m meteorologica lobservation s take n o n a horizonta l surface . Consequentl y lo w sola rintensitie s i n norther n area s ste m largel y fro m th e effec t o f greate rsola r incidenc e angle s wit h increasin g latitude . Precisel y fo r thi sreaso n sola r radiatio n i s no t collecte d upo n a horizonta l surface , bu trathe r upo n a surfac e tilte d anywher e betwee n th e latitud e angl e an dvertica l dependen t upo n th e ter m o f therma l storag e associate d wit h th esystem . Th e apparen t distributio n an d availabilit y o f sola r radiatio nwoul d chang e dramaticall y i f suc h sola r intensit y maps wer e compile d fo rsurface s simpl y tilte d equa l t o thei r latitud e an d mor e s o fo r south -vertica l surfaces .

Afte r collectio n surfac e orientation , th e singl e mos t importan t facto ri n determinin g th e feasibilit y o f sola r heatin g i s th e lengt h o f th eheatin g season . Simply , th e longe r th e heatin g seaso n th e mor e sola rradiatio n i s availabl e t o effectivel y contribut e a s hea t an d amortiz eth e syste m cost .

Finall y a passiv e sola r heatin g syste m collect s an d utilize s al l trans -mitte d inciden t sola r radiatio n n o matte r ho w lo w i n intensity , diffus ei n quality , o r col d th e temperature . Seasonally , thi s largel y compen -sate s fo r highe r hea t los s rate s throug h passiv e systems . A n activ esyste m o n th e othe r hand , require s threshol d radiatio n intensitie s i norde r t o commence collection , resultin g seasonally , i n th e los s o fvas t quantitie s o f potentiall y useabl e sola r radiation , particularl ywhen tha t radiatio n i s predominantl y diffus e instea d o f bea m an d opera -tin g temperatur e differential s ar e larg e (53) .

Sinc e al l building s ar e expose d t o sola r radiation , i t i s inevitabl yabsorbe d i n thei r opaqu e fabri c an d transmitte d a s ligh t throug h ever ywindo w thoug h varyin g i n degre e dependen t upo n orientation . I t follow sthe n tha t al l building s ar e passivel y sola r heate d t o a n extent .Unfortunatel y thes e passiv e sola r gain s i n existin g building s ar elargel y ignore d a s the y occu r naturally . Whil e i t i s possibl e t o d o so ,no fiel d surve y o f th e passiv e sola r componen t i n th e existin g residen -tia l stoc k ha s bee n undertaken .

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However , a recen t stud y (54) , attemptin g t o determin e a ne w balanc etemperatur e fo r us e i n th e degre e da y metho d fo r estimatin g buildin gheat losses , calculate d tha t direc t passiv e sola r gain s accoun t fo r 8t o 16%, dependen t upo n residentia l typ e an d vintage , o f th e gros sannua l heatin g requiremen t o f th e existin g residentia l constructio n i nEaster n Ontario . I n calculatin g th e sola r gain , th e stud y wa s thor -oughl y conservativ e an d assume d tha t windo w orientatio n wa s rando m an dtha t on e thir d o f al l window s wer e completel y shaded . Furthermore ,onl y th e direc t glazin g gain s o f Novembe r throug h Marc h wer e accounted .Interna l gain s fro m huma n respiratio n an d applianc e us e contribute d asimila r percentag e heating . Togethe r bot h direc t passiv e an d interna lgain s accoun t fo r som e 25 % o f th e averag e householder' s potentia lheatin g bill .

Such finding s ar e profoun d t o th e genera l thrus t o f thi s pape r an d t oth e futur e o f passiv e sola r heating . Fo r poin t o f illustratio n i t i sassumed tha t a s i n Easter n Ontario , approximatel y 1/ 8 o f th e nation' sgros s residentia l heatin g requiremen t i s met b y direc t passiv e gains .Then a s calculate d i n Appendi x B passiv e sola r gain s throug h glazin gi n th e residentia l secto r alon e constitute d a quantit y equa l t o 2.26 %of th e tota l nationa l energ y consumptio n o r nearl y fou r time s th etota l nuclea r electri c productio n i n 1975 .

Previousl y i t ha d bee n estimate d tha t al l renewabl e energ y technologie scombine d coul d provid e 3 % o f Canada' s tota l energ y requiremen t i n 199 0(55 , 56) . Ironicall y passiv e sola r heating , whic h currentl y i s proba -bl y th e larges t renewabl e component , ha s bee n omitte d fro m thes e esti -mates , whos e significance , a s a consequence , i s severel y underscored .Bot h nationa l energ y consumptio n statistics , an d mor e importantly ,futur e renewabl e energ y us e scenario s shoul d includ e passiv e sola rheatin g i n thei r reckoning .

Passiv e sola r heatin g i s intrinsi c wit h th e creatio n o f a building .Clearl y th e challeng e i n implementin g passiv e sola r heatin g i s no t i ndeterminin g whethe r a Canadia n buildin g may b e passivel y sola r heated ;but rathe r i n establishin g wha t degre e o f passiv e sola r heatin g may b eachieved .

5. 2 TECHNICAL ISSUE SWhil e sola r hea t gain s throug h glazin g ar e a lon g observe d an d mathe -maticall y wel l understoo d phenomenon , th e natura l absorptio n an d con -tro l o f thes e direc t passiv e gain s withi n th e buildin g fabri c ove r th elengt h o f th e day , i s not . Considerin g th e numbe r o f surfaces ,objects , type s o f materials , an d thermodynami c interaction s withi n th ebuildin g interior , i t i s no t surprisin g tha t t o th e presen t a t least ,th e predictio n o f th e transien t therma l respons e withi n direc t gai npassiv e building s ha s bee n a s muc h a n ar t a s a science .

Overwhelmingly , th e proble m i n applyin g direc t gai n passiv e sola r heat -in g i s th e lac k o f a quantitativ e dat a bas e an d metho d fo r designin g adirec t gai n passiv e buildin g an d predictin g it s performanc e wit h con -fidence . Specificall y monitore d data , simpl e analytica l performanc e

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analytica l performanc e model s an d benefit/cos t studie s ar e neede d t ohel p determin e th e following :

5.2. 1 GLAZIN G - STORAGE SIZIN GThe transmissivit y o f glas s t o sola r radiatio n an d it s resistanc e t oheat flo w i s subjec t t o wid e variatio n dependen t upo n (57) :

- th e sizin g o f glazin g are a wit h respec t t o interna l therma l storag eand overal l hea t load ;

- th e 'effective ' interna l therma l storag e o f a buildin g wit h respec tt o materia l type , locatio n an d configuration ;

- greate r tha n 'minimum ' therma l standard s fo r th e buildin g enclosur eenvelope ; an d

- th e annua l passiv e performanc e o f a buildin g sensitiv e t o glazin garea , effectiv e hea t storag e an d overal l buildin g conductance .

- th e typ e an d thicknes s o f glass ;

-

-

any applie d sola r reflectiv e o r etched , non-reflectiv e coating s(58) ;

any applie d infra-re d reflectiv e o r lo w emissivit y coatings ;

- th e spacin g an d ga s betwee n lights .

To dat e mos t glazin g system s hav e bee n develope d towar d excludin grathe r tha n transmittin g sola r radiation . Consequentl y significan timprovement s i n bot h sola r transmittanc e an d therma l resistance , whic har e possibl e throug h th e rationa l applicatio n o f th e abov e strategies ,have ye t t o b e widel y applied . Nevertheless , i t wa s establishe d i n1947 tha t ove r th e lengt h o f th e heatin g season , clear , vertica l sout hfacin g doubl e glazin g gain s mor e sola r radiatio n tha n i t outwardl yconduct s heat , a t al l continenta l location s i n th e U.S.A . (59) . Thi sphenomenon ha s bee n largel y corroborate d i n Canad a b y Coope r (60) ,Gilpi n (61 ) Goug h (62 ) an d Jone s (63) . Mitala s (64 ) indicate s tha tth e ne t heatin g seaso n gai n o f vertical , south , doubl e glazin g i nCanada average s 5 0 kWh/m 2. I n movin g t o tripl e glazin g a 33 %reductio n i n outwar d therma l conductanc e mor e tha n compensate s fo r a10—15% reductio n i n sola r transmissio n resultin g i n a n averag e ne theatin g seaso n gai n o f 10 0 kWh/m 2 i n Canada .

However , th e simpl e applicatio n o f larg e sout h facin g area s o f glazin gdoes no t necessaril y ensur e lo w heatin g bills . Muc h o f th e sola r gai nof sout h window s occur s upo n clea r day s o f hig h sola r irradiance , whe nth e daytim e ne t sola r gai n i s highes t an d cause s th e maximu m tempera -tur e excursio n withi n th e buildin g an d storag e materials . Bu t th erang e o f interio r temperature s i n direc t gai n passiv e sola r building si s limite d b y huma n comfor t requirements , generall y fro m 1 8 t o 26°C . I nfac t i t i s customar y i n th e analysi s o f passiv e sola r building s t o

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restric t th e maximu m indoo r temperatur e rang e t o 6° C (10°F) . Belo w th eminimu m setpoin t temperatur e hea t i s supplie d an d abov e th e maximu msetpoin t temperatur e hea t i s removed . The n insufficien t hea t storag et o absor b surplu s direc t gain s throug h glazin g o n clea r winte r day swithi n th e prescribe d comfor t rang e wil l caus e overheating . An y over -heatin g i s vente d awa y leavin g th e correspondin g windo w are a onl y a s anocturna l therma l liability . Consequentl y decrease s i n th e annua l hea tloa d o f a buildin g ar e linea r wit h increase s i n th e sout h glaze d are aonl y i f parallele d b y increase s i n th e interna l hea t storag e o f abuilding . I n orde r no t t o wast e sola r gain s throug h glazin g i t i simperativ e t o b e abl e t o siz e th e interna l hea t storag e capacit y o f abuildin g t o th e are a o f it s sout h glazin g o r vic e versa . Littl e i sknown o f thi s storage-glazin g are a relationship . Howeve r i t i s pos -sibl e t o establis h a reasonabl e valu e b y examinin g Balcomb' s storage -glazin g figur e fo r vertica l mas s wall s fro m sectio n 3.2.3.1 . Thi sstorag e quantit y wa s expecte d t o underg o doubl e th e temperatur e excur -sio n o f th e heate d spac e o r abou t 11°C . The n fo r a direc t gai nbuildin g wher e storag e i s isotherma l wit h th e heate d space , a t leas tdoubl e th e mas s mus t b e provide d pe r uni t are a glazin g i n orde r t ostor e th e sam e quantit y o f hea t i n hal f th e temperatur e range . Thi ssuggest s a minimu m therma l storag e valu e o f 122 5 kJ/° C m2 sout hglazin g are a (6 0 BTU/° F FT 2 sout h glazing) . Thi s translate s int oth e followin g equivalence s o f common interio r finis h materials :

Materia l Quantit y pe r m2 sout h glas s

2 mm drywal l 10 0 m2

2 x 1 5 mm drywal l 4 0 m2

quarr y til e 3 0 m2

bric k x 6 4 mm 1 2 m2

wood x 2 5 mm 4 0 m2

I f n o attemp t i s mad e t o deliberatel y increas e th e interna l hea t stor -age o f a buildin g the n th e sout h facin g windo w are a o f th e buildin gwil l b e limite d b y th e therma l storag e containe d i n al l th e material sconventionall y use d i n th e finish , fixtures , an d furnishing s o f th ebuildin g interior . A n importan t an d influentia l stud y b y Shic k an dJone s (65 ) establishe d tha t sout h facin g glazin g shoul d b e limite d t o8 t o 10 % o f th e floo r are a o f a wel l insulated , bu t otherwis e conven -tionall y finishe d woo d fram e buildin g i n orde r t o maintai n indoo r temp -erature s withi n 2 0 t o 26° C an d avoi d wastefu l overheatin g o n clea rwinte r day s a t Madison , Wisconsi n (45°N) . Th e stud y analyse d a hous ehavin g interio r therma l mas s o f 690 0 BTU/° F an d 12 2 ft 2 o f sout hglas s area . Thes e dat a ten d t o corroborat e th e storage-glazin g are arati o presente d above .

5.2.2 . EFFECTIV E THERMAL MASSCompoundin g th e proble m o f determinin g th e quantit y o f therma l storag erequire d b y a give n windo w are a i s th e questio n o f ho w muc h i s effec -tiv e unde r actua l dynami c operation ? Th e simpl e provisio n o f mas swithi n a buildin g doe s no t ensur e tha t i t i s uniforml y o r effectivel yutilize d a s hea t storage .

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The effectivenes s o f therma l storag e i n direc t gai n building s varie swit h th e typ e o f materials , thei r distribution , locatio n an d colour .

I t i s a s importan t t o b e abl e t o mov e hea t int o storag e a t th e rat e o fsola r gain , a s i t i s t o provid e th e capacit y t o absor b al l th e ne tsola r gain . Finis h material s wit h hig h therma l conductivitie s ar epreferre d i n orde r t o facilitat e mos t rapi d hea t transfer . The n a s afloo r covering , quarr y til e i s preferre d t o wood , whic h i s itsel fpreferre d t o carpet , whe n the y al l represen t th e sam e therma l capacity .

Mazri a (66 ) ha s demonstrate d tha t thi n (10 0 mm) larg e are a arrangement sof mas s ar e fa r superio r t o thic k compac t arrangement s o f th e sam e mas si n absorbin g sola r hea t gain s an d thu s controllin g temperatur e excur -sion s i n direc t gai n passiv e sola r buildings . Dea n (67 ) ha s conclude dtha t increase s i n th e thicknes s o f storag e mas s beyon d 3 8 mm ar e no teffectiv e a t increasin g diurna l hea t storag e i n material s locate d o nth e insid e o f th e buildin g envelo p an d a s slab s o n grade .

A mor e detaile d analysi s b y Leben s (68 ) indicate s tha t th e 'turnin gpoint ' thicknes s o f therma l mas s heate d onl y b y reflecte d sola r radia -tio n an d conductio n fro m adjacen t ai r i s 50-9 0 mm, beyon d whic h ther ei s n o furthe r reductio n i n dail y roo m ai r temperatur e fluctuatio n i n adirec t gai n passiv e sola r building .

Dark-coloure d material s directl y expose d t o sola r radiatio n ar e tw o t ofou r time s a s effectiv e a t storin g hea t pe r uni t volum e a s th e sam emateria l heate d onl y b y convecte d ai r (69) . Leben s indicate s tha t th eturnin g poin t thicknes s o f suc h directl y expose d therma l mas s i n floo rslab s i s 15 0 t o 22 5 mm. Consequently , floo r areas , chimneys , an d pila -ster s betwee n window s whic h receiv e direc t sola r radiatio n ar e commonlocation s o f mas s material s fo r hea t storage . However , i t i s no tnecessar y t o attemp t t o immediatel y absor b al l transmitte d sola r energ ywithi n suc h strategicall y locate d an d dark-coloure d materials . Radia -tio n no t absorbe d upo n initia l contac t wit h a surfac e withi n a buildin gi s diffusel y reflecte d t o al l adjacen t surfaces . Thi s reflectio n pro -ces s wil l re-occu r unti l al l th e radiatio n i s absorbe d an d t o a lesse rdegre e re-transmitte d throug h th e windows , ou t o f th e building . Th elighte r th e colou r o f th e surface s withi n th e buildin g the n th e greate rth e numbe r o f re-reflection s an d th e mor e unifor m th e distributio n o fth e sola r radiatio n an d hence , temperature s withi n th e interio r o f th ebuilding . A s lon g a s th e glazin g are a represent s a relativel y smal lproportio n o f th e interio r surfac e are a o f a building , a s i s th e cas ewit h mos t direc t gai n passiv e sola r systems , sola r re-transmissio n i slo w an d consequentl y ver y hig h overal l sola r absorptance s may b eachieved , despit e ligh t coloure d interiors .

Then als o t o b e considere d a s hea t storag e ar e th e surface s o f al l par -titions , ceiling s an d othe r interio r walls . Togethe r the y generall yrepresen t a n are a fou r time s greate r tha n th e floo r are a o f a resi -dence . A doubl e laye r o f drywal l upo n thes e surface s ca n alon e accoun tfo r th e require d hea t storag e o f a windo w are a equa l t o 10 % o f th efloo r are a o f a building .

5.2.3 . THERMAL STANDARDSThe therma l energ y conservatio n standard s o f th e buildin g enclosur eenvelop e hav e a profoun d impac t upo n th e performanc e o f a passiv e sola rheate d building . On th e on e han d th e gros s passiv e sola r gai n throug hglazin g (QS ) i s a functio n o f th e (south ) windo w are a o f a building .On th e othe r han d th e gros s hea t loa d (QL ) i s a functio n o f th e entir ebuildin g envelop e resistanc e t o hea t flo w vi a bot h conductio n an d ai rinfiltration/exfiltration . The n th e percentag e contributio n o f passiv esola r gain s t o th e hea t loa d (QS/QL ) i s increase d no t onl y b y increas -in g th e sout h windo w are a bu t als o b y decreasin g th e buildin g hea tload .

Whil e th e modellin g o f thi s relationshi p i s no t strictl y linear , halv -in g th e hea t loa d o f a buildin g throug h increase d therma l standard scoul d a s muc h a s doubl e th e percentag e contributio n o f passiv e sola rgain s withou t an y chang e i n windo w area . Clearl y a give n quantit y o fpassiv e sola r gai n assume s fa r mor e significanc e whe n applie d t o abuildin g o f lowe r hea t load . I n fac t i t i s onl y whe n hig h therma lstandard s ar e applie d t o th e enclosur e envelop e o f a buildin g tha t it stherma l performanc e become s highl y sensitize d t o variation s i n th eare a an d distributio n o f windows .

The storag e t o glazin g are a ratio , discusse d i n sectio n 5.2. 1 i s als osubjec t t o var y wit h change s i n th e overal l therma l conductanc e o f th ebuildin g a s thi s wil l chang e th e magnitud e o f th e maximu m dail y ne tglazin g gai n whic h mus t b e store d withi n th e interna l fabri c o f th ebuilding . Fo r a buildin g wit h a fixe d sout h windo w area , a lowe r hea tlos s rat e throug h highe r therma l standard s wil l increas e th e maximu mdail y ne t sola r gai n (tha t i s th e differenc e betwee n th e maximu m dail ysola r gai n an d al l th e component s o f buildin g hea t los s durin gdaylight ) an d increas e th e require d storag e mas s i n orde r t o preven toverheating . Alternativel y fo r a buildin g o f fixe d interna l mas sstorage , a lowe r hea t los s rat e throug h highe r therma l standard s wil ldecreas e th e maximu m allowabl e sout h windo w are a i n orde r t o preven toverheating . Th e modellin g o f th e storage/glazin g rati o wit h respec tt o overal l buildin g conductanc e i s no t ye t clearl y established .

I n orde r t o maximiz e th e percentag e passiv e sola r contributio n whil eat th e sam e tim e minimizin g th e are a an d henc e cos t o f passiv e sola rcollector/window s i t i s importan t i n th e desig n o f a passiv e sola rheate d buildin g t o determin e th e maximu m economicall y justifie d therma lstandard s o f th e enclosur e envelope .

The determinatio n o f therma l energ y conservatio n standard s fo r th ebuildin g enclosur e envelop e i s base d upo n lif e cycl e cos t analysi s(70 , 71) . Tha t is , ove r a give n tim e perio d th e presen t wort h o fenerg y cos t saving s du e t o increase d therma l standard s mus t a t leas tequa l th e incrementa l initia l installe d cos t o f th e increase d therma lstandards . Th e proble m i n applyin g thes e lif e cycl e benefit/cos ttechnique s lie s i n establishin g th e perio d o f financia l analysis , th erea l energ y pric e escalatio n rat e an d th e rea l financia l discoun t rat eapplie d t o futur e cas h flow s - al l o f whic h determin e th e presen twort h o f futur e energ y saving s an d i n tur n th e maximu m incrementa l

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economi c investmen t i n increase d therma l standards . Dependen t upo nth e value s chose n fo r thes e parameter s a broa d rang e o f therma lstandard s ca n b e justified , rangin g fro m smal l t o ver y substantia lincrease s abov e contemporar y practices .

Whil e som e builder s hav e introduce d mor e energ y efficien t homes , th emajorit y o f th e buildin g industr y ha s no t bee n innovativ e i n adoptin gincrease d therma l standards , le t alon e th e passiv e us e o f sola renergy . Reflectin g a sale s mentalit y tha t value s lowe r initia l cost sove r lowe r lif e cycl e costs , th e buildin g industr y believe s tha t an yincreas e i n therma l standard s shoul d b e base d upo n a shor t ter mpaybac k perio d - fa r shorte r tha n th e tru e o r eve n mortgag e lif e o f abuilding . Whil e th e publi c secto r ha s move d t o increas e th e minimu mtherma l standard s require d fo r ne w residentia l construction , th e pro -pose d standard s (72) , adapte d fro m ASHRAE 90-7 5 apparentl y embod y th esame shor t paybac k analysis . Thi s conservatis m i s born e o f som epractica l considerations .

The suppl y o f insulativ e an d certai n framin g material s may b e fa routstrippe d b y deman d i f therma l standard s wer e t o b e dramaticall yincreased . Thi s woul d resul t i n counter-productiv e pric e increases .

Conventiona l woo d fram e wal l constructio n ha s a capacit y fo r resistanc einsulatio n whic h i s limite d t o 8 9 mm. Greate r insulatio n thicknes s i nwall s involve s th e us e o f mor e costl y rigi d insulatio n a s sheathin g o rmore costl y framin g practice s suc h a s usin g deepe r studs , strappin gove r studs , staggere d stu d wall s o r doubl e wal l construction . A s ye tther e i s littl e empiricall y derive d dat a o n th e cos t o f thes e struc -tura l modification s no r o f fittin g window s an d door s t o thicke r walls .

Finally , ther e ha s bee n enormou s inflatio n i n th e pric e o f housin gunti l th e curren t economi c recessio n whic h ha s brough t abou t a down -tur n i n bot h housin g start s an d sales . Thes e circumstance s creat e apowerfu l disincentiv e t o an y increas e i n th e initia l cos t o f housing .

However usin g longe r paybac k period s i t ha s bee n demonstrate d tha thighe r level s o f therma l energ y conservatio n standard s ar e economicall ycommensurat e wit h th e rigour s o f th e Canadia n climat e (73,74,75,76) ,(se e als o reference s 53,63,65) . I t i s necessar y tha t th e publi csecto r no t onl y provid e interi m minimu m therma l standard s fo r build -ings , bu t als o specif y an d standardiz e lif e cycl e periods , rea l pric eescalatio n factor s o f conventiona l energie s an d th e rea l discoun t rat eof futur e cas h flow s i n orde r t o minimiz e confusio n an d bia s i n th efinancia l analysi s o f therma l energ y conservatio n standard s an d sola rheatin g systems . Additionally , whil e maximu m infiltratio n rate s ar eset t o contro l leakag e abou t windo w sashe s an d doo r frames , th e big -ges t singl e 'loophole ' i n existin g energ y conservatio n standard s i s th elac k o f an y meaningfu l standar d t o ensur e a minimu m resistanc e t o ai rinfiltratio n withi n a building , a s built , a s a whole . I t i s recom -mended tha t a standar d b e se t t o tes t al l ne w building s b y ai rpressurizatio n o r trace r ga s techniques .

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Hig h therma l standard s i n th e buildin g enclosur e envelop e ar e neve r a sinexpensiv e a s whe n the y ar e designe d an d buil t int o a dwellin g uni tfro m th e beginning .

5.2.4 . MATHEMATICAL MODELLINGWhil e method s ar e unde r developmen t b y many researcher s a s ye t n o stan -dar d model , corroborate d b y actua l monitore d dat a an d approve d b y bot hpubli c an d privat e interes t groups , exist s fo r calculatin g an d predic -tin g th e passiv e sola r heate d componen t o f a building . Unti l th e nec -essar y passiv e sola r performanc e tool s ar e develope d an d disseminated ,th e industry-wid e recognitio n an d applicatio n o f passiv e sola r heatin gwil l b e seriousl y impaired .

To dat e th e heatin g loa d upo n a buildin g ha s bee n determine d a s asimpl e functio n o f th e building' s overal l hea t conductanc e rat e pe rdegree-tim e (calculate d a s describe d i n 77 ) an d th e indoor-outdoo rtemperatur e differenc e ove r th e correspondin g tim e period . Th e heat -in g degree-day s use d i n th e calculatio n o f annua l heatin g load s ar esimpl y th e year-lon g su m o f dail y mea n indoor-outdoo r temperatur edifference s an d hav e bee n compile d fo r many locations .

I t shoul d b e clearl y understoo d tha t thi s metho d estimate s th e ne theatin g loa d upo n a buildin g whic h mus t b e supplie d b y th e activ eheatin g system . Th e remainde r o f th e building' s gros s hea t los s i ssupplie d o r 'balanced ' b y passiv e sola r an d interna l hea t gain s whic har e indirectl y accounte d i n th e compilatio n o f degre e day s b y th e us eof a n artificiall y lo w indoo r temperatur e o f 18° C whe n i n fact , th eindoo r desig n temperatur e i s 22°C .

When building s wer e poorl y insulate d an d no t specificall y optimize d fo rpassiv e sola r performance , th e passiv e sola r an d interna l gain s withi na buildin g generall y represente d suc h a smal l percentag e contributio nt o th e gros s annua l hea t loa d tha t th e degree-da y metho d coul d b e use dt o predic t th e ne t hea t loa d upo n a buildin g wit h acceptabl e accuracy .However wit h increasin g insulatio n level s an d mor e air-tigh t construc -tio n th e relativ e magnitud e o f passiv e sola r an d interna l hea t gain swit h respec t t o gros s hea t load s hav e rise n unti l toda y th e conven -tiona l degree-da y metho d ove r estimate s annua l ne t heatin g load s b y a naverag e o f 25 % (78,79 ) an d wil l becom e eve r les s accurat e a s th etherma l standard s o f building s ar e furthe r increased . Whil e i t i spossibl e t o adjus t th e balanc e heatin g temperatur e downwar d (a s i nreferenc e 78 ) t o increas e th e accurac y o f th e degree-da y method , i twoul d stil l exhibi t n o sensitivit y t o variation s i n passiv e sola rgain s du e t o change s i n windo w are a an d orientation , no r woul d i tdirectl y identif y th e passiv e sola r an d interna l gai n component s o f abuilding , bot h o f whic h mus t b e clearl y visibl e i n attemptin g t ooptimiz e th e passiv e sola r performanc e o f an y buildin g durin g design .

The degree-da y metho d als o ha s sever e limitation s i n th e determinatio nof certai n component s o f th e overal l buildin g hea t loa d whic h ar e no tsimple , linea r function s o f indoor-outdoo r ai r temperatur e differences ,nor stead y stat e hea t flow . Thes e includ e hea t losse s belo w grade ;

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ai r infiltration/exfiltration ; th e annua l insulatin g effect s o f therma lshutters ; an d th e transien t insulatin g effect s o f exterio r mass /masonar y material s (80) .

I n orde r t o develo p a mor e realisti c understandin g o f th e therma l per -formanc e o f a buildin g whil e avoidin g th e tim e an d expens e o f monitor -in g larg e number s o f building s th e digita l compute r i s use d t o simulat eth e dynami c therma l load s an d passiv e sola r gain s o f a building . B yprocessin g hourl y recording s o f actua l meteorologica l data , typicall yconsistin g o f outdoo r dr y bul b temperature , windspeed , an d horizonta lsola r radiation , th e compute r ca n rapidl y calculat e th e man y component sof buildin g hea t load , passiv e sola r gain s an d interna l hea t gain s fo reach hou r ove r 876 0 hour s i n a year . Dynami c compute r simulatio n i spotentiall y th e mos t sophisticate d metho d o f modellin g th e performanc eof a passiv e sola r heate d buildin g a s bot h th e extrem e an d transien teffect s o f outdoo r weathe r an d buildin g occupanc y may b e analyzed .

Many softwar e package s hav e bee n develope d whic h mode l th e performanc eof activ e sola r heatin g system s (81,82) . Whil e i t i s necessar y tha tthes e program s accuratel y simulat e a building' s therma l loads , the y d onot directl y accoun t fo r indirec t no r eve n direc t passiv e sola r hea tgains . Furthermor e th e representatio n o f th e buildin g loa d itsel f i soversimplified . Agai n th e buildin g loa d i s calculate d a s a linea rfunctio n o f th e overal l buildin g hea t conductanc e rat e an d th e indoor -outdoo r temperatur e difference , thoug h o n a n hourl y basis . Sinc e th eindoo r temperatur e i s se t artificiall y lo w an d becaus e al l th e compon -ent s o f th e buildin g hea t loa d ar e lumpe d int o on e constant , then ,despit e hourl y simulatio n th e buildin g loa d calculatio n suffer s fro mal l th e drawback s note d previousl y fo r th e degree-da y method . Addi -tionall y th e metho d incorrectl y predict s th e tim e distributio n o f th eheatin g loa d becaus e i t doe s no t directl y accoun t fo r th e therma lcapacitanc e effect s o f th e building . Thes e includ e th e sol-ai r tem -perature s an d time-la g conductanc e o f th e buildin g envelop e (83 ) an dth e transien t temperatur e fluctuation s withi n th e ai r an d material s o fth e buildin g interio r du e t o passiv e sola r hea t gains , distributio n an dstorage .

Far mor e detaile d an d comprehensiv e buildin g therma l load s an d passiv esola r performanc e simulatio n program s ar e unde r developmen t i n th eUnite d State s (84 ) an d t o a lesse r degre e i n Canad a (85) . Howeve rsome o f thes e program s suc h a s NBSLD (86) , ar e engineering-oriente dprograms . Tha t is , whil e the y may exhaustivel y analyz e therma l load sand direc t passiv e sola r gains , thei r prim e functio n i s t o siz e th educts , pipes , fans , pumps , tanks , chillers , furnace s an d othe r mechan -ica l equipmen t o f a building' s environmenta l contro l systems , afte rth e architectura l desig n an d specification s ar e largel y complete .

The passiv e sola r simulatio n programs , whil e omittin g superfluou sengineerin g detail , var y significantl y i n thei r method s o f modellin gth e performanc e o f passiv e sola r system s an d th e buildin g envelope ;and i n thei r applicabilit y t o th e differen t generi c type s o f passiv esola r heating .

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The proble m wit h al l compute r simulatio n program s i s tha t eac h i s onl yas goo d a s th e progra m itsel f i s mor e or les s o f a mode l o f reality .Whil e Balcom b (87 ) ha s demonstrate d tha t highl y accurat e passiv esimulatio n softwar e ca n b e developed , th e accurac y o f mos t buildin gand passiv e simulatio n program s i s unknown . Fe w simulatio n program shave bee n corroborate d b y actua l monitore d data , an d n o standard sexis t b y whic h t o determin e whethe r th e monitore d dat a itsel f i smeaningfu l (88) . Furthermor e n o standard s exis t b y whic h t o judg e th erelevanc e o f th e content s o f a give n simulatio n progra m fo r aparticula r applicatio n (89) .

However , a s a n instrumen t o f professiona l practice , educatio n an dresearch , th e deman d fo r passiv e sola r an d buildin g performanc e simula -tio n softwar e wil l continu e t o gro w wit h increasin g interes t i n passiv esola r heating , and , a s th e developmen t o f lo w cos t micro-electroni ccomputin g equipmen t facilitate s a fa r mor e sophisticate d an d sensitiv eanalysi s o f th e performanc e o f building s b y a n increasingl y broa d seg -ment o f buildin g designer s an d consultants . Indeed , i n tim e i t wil lbe necessar y t o accuratel y simulat e th e performanc e o f al l ne w build -ing s wheneve r a performanc e rathe r tha n a prescriptiv e energ y conserva -tio n cod e fo r building s come s int o effect . Accordingl y th e furthe rdevelopmen t o f passiv e sola r an d buildin g performanc e simulatio n soft -ware shoul d b e mos t activel y pursued .

Shor t o f developin g standardize d method s an d algorithm s fo r therma lsimulatio n themselves , th e relevan t publi c an d privat e institution sshoul d se t standard s fo r determinin g th e applicabilit y an d fo r testin gth e accurac y o f therma l simulatio n programs . I n orde r t o bes t facili -tat e th e optimizatio n o f th e performanc e o f th e buildin g itself , tw okey goal s shoul d appl y t o th e developmen t o f passiv e sola r an d therma lsimulatio n software . First , i t i s necessar y t o develo p highl y inter -activ e softwar e whic h i s convenien t t o us e during , an d no t afte r th ebuildin g desig n process , whe n i t i s necessar y t o determin e th e relativ eperformanc e o f alternativ e architectura l desig n ideas . Secondly , th esoftwar e shoul d b e sufficientl y flexibl e an d sensitiv e t o respon d t oinnovativ e variation s i n passiv e sola r buildin g design , us e o fmaterial s an d conservatio n methods .

Followin g i s a brie f outlin e o f th e analytica l feature s o f a passiv esola r an d therma l load s simulatio n program .

I t i s necessar y t o directl y calculat e bot h passiv e sola r an d interna lheat gain s withi n th e building . Thi s implie s tha t th e indoo r temper -atur e wil l no t b e se t arbitraril y low , bu t wil l assum e rea l value swhic h wil l fluctuat e wit h th e quantit y o f hea t withi n th e building .Thi s i n turn , implie s th e calculatio n o f gros s rathe r tha n ne t energ yflo w acros s th e buildin g envelope . Th e calculatio n o f rea l indoo rtemperature s als o facilitate s th e simulatio n o f activ e hea t suppl y an dheat remova l apparatus . Howeve r i t i s essentia l tha t thes e apparatu sbe inoperativ e ove r a sufficien t temperatur e rang e t o allo w fo rpassiv e hea t exchanges . Th e maintenanc e o f th e buildin g interio r a t aspecifi c temperatur e ca n arbitraril y eliminat e th e effect s o f passiv esola r hea t gai n an d storage .

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Each componen t o f th e hea t flo w acros s th e buildin g shoul d b e modelle dindependentl y wher e factor s othe r tha n indoor-outdoo r ai r temperatur edifference s ar e involved . A s a minimum , fou r distinc t component sshoul d b e identified . Hea t flo w acros s opaqu e component s abov e grad eshoul d accoun t fo r sol-ai r temperature s an d time-la g conductance .Heat flo w acros s component s belo w grad e shoul d accoun t fo r th e modera -tio n an d time-la g o f groun d temperature s whic h increas e wit h dept hbelo w grade . Hea t flo w acros s window s i s mor e closel y a functio n o findoor-outdoo r ai r temperatur e difference s bu t shoul d allo w fo r th eactio n o f therma l shutters . Finall y hea t flo w du e t o ai r infiltration /exfiltratio n shoul d accoun t fo r leakag e throug h bot h crack s an d pore si n th e buildin g envelope ; bot h win d an d stack-effec t ai r pressur edifferences ; an d th e effect s o f landscapin g an d buildin g heigh t upo nwin d an d stac k pressures .

As a n absolut e minimu m i t i s necessar y tha t th e progra m b e abl e t ocalculat e passiv e sola r hea t gain s throug h glazin g an d th e subsequen tabsorptio n an d distributio n o f th e sola r gai n withi n th e buildin ginterior , accountin g fo r alternativ e storag e materia l an d locatio nstrategies , possibl e multi-zon e interiors , an d activ e convectiv eequipment . Fo r furthe r passiv e flexibility , i t i s desirabl e tha t th eprogra m als o b e abl e t o simulat e othe r type s o f passiv e sola r heating ,particularl y sunspac e an d vertica l mas s gai n systems .

The simulatio n o f passiv e sola r system s an d sol-ai r temperature srequire s th e calculatio n o f sola r intensit y upo n non-horizonta lsurfaces . Method s whic h determin e sola r intensitie s fro m table s o fclea r da y sola r intensit y publishe d b y ASHRAE, usin g percentag esunshin e hour s o r clou d cove r factor s ar e inadequat e a s th e trans -missio n an d dispersio n o f sola r radiatio n b y th e atmospher e ar e no twel l represente d b y thes e factors .

Rathe r i t i s desirabl e t o wor k fro m actua l recording s o f sola rradiatio n whic h ar e take n hourl y upo n a horizonta l surfac e a t 5 6location s i n Canada . Thes e recording s consis t o f tw o components : abeam componen t whic h arrive s directl y fro m th e sun ; an d a diffus ecomponent whic h ha s bee n scattere d b y element s o f th e atmospher e an di s generall y assume d t o b e isotropic , o r uniform , fro m al l part s o fth e sky . When isolated , th e bea m intensit y upo n an y non-horizonta lsurfac e i s calculate d b y complex , bu t straightforwar d trigonometri crelationship s whic h determin e th e angl e o f incidenc e betwee n th e su nand th e surfac e norma l a t a give n date , tim e an d latitude . Diffus esola r radiatio n fro m bot h th e sk y an d fro m groun d reflectio n ar e cal -culate d a s simpl e function s o f th e surface' s slop e towar d th e sk y an dgroun d respectively .

Sinc e onl y 4 o f 5 6 Canadia n radiatio n station s recor d diffus e sola rradiation , th e proble m i n sola r calculation s lie s i n accuratel y differ -entiatin g th e tota l horizonta l radiatio n readin g int o it s tw o basi cpart s prio r t o trigonometri c translation . Li u an d Jorda n firs t pre -sente d a metho d o f determinin g th e isotropi c diffus e componen t o f hori -zonta l radiatio n a s a functio n o f th e proportio n o f tota l recorde dhorizonta l radiatio n t o th e calculate d horizonta l extra-terrestria l

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sola r intensit y abov e th e earth' s atmospher e (90) . A numbe r o fCanadian s (91,92 ) hav e develope d simila r sola r transmittanc e an d dis -persio n relationship s fro m Canadia n dat a an d hav e foun d highe r diffus ecomponent s tha n predicte d b y th e Liu-Jorda n algorithm . Howeve r th ewhol e proble m i s compounde d b y th e fac t tha t neithe r th e sk y no rgroun d reflecte d diffus e component s ar e evenl y distribute d (93 ) bu tar e genera l o r centere d abou t th e directio n o f th e sun . Accordingl ysome o f th e horizonta l diffus e radiatio n predicte d b y th e abov emethod s may b e treate d a s bea m radiatio n (94) .

Alternativel y Ha y ha s develope d mor e comple x method s whic h compensat efo r diffus e augmentatio n du e t o multipl e reflectio n betwee n th e groun dand clou d cove r (95 ) an d whic h calculat e th e diffus e radiatio n fro mth e sky , allowin g fo r varyin g degree s o f diffus e anisotrop y (96) .Whil e Hay' s studie s o f availabl e sola r radiatio n ar e clearl y th e mos texhaustiv e whic h hav e bee n undertake n i n Canad a t o date , the y improv eth e accurac y o f calculate d value s o f inciden t sola r radiatio n b y onl yone o r tw o percentag e point s beyon d th e forementione d technique s ye tinvolv e a considerabl e increas e i n mathematica l complexity . Furthe rth e metho d fail s t o defin e th e angula r dispersio n o f thi s anisotropi cdiffus e radiation . Consequentl y i t i s difficul t t o determin e th e sub -sequen t transmissio n o f thi s radiatio n throug h glazin g materials .Unti l th e non-horizonta l inciden t an d transmitte d sola r intensitie scalculate d b y thes e sola r distributio n relationship s receiv e greate rempirica l corroboration , i t i s difficul t t o us e an y o f the m wit h grea tconfidence .

Sinc e th e calculatio n o f non-horizonta l sola r intensitie s involve ssolvin g th e tim e dependen t angula r relationshi p betwee n th e receivin gsurfac e an d th e sun , i t i s possibl e t o simultaneousl y determin e th eeffect s o f overhea d shadin g devices , an d specula r reflector s whic h ar efrequentl y use d t o enhanc e th e seasona l performanc e o f passiv e sola rsystems . I t i s als o desirabl e t o determin e th e shadin g effect s fro mlatera l projection s o f th e sam e buildin g o r fro m othe r object s an dbuildings .

Whil e dynami c compute r simulatio n o f passiv e sola r heate d building smay b e th e mos t accurat e an d flexibl e performanc e modellin g tool , i tmay b e possibl e t o develo p simple r non-dynami c passiv e sola r perfor -mance algorithm s fro m extensiv e sensitivit y analysi s o f repeate dcompute r simulations . Whil e som e flexibilit y an d accurac y may b elost , simple r lon g han d o r programmabl e calculator-typ e passiv e per -formanc e method s woul d b e comprehensibl e an d availabl e t o a broade rsegment o f people . Balcom b (a s i n referenc e 29 ) ha s demonstrate d tha tth e hourl y therma l networ k analysi s o f building s wit h passiv e vertica lmass wall s ca n b e reduce d t o a consisten t functio n o f a building' smonthl y solar/loa d ratio . Whil e thi s techniqu e i s applie d t o bot hdirec t an d indirec t passiv e sola r system s i n a n ongoin g Passiv e

Residentia l Desig n Competitio n (97 ) i n th e Unite d States , i t i s use donl y i n th e absenc e o f a simplifie d procedur e fo r calculatin g th eperformanc e o f direc t gai n passiv e sola r systems . Nevertheles s i t i sindicativ e o f th e typ e o f non-dynami c performanc e evaluatio n metho dwhic h coul d b e devise d fo r direc t passiv e sola r heate d buildings .

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These simplifie d method s ar e a s importan t t o th e widesprea d desig n o fpassiv e system s a s wa s th e developmen t o f th e 'f ' char t metho d fo ractiv e sola r heatin g system s (98) .

The Ne t Annua l Hea t Los s Facto r Metho d presente d b y Mitala s wa sdevelope d fro m extensiv e compute r simulatio n o f residentia l building si n th e Canadia n climate . Whil e i t i s certainl y a n improvemen t ove rth e degree-da y metho d fo r predictin g ne t heatin g loads , a s i t provide snet hea t los s figure s fo r window s an d wall s i n variou s orientations ,th e Ne t Annua l Hea t Los s Facto r Metho d i s no t adequat e a s a simplifie dpassiv e sola r performanc e evaluatio n tool . I t doe s no t directl yidentif y passiv e sola r gain s throug h glazin g no r interna l hea t gain sdue t o occupancy . Furthermor e i t make s n o accoun t o f th e effec t o fth e building' s therma l capacitanc e no r over-al l conductanc e upo n th eutilit y o f th e passiv e sola r gain .

Any kin d o f passiv e sola r performanc e evaluatio n method , regardles s o fwhethe r i t b e highl y interactive , dynami c compute r simulatio n o r a mor esimplifie d tabl e an d char t method , assume s tha t th e buildin g for m an dconstructio n ar e sufficientl y resolve d t o appl y numerica l analysis . Bu tneithe r o f thes e performanc e evaluatio n method s ar e usefu l durin g th econcep t o r schemati c desig n phas e wher e th e buildin g for m an d con -structio n detail s ar e no t resolved . Ye t mos t o f th e basi c desig n deci -sion s includin g image , siting , orientation , overal l form , interio r lay -out , windo w locations , etc. , whic h affec t passiv e sola r performance ,ar e made a t thi s time . I f passiv e sola r performanc e i s t o hav e an yimpac t durin g thi s critical , embryoni c perio d o f design , i t i s impor -tan t t o develo p a thir d leve l o f non-analytical , passiv e concep tdesig n tools . Thes e ar e commonl y calle d rules-of-thum b an d identif yth e pattern s betwee n buildin g element s whic h result s i n effectiv e pas -siv e sola r performanc e (e.g . n o additiona l storag e i s require d whe nth e sout h facin g windo w are a i s les s tha n 10 % o f th e floo r area) . Th eapparen t simplicit y o f passiv e sola r rules-of-thum b i s misleadin g a sthe y ar e gleane d fro m thorough-goin g performanc e simulatio n an d moni -torin g o f passiv e sola r heate d building s (99) , b y whic h i t i s possibl et o identif y an d prioritiz e th e relativ e meri t o f energ y conservin gdesig n strategies .

The developmen t o f goo d rules-of-thum b fo r passiv e sola r desig n doe snot forg o th e nee d fo r mor e detaile d performanc e evaluatio n tools .Rathe r the y ar e use d t o guid e th e conceptua l developmen t o f a buildin gdesig n o r desig n alternative s throug h t o a mor e explici t stat e where -afte r detaile d performanc e evaluatio n technique s may b e used . Suc hrule-of-thum b guide s t o decisio n makin g ar e importan t no t onl y t o th edesigne r an d (owner ) builder , bu t ar e als o meaningfu l t o th e discrimin -atin g purchase r o f a ne w home .

5.2.5 . TECHNICAL ANALYSI STher e i s a glarin g lac k o f dat a concernin g th e performanc e o f passiv esola r building s i n th e Canadia n climate . Ye t i t i s precisel y thi styp e o f hard , objectiv e informatio n whic h i s require d i n orde r t ojudg e th e relativ e meri t o f passiv e sola r heating . Notwithstandin g

th e absenc e o f standardize d therma l simulatio n softwar e i t i s never -theles s possibl e t o evaluat e th e therma l performanc e o f som e passiv esola r heate d building s b y a variet y o f techniques .

I n orde r t o pu t a handl e upo n th e potentia l o f passiv e sola r heatin gi n Canada , suc h a n evaluatio n wa s undertake n t o determin e th e perfor -mance o f a direc t glazin g gai n typ e passiv e sola r heate d buildin gwhose glazin g are a an d therma l standard s wer e allowe d t o vary . Afurthe r descriptio n o f th e analytica l procedure s an d result s o f thi sstud y ar e containe d i n Appendi x C .

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6. MATERIAL AND COMPONENT DEVELOPMENTPerhap s th e mos t significan t forc e behin d th e developmen t o f activ esola r heatin g system s i s tha t th e concep t identifie s nove l an d dis -cret e component s fo r manufacture , presentin g a prospec t fo r industria land entrepreneuria l opportunit y whic h i s a t leas t a s importan t t o thei rpromotio n a s i s energ y displacemen t itself . B y contras t passiv e sola rheatin g i s see n largel y a s a n architectura l desig n proble m rathe r tha na proble m o f industrialize d produc t developmen t an d acceptance . Conse -quentl y an d contributin g i n par t t o a lo w leve l o f awarenes s o f passiv esystems , ther e ar e fe w commercia l proponent s o f passiv e sola r products .

Passiv e sola r heatin g doe s requir e soun d architectura l desig n suc htha t al l th e part s o f a buildin g serv e als o a s a thermodynami c syste mt o entra p radian t energy . Throug h th e re-orderin g o f th e component snormall y use d i n a building , particularl y th e siz e an d locatio n o fglaze d areas , goo d passiv e sola r peformanc e ca n alread y b e realized .However , beyon d th e facilitatio n o f passiv e sola r gain s throug h thes earchitectura l techniques , furthe r improvement s i n th e efficienc y o fpassiv e sola r utilizatio n i s a t leas t a s muc h a proble m o f developin gmaterial s an d component s whos e thermodynami c propertie s ar e bette roptimize d fo r passiv e sola r performance . Thi s create s thre e prim edirective s fo r th e developmen t o f passiv e sola r buildin g products :

1) maximiz e sola r transmissivity ;

2) maximiz e resistanc e t o hea t loss ; an d

3) maximiz e hea t storag e capacit y withi n th e building .

6. 1 TRANSPARENT INSULATION .Taken togethe r th e firs t tw o directive s defin e th e nee d fo r a produc ttha t b y increasin g th e ne t sola r gai n o f glazin g system s woul d benefi tal l type s o f sola r heatin g regardles s o f whethe r activ e o r passive .Thi s typ e o f materia l i s terme d transparen t insulation . A s ye t n o off -the-shel f glazin g syste m i s sufficientl y optimize d t o b e terme d a tru etransparen t insulator . Fo r exampl e commonl y availabl e 'clear ' doubl eglazin g consist s o f tw o light s o f 5 mm glas s enclosin g a 1 2 mm air -space . I t transmit s 65 % o f th e tota l inciden t sola r radiatio n an d ha sa therma l resistanc e o f 0.3 2 m2°C/W. B y contras t th e minimu m therma lresistanc e allowe d i n wall s unde r th e ne w energ y conservatio n cod e (72 )i s te n time s thi s value . Whil e th e therma l resistanc e o f transparen tmaterial s may neve r excee d thos e o f opaqu e wal l assemblies , ther e i sconsiderabl e an d eve n dramati c potentia l t o increas e th e therma lresistanc e o f glazin g assemblies .

I n orde r t o increas e th e therma l resistanc e o f glazin g system s i t i snecessar y t o suppres s hea t transpor t acros s th e glazin g vi a conduction ,convectio n an d long-wav e infr a re d radiation . Conductio n i s suppresse dby ai r entrape d betwee n th e glazin g lights . I n doubl e glaze d system sresistanc e t o hea t flo w increase s wit h th e thicknes s o f th e airspac eunti l a spacin g o f 1 2 mm i s reached . Thereafte r increase d convectiv etransfe r largel y counteract s an y furthe r increase s i n resistanc e

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despit e thicke r airspaces . Th e onl y effectiv e strateg y t o suppres sconvectiv e transfe r i n glazin g system s i s t o compartmentaliz e th e air -spac e int o an y numbe r o f layer s eithe r paralle l o r perpendicula r t oth e oute r glazin g lights .

Whil e paralle l separatio n maintain s undistorte d visua l transparency ,cost s ris e disproportionatel y t o therma l resistanc e beyon d tripl eglazing . Significantl y th e extr a glazin g light(s ) als o decreas e sola rtransmission . Howeve r eve n th e therma l resistanc e o f tripl e glazin gcan b e improved . I t i s no t widel y appreciate d tha t th e temperatur edifferentia l acros s eac h airspac e i n tripl e glazin g i s abou t on e hal ftha t withi n a doubl e glaze d unit . Sinc e temperatur e differential sdriv e convectiv e forces , the n a wide r airspac e i s tolerabl e withi ntripl e glazin g befor e convectiv e transfe r disrupt s furthe r increase si n therma l resistance . Th e turnin g poin t thicknes s o f a n airspac e i ntripl e glazin g i s close r t o 1 9 mm a s compare d t o 1 2 mm fo r doubl eglazin g (100) . Thi s phenomeno n i s no t embodie d i n tripl e glazin gsystem s currentl y bein g retaile d i n Canad a whic h hav e a maximu mspacin g o f 1 2 mm an d therma l resistanc e o f . 5 t o .5 5 m2°C/W. Whil eth e therma l resistanc e o f thes e unit s compare s favourabl y t o doubl eglazin g i t may b e increase d anothe r 25 % t o 0.6 5 m2°C/ W b yincorporatin g 1 9 mm airspaces .

Compartmentalizatio n o f th e airspac e perpendicula r o r norma l t o th eoute r glazin g light s i s accomplishe d b y a variet y o f 'honeycombing 'techniques . Thi n plasti c membrane s shape d a s squar e o r hexagona lhoneycombs , o r a s 'v ' corrugations , hav e bee n explore d (101 ) an d a nopen-ende d honeycom b syste m i s unde r productio n i n Canad a (102) . Th epotentia l performanc e o f glazin g wit h honeycom b convectiv e suppressor si s considerabl e a s th e sola r transmissio n remain s hig h whil e th e air -spac e thicknes s i s increase d withou t convectiv e disruption . Whil edefinitiv e tes t result s ar e no t ye t available , th e ope n honeycom bsyste m (a s i n referenc e 102 ) may hav e a n overal l therma l resistanc e o f1.4 1 t o 1.7 7 m2°C/W. Sinc e thes e honeycom b glazing s distor t visua lacuit y throug h th e glazing , the y hav e bee n applie d onl y t o fla t plat esola r collectors . Howeve r thei r attribute s a s transparen t insulator sensur e thei r feasibilit y fo r passiv e sola r heatin g particularl y i nclerestor y windows , greenhouses , mas s walls , an d thermosipho n system swher e perfec t visua l acuit y i s no t important .

A thir d approac h t o compartmentalizatio n o f th e airspac e i s terme dpolyhedra l glazing . I t i s forme d b y foamin g a transparen t materia lint o cell s 6 t o 1 2 mm i n diamete r whic h ar e the n rolle d o r extrude dint o a laye r 5 0 mm i n thickness . Telke s (103 ) ha s reporte d a sola rtransmissio n i n exces s o f 60 % an d a n overal l therma l resistanc egreate r tha n 0.6 5 m2°C/ W fo r thi s typ e o f material . Whil e trans -lucen t t o ligh t th e polyhedra l cellula r structur e o f th e materia lsuggest s hig h strengt h an d a potentia l fo r self-supporting , long-spa napplications . Whil e polyhedra l glazin g ha s receive d littl e furthe rdevelopmen t o r commercializatio n th e concep t ha s significan t potentia las a transparen t insulator .

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The fina l componen t o f hea t transfe r acros s glazing , long-wav e infr are d re-radiatio n may b e significantl y reduce d b y th e us e o f a 'hea tmirror' . Simila r t o widel y availabl e sola r contro l film s an d reflec -tiv e glazings , hea t mirror s ar e forme d b y depositin g a thi n metalli coxid e coatin g upo n glas s o r plastic . Thes e metalli c coating s ar e o flo w emittanc e t o long-wav e radiatio n an d may b e positione d t o reflec tlon g wav e radiatio n bac k t o th e heate d space . Howeve r unlik e sola rcontro l film s whic h als o reflec t significan t quantitie s o f inciden tsola r radiation , hea t mirror s ar e highl y transparen t t o shortwav e an dvisibl e sola r radiatio n (104,105) . Fo r example , Phillip s hav edevelope d a n indiu m oxid e coatin g wit h a sola r transmissio n o f 85 % an dan emissivit y o f 0.1 0 whic h whe n applie d t o th e inne r surfac e o f th eoute r ligh t i n a doubl e glaze d windo w achieve s a n overal l therma lresistanc e o f 0.7 8 m2°C/W; an d whe n krypto n i s substitute d i n th eairspace , th e syste m ha s a theoretica l resistanc e o f 1. 1 m2°C/ W(106) . A hea t mirro r develope d b y Sunte k Researc h Associate s whic h i sdeposite d upo n plasti c ha s a n emissivit y o f 0.1 5 an d a transmissivit yof 80%. A s a stick-o n fil m thi s hea t mirro r i s highl y feasibl e fo rretrofittin g upo n existin g windows . Also , i n collaboratio n wit h th eSola r Architectur e Grou p a t th e Massachusett s Institut e o f Technolog ya glazin g syste m ha s bee n develope d consistin g o f a double-side dSunte k hea t mirro r betwee n tw o light s o f glas s separate d b y 1 6 mmairspaces . I t ha s a n overal l sola r transmissio n o f 59 % an d a n overal lheat transfe r resistanc e o f 0.8 5 m2°C/W(107) .

I n orde r t o increas e th e transmissivit y o f an y glazin g i t i s necessar yt o decreas e absorptanc e losse s withi n th e glazin g materia l an d reflec -tanc e losse s du e t o refractio n a t th e glazin g surfaces . Thes e ar eaccomplishe d b y reducin g th e thickness , coefficien t o f extinctio n an drefractiv e inde x o f th e glas s respectively . Th e firs t strateg y i smost straightforwar d t o implemen t a s thi n glas s i s available . Howeve rfo r reason s o f strengt h thi s reduce s th e maximu m allowabl e are a o fglazin g unit s whic h increase s th e perimete r t o are a rati o o f th eglazing , causing , i n turn , a theoretica l increas e i n ai r infiltration .Nevertheles s reducin g th e typica l glas s thicknes s fro m 5 t o 3 mm woul dincreas e th e norma l transmittanc e o f doubl e glazin g b y 9.2 % t o 71.1% .

The extinctio n coefficien t o f glas s i s reduce d primaril y b y lowerin gth e iro n oxid e conten t o f glass . Whil e n o Canadia n manufacture r pro -duce s a lo w iro n oxid e conten t glass , th e product s o f a n America n manu -facture r o f lo w iro n oxid e conten t glas s ar e importe d an d distributed .I n clea r finish , a t .05 % iro n oxid e conten t i t i s calle d appropriatel y'Lo-Iron ' shee t glas s (108) . Th e us e o f thi s glas s woul d increas e th etransmissivit y o f 5 mm doubl e glazin g b y 19.5 % t o 77.8% .

Whil e lo w refractiv e inde x film s may b e applie d t o glas s o r leache d in -t o a glas s surfac e b y aci d (a s i n referenc e 58 ) thes e type s o f glas sar e no t readil y availabl e a s th e technique s use d ar e eithe r to o expen -siv e o r d o no t yiel d a weathe r stabl e surface . Howeve r sinc e approxi -matel y 8 % o f th e availabl e sola r radiatio n i s los t t o reflectio nthroug h eac h shee t o f glas s a t norma l incidence , significan t improve -ment s i n th e sola r transmissivit y o f glazin g coul d b e mad e throug h th eapplicatio n o f lo w inde x o f refractio n materials . Fo r exampl e th etransmissivit y o f an y doubl e glazin g increase s 10 % whe n th e refractiv einde x o f th e glazin g materia l i s lowere d fro m 1. 5 t o 1.3 .

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A numbe r o f plasti c material s hav e a n inde x o f refractio n nea r o r lowe rtha n glas s an d hav e significan t potentia l fo r sola r application s a sthe y posses s hig h strengt h an d ar e workabl e an d relativel y inexpensiv e(109) . Howeve r many plasti c glazing s ar e translucent , combustible ,hav e hig h therma l expansio n coefficients , an d ar e subjec t t o ultr a vio -le t solarizatio n an d deterioratin g transmissivities . Throug h furthe rmolecula r engineerin g som e o f th e drawback s o f plasti c glazing s may b eovercome . Sunte k Researc h Associate s hav e develope d a plasti c 'Sola rMembrane' , probabl y simila r t o 'Teflon' , whic h ha s a sola r transmissiv -it y o f 95 % an d a lifetim e o f greate r tha n 3 0 year s an d doe s no t solar -iz e rapidly . When 4 layer s o f th e 'Sola r Membrane ' ar e separate d b y 1 9mm airspace s a transparen t insulatio n i s forme d wit h a transmissivit yof 82 % an d a therma l resistanc e o f 0.8 4 m2°C/ W (110) .

These sola r transmissio n improvemen t strategie s ar e eve n mor e effectiv ewhen applie d t o tripl e glazing . Reducin g th e thicknes s o f tripl eglazin g fro m 5 mm t o 3 mm increase s sola r transmissivit y 14.2 % fro m 5 3t o 60.5% . Th e us e o f lo w iro n oxid e conten t glas s increase s th e trans -missivit y o f 5 mm tripl e glazin g 30.8 % fro m 5 3 t o 69.3% . An d whe n th erefractiv e inde x o f an y tripl e glazin g materia l i s lowere d fro m 1. 5 t o1. 3 th e transmissivit y increase s 15%.

6. 2 MOVABLE INSULATIO NThe mos t familia r produc t whic h ha s bee n associate d wit h passiv e sola rheatin g system s i s th e therma l shutte r o r blind . Unlik e tru e trans -paren t insulators , movabl e insulatio n i s no t continuousl y resistan t t oheat flo w throug h glazing , bu t i s close d intermittently , particularl yat night , t o reduc e outwar d hea t losse s withou t sacrificin g sola rgains . Consequentl y i t require s a shuttere d glazin g o f greate r ther -mal resistanc e t o equa l th e energ y conservatio n potentia l o f a trans -paren t insulato r whos e effec t i s continuous . Fo r exampl e i t i s show ni n Appendi x A tha t o n a n annua l basi s doubl e glazin g plu s therma lshutter s yieldin g a tota l resistanc e o f 0.7 8 m2°C/ W ar e require d t omeet th e performanc e o f tripl e glazin g wit h a resistanc e o f 0.5 5m2°C/W. Nevertheles s certai n shutte r system s ar e capabl e o fimpartin g wall-lik e overal l therma l resistance s t o glazin g systems .

Concern s abou t th e convenienc e o f operatin g movabl e insulatio n an dthei r abilit y t o integrat e wit h windo w layou t withou t interferin g wit hth e us e o f spac e adjacen t t o th e windo w hav e spawne d many alternativ emovabl e insulatio n strategie s (111 , 112 , 113 , 114) . Whil e movabl einsulatio n system s ar e a recen t developmen t an d hav e no t bee n full yexplore d no r integrate d wit h windo w desig n i t woul d appea r tha t th eflexible , fol d o r roll-u p typ e o f syste m fitte d t o th e interio r o f awindo w wit h a positiv e ai r sea l offer s th e mos t convenienc e o f opera -tion , flexibilit y i n fi t an d freedo m fro m spatia l conflic t fo r th eleas t amoun t o f money . Howeve r i t i s beyon d th e scop e o f thi s pape r t orevie w al l th e differen t type s o f therma l shutter s o r windo w managementdevice s whic h hav e bee n develope d excep t t o not e tha t despit e thei rpotentia l t o reduc e hea t flo w throug h glazin g i n bot h ne w an d existin gbuildings , fe w i f an y therma l shutter s ar e currentl y produced , markete dor sol d i n Canada . Th e Nationa l Researc h Counci l ha s solicite d propos -al s fro m Canadia n windo w manufacturer s fo r th e developmen t o f energ yconservin g system s fo r residentia l window s (115 ) bu t a s ye t i t i s to oearl y t o anticipat e an y result s fro m thes e studies .

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6.3 HEAT STORAGEThe problem in utilizing large quantities of direct solar heat gainslies in storing the heat within the building over a narrow temperaturerange and with a minimum of mechanical apparatus. Yet the vernacularof Canadian low-rise residential construction is woodframe and drywall- almost the extreme in lightweight, low thermal capacitance construc-tion. Other than active methods for heat storage and distribution thissuggests that it will be necessary to re-introduce and extend the useof high thermal capacitance materials within the building interior.Many of these materials are traditional: masonary, concrete, plaster,quarry tile and even gypsum drywall.

New 'isothermal storage' materials are under development which utilizethe latent heat of fusion of eutectic salts for heat storage. 'Thermo-crete', developed by Suntek Research Associates (116) uses a eutecticof calcium chloride decahydrate dispersed in a concrete which acts toinhibit phase separation of the eutectic. The 'Sol-ar-tile' developedat the Massachusetts Institute of Technology uses thin layers of sodiumsulphate decahydrate with sodium chloride within a precast polyestertile (117). These tiles have undergone more than 2000 freeze-thawcycles without degradation and are installed in Solar Building 5 atthe Massachusetts Institute of Technology to absorb surplus directsolar gains through glazing (118). Their latent heat storage capacityis 25.3 kJ/kg at 23°C which compares to 0.92 kJ/kg°C for concrete.

6.4 VARIABLE SHADING DEVICESA number of products have been developed which, in order to preventoverheating vary the flow of solar radiation through glazing. TheM.I.T. glazing system uses a silvered version of the Pella 'Slimshade'in order to shade or redirect solar radiation onto the celling (as inreferences 107, 118). Suntek has developed a novel material called'Cloud Gel' which is a 90% transparent plastic film that turns whiteand only 20% transparent above a given room temperature which can beset at any value between 10 and 90°C (see 110).

6.5 GADGETRYIn addition to the refinement of building materials and components theuse of passive solar heating may also involve the development ofcertain mechanical products. These include:

-

-

differentia l temperatur e control s an d activ e hea t transfe r system swhic h facilitat e th e redistributio n o r storag e o f passiv e sola rheat gain s independen t o f auxiliar y hea t supply ;

automatic , synchronou s shutters ;

- ai r t o ai r hea t exchanger s fo r hea t recover y o f ventillate d ai r i nair-tigh t residentia l building s (119) , an d

- energ y 'dashboards ' o r detaile d visua l performanc e monitor s fo rresidence s whic h giv e explicit , multi-channe l feedbac k upo n th eoccupant' s us e o f appliances , th e building s auxiliar y hea t supply ,th e building' s passiv e sola r behaviour , an d outdoo r weathe rconditions .

79

7. BUILDIN G STANDARDS

7. 1 GENERALWhil e al l building s ar e passiv e sola r heate d t o a n exten t i t i s neces -sar y t o identif y thos e characteristic s tha t mak e a 'passiv e sola rheate d building ' mor e s o tha n most , an d thereb y establis h standard sfo r th e constructio n o f passiv e sola r heate d buildings . Thes e passiv esola r standard s may no t ye t supplan t existin g energ y conservatio n stan -dard s i n building s bu t wil l serv e t o guid e th e desig n an d constructio nindustr y t o implemen t a mor e energ y conservin g an d appropriat e product .At th e sam e tim e the y wil l protec t th e consume r fro m misleadin g promo -tio n an d th e misus e o f passiv e sola r desig n technique s resultin g i ninsufficien t passiv e sola r performanc e o r physiologica l discomfort .

The traditiona l approac h t o buildin g standard s i s t o prescrib e th eminimu m essentia l facilities , area s an d dimension s t o b e provide d i n abuildin g an d th e minimu m essentia l physica l propertie s o f th ematerials , system s an d component s t o b e use d i n th e assembl y o f abuilding . Suc h prescriptiv e standard s ar e readil y graspe d b y th ebuildin g industr y a s the y ar e explici t an d direc t i n application ,requirin g little , i f an y intermediar y translatio n o r calculation .

However th e proble m wit h suc h piec e b y piec e prescriptiv e therma lstandard s i s tha t the y d o no t directl y ensur e th e adequat e performanc eof th e buildin g a s a whol e - i t bein g simpl y assume d tha t i f al l th epart s o f th e buildin g mee t o r excee d prescribe d minimu m standard s the nth e therma l performanc e o f th e entir e buildin g wil l b e acceptable .

Thi s i s no t th e cas e i n a direc t gai n passiv e sola r heate d buildin gwher e discomfor t du e t o overheatin g wil l occu r whe n th e therma lstandard s o f th e buildin g envelop e and/o r th e are a o f south-facin gglazin g ar e increase d beyon d certai n levels .

Of cours e th e solutio n t o overheatin g i s t o increas e th e effectiv etherma l capacitanc e o f th e buildin g interior , bu t a s th e determinatio nand refinemen t o f therma l capacitanc e i s interdependen t wit h th e ther -mal integrit y an d glaze d are a o f a buildin g i t i s no t amenabl e t o asimpl e ite m b y ite m prescriptiv e definition . Additionall y th e deter -minatio n o f th e therma l capacitanc e o f th e buildin g interio r i s no t awel l establishe d practic e an d it s requiremen t may prov e inhibitin g t oth e broade r constructio n industry . On th e othe r han d th e solutio n t ooverheatin g i s t o se t limitin g standard s upo n th e therma l characteris -tic s o f th e constructio n an d south-facin g windo w are a whic h ar e tune dt o th e interio r therma l capacitance s associate d wit h conventiona lbuildin g practices . Whil e thi s result s i n a pragmati c standar d i t i sironi c indee d t o limi t bot h th e energy-conservin g an d sola r collectio naspect s o f passiv e sola r heate d building s an d t o d o s o i n deferenc e t oa lo w leve l o f skil l an d innovatio n i n th e buildin g industr y whe n th eopposit e i s desirable .

I n respons e t o thi s somewha t paradoxica l situatio n thi s pape r present sa bi-leve l standar d fo r direc t gai n passiv e sola r heate d building s i nCanada. I n th e interes t o f simplicit y an d rapi d wide-sprea d adapta -bility , th e firs t leve l i s a straightforwar d ite m b y ite m prescriptio n

of minimu m standards . I t ensure s adequat e passiv e sola r performanc ebut doe s no t requir e th e determinatio n o r adjustmen t o f th e therma lcapacitanc e o f th e buildin g interior . Howeve r a simpl e calculation ,derive d fro m standar d ASHRAE method s fo r sizin g th e maximu m hea t loa dof a building , i s require d t o ensur e tha t th e overal l therma l integrit yof th e buildin g meet s a give n standar d an d then , relativ e t o thi s stan -dard , t o determin e th e limitin g south-facin g glaze d are a o f a building .

The secon d leve l o f th e passiv e sola r standar d i s t o b e applie d when -eve r th e south-facin g windo w are a o f a buildin g i s t o excee d th e limit -in g are a determine d i n leve l one . I t prescribe s a metho d t o determin eth e require d therma l capacitanc e o f th e buildin g interio r interdepen -dent wit h bot h th e are a o f south-facin g glazin g an d th e therma l stan -dard s o f th e building . I t als o limit s th e material s an d thei r respec -tiv e temperatur e range s whic h may b e use d i n providin g th e require dtherma l capacitanc e o f th e buildin g interior .

7. 2 LEVEL ONE: PASSIV E SOLAR STANDARD1. 1 SCOPE1.1. 1 Thi s standar d i s intende d t o appl y t o building s whic h utiliz e

direc t passiv e sola r gain s throug h windo w an d sunspac e system si n orde r t o reduc e thei r ne t heatin g loa d an d whic h hav e a lo wrat e o f interna l hea t gain . Thi s shoul d includ e mos t low-ris eresidentia l buildings , an d motels .

1.1. 2 A lo w rat e o f interna l hea t gai n i s define d a s equa l t o o r les stha n 20W/m 2 floo r are a o f th e building , wher e th e interna lheat gai n rat e i s determine d a s th e averag e interna l hea t gai nrat e ove r a 1 6 hou r 'day ' du e t o expecte d occupanc y an d th eexpecte d us e o f lights , appliance s an d othe r apparatus . Al lsensibl e an d laten t hea t gain s fro m people , pumps , fans , motors ,light s an d appliance s contribut e 100 % t o interna l hea t gain sexcep t thos e appliance s whic h ven t o r drai n t o th e exterior .Then, unles s fitte d wit h a hea t recover y device , th e followin gar e th e prescribe d maximu m ne t contributio n rate s t o interna lheat gai n resultin g fro m th e operatio n o f a :

hot wate r heate r (120 ) 40 %ventilate d stove/oven ;

dishwashe r o r clothe s washer ; 50 %

clothe s dryer . 20 %

1. 2 OPAQUE ASSEMBLIES1.2. 1 Th e requirement s o f thi s sectio n may b e relaxe d wher e i t ca n b e

shown tha t complianc e wit h sectio n 1.5 , Loa d Are a Ratio , i smaintained .

80

81

1.2. 2 Accountin g fo r an y therma l bridgin g effects , al l opaqu e assem -blie s o f th e buildin g envelop e separatin g a heate d spac e fro man unheate d space , outdoo r air , o r adjacen t eart h shal l hav eth e followin g minimu m therma l resistances :

Minimu m Resistanc e

1. 3 INFILTRATIO N AND VAPOUR BARRIE R1.3. 1 Window s an d door s shal l b e designe d t o limi t th e rat e o f ai r in -

filtratio n a s specifie d i n Sectio n 3.5 , Infiltration , 'Measure sFor Energ y Conservatio n i n Ne w Buildings , 1978' , NRCC No . 16574 .

1.3. 2 Joint s betwee n th e sil l plat e an d th e foundation , th e to p plat eand th e ceiling , a t wal l corners , aroun d windo w an d doo r frames ,and an y othe r locatio n wher e ther e i s a possibilit y o f ai r leak -age int o heate d space s i n a buildin g throug h th e exterio r wall ssuc h a s utilit y servic e entrances , shal l b e caulked , gaskete dor seale d t o restric t suc h ai r leakage .

1.3. 3 A vapou r barrie r shal l b e installe d o n th e war m sid e o f insula -tion , o r a t a poin t i n th e insulatio n warme r tha n th e de w poin tof th e interio r air , calculate d unde r stead y stat e condition sand January , 2 1/2 % outdoo r temperature . Th e vapou r barrie r i st o consis t o f a t leas t 4 mil . polyethylen e an d i s t o b e lapped ,caulke d o r otherwis e continuousl y sealed , th e sam e aroun d al lperforation s fo r windows , doors , servic e conduits , electrica loutlets , an d abuttin g interio r floor s an d partitions .

1. 4 GLAZIN G1.4. 1 Glazin g i s define d a s an y transparen t o r translucen t materia l

separatin g a heate d spac e fro m outdoo r ai r an d use d t o transmi tligh t an d sola r radiatio n withi n a building .

Componentm2°c/ W ft 2° F hr/BT U

i )

ii )

iii )

iv )

v)

vi )

vii )

Roof-ceilin g

Wall s abov e grad e

Door s

Floor s ove r crawlspac e

Sla b o n grad e

Wall s belo w grad e 1s t 600m m

res t

Sla b o r floo r belo w grad e

8. 5

4. 6

1. 6

3. 2

2. 3

3. 2

2. 3

1. 8

48

26

9

18

13

18

13

10

82

1.4. 2 Eligibl e glazin g system s are :i ) tripl e glazin g wit h tw o airspace s no t les s tha n 1 2 mm

thicknes s each , havin g a n overal l therma l resistanc e no tles s tha n 0.5 2 m2°C/W;

ii ) doubl e glazin g wit h a n airspac e no t les s tha n 1 2 mmthicknes s an d a movabl e insulatio n syste m th e combine dtherma l resistanc e o f whic h i s no t les s tha n 0.8 0 m2°C/W;

iii ) an y othe r glazin g withou t movabl e insulatio n tha t ha s a noveral l therma l resistanc e no t les s tha n 0.5 2 m2°C/W.

1.4. 3 A t leas t 75 % o f th e glazin g are a shal l b e south-facing .South-facin g glazin g mus t satisf y al l o f th e followin g criteria :

i ) compl y wit h sectio n 1.4. 2 an d hav e a transmittanc e t o bea mradiatio n a t norma l incidenc e no t les s tha n 60%. Thi s i sequivalen t t o a n ASHRAE Shadin g Coefficien t o f no t les stha n 70%;

ii ) b e oriente d wit h + 45 ° azimut h o f du e south ;

iii ) b e slope d mor e tha n 45 ° fro m horizontal ;

iv ) b e unshade d b y an y coniferou s tree , building , roo f over -hang , o r latera l projectio n o f th e sam e buildin g whil e th esun i s withi n + 45 ° azimut h o f du e sout h o n Decembe r 21 ;

v) b e shade d fro m bea m radiatio n b y louvers , blinds , deciduou strees , trellis , o r roo f overhan g a t noo n o n Jun e 21 .

1.4. 4 Excep t a s provide d i n Leve l Two o f thes e standards , th e south -facin g glazin g shal l no t excee d a n are a equa l t o te n percen t o fth e finishe d floo r are a o f a buildin g time s th e fractiona lproportio n o f th e Loa d Are a Rati o o f th e buildin g (a s define di n sectio n 1.5 ) t o th e referenc e Loa d Are a Rati o o f 1. 5 W/° Cm2 floo r area .

i.e . Limitin g are a o f south-facin g glazin g = RL C x .1(FFA )

wher e RL C = Referenc e Loa d Coefficien t

= Loa d Are a Rati o o f buildin g1. 5 W/° C m2 floo r are a

FFA = finishe d floo r are a o f th e buildin g an d i sexclusiv e o f exterio r walls , unheate d space s an dunfinishe d basement .

1.4. 5 Excep t a s allowe d i n sectio n 1.4.6 , th e non-south-facin gglazin g o f a buildin g shal l no t excee d a n are a equa l t o 1/ 3 o fth e south-facin g glazin g area .

83

1.4. 6 Th e are a o f non-south-facin g glazin g may b e increase d b y a namount proportiona l t o an y increas e i n th e therma l resistanc eof th e non-south-facin g glazin g wit h respec t t o th e minimu mresistance s outline d i n sectio n 1.4.2 , an d then , onl y whe n i ti s show n tha t an y glazin g oriente d withi n + 45 ° azimut h o f du ewest i s shade d externall y fro m bea m radiatio n b y reflectiv efilm , blinds , awnings , trees , othe r building s o r architectura lprojections , wit h a Shadin g Coefficien t no t greate r tha n 35%,at 16:0 0 hours , standar d time , o n Jul y 21 .

1. 5 LOAD AREA RATI O1.5. 1 Th e Loa d Are a Rati o o f th e buildin g mus t no t excee d a referenc e

valu e o f 1. 5 W/° C m2 floo r area .

1.5. 2 Th e Loa d Are a Rati o o f a buildin g i s define d a s th e overal ldegree-hou r conductanc e rat e o f a buildin g divide d b y th efinishe d floo r are a o f th e building .i.e . LA R = MHL x 1_

DTD FF A

wher e MHL = th e Maximu m Hea t Loa d o f th e buildin g obtaine d b ystandar d ASHRAE methods . Als o th e maximu m hea t loa d i s t o b edetermine d independen t o f th e effec t o f an y shutter s o r movabl einsulatio n whic h woul d no t b e close d o n clea r winte r days .Unles s show n t o b e otherwise , th e ai r chang e rat e use d i n deter -minin g th e maximu m hea t loa d o f a buildin g shal l no t b e les stha n 0. 5 time s th e volum e o f ai r containe d withi n th e buildin gtha t lie s abov e grade , pe r hour . When th e requirement s o fsectio n 1.3 , Infiltratio n an d Vapou r Barrier , ar e full y adhere dt o an d a n ai r t o ai r hea t exchange r i s installe d t o recove r hea tfro m mechanicall y ventillate d air , th e ai r chang e rat e shal l no tbe les s tha n 0.2 5 time s th e volum e o f ai r containe d withi n th ebuildin g tha t lie s abov e grade , pe r hour .

DTD = th e Desig n Temperatur e Differenc e betwee n th e indoo rdesig n temperatur e an d th e Januar y 2 1/2 % outdoo r temperature .

FFA = th e finishe d floo r are a a s define d i n sectio n 1.4.4 .

1. 6 MECHANICAL1.6. 1 A passiv e sola r heate d spac e o f a buildin g mus t b e service d b y

a syste m capabl e o f distributin g th e sola r hea t gai n throughou tth e remainde r o f th e buildin g o r removin g th e sola r hea t gai nt o a therma l storag e unit .

1.6. 2 Th e hea t recovery/distributio n syste m shal l b e a n active ,(forced ) ai r o r liqui d syste m unles s i t ca n otherwis e b edemonstrate d t o functio n b y a natura l thermosiphonin g process .

1.6. 3 Wher e th e hea t recovery/distributio n syste m i s par t o f th e back -up heatin g syste m i t mus t b e capabl e o f operatio n independen t o fth e hea t suppl y function .

1.6. 4 Th e hea t recovery/distributio n syste m shal l b e operabl e whe n th etemperatur e o f th e sout h are a o f th e buildin g rise s abov e th eset poin t temperatur e o f th e heatin g syste m an d may b e con -trolle d b y a differentia l temperatur e senso r o r manua l switch .

1.6. 5 Th e se t poin t temperatur e o f th e heatin g syste m shoul d no texcee d a temperatur e o f a t leas t 6° C belo w th e temperatur e a twhic h th e occupan t woul d fee l sufficientl y uncomfortabl e s o a st o ope n windows .

1.6. 6 When a passiv e sola r heate d buildin g i s equippe d wit h a coolin gsyste m whic h doe s no t involv e hea t recovery , thermostat sdesigne d t o contro l ai r temperatur e shal l hav e a t leas t 6° Cseparatio n betwee n th e operatio n o f heatin g an d coolin gequipment .

1. 7 USER' S MANUAL1.7. 1 Th e occupan t o f a passiv e sola r heate d buildin g shal l b e

provide d wit h a 'user's ' manua l explaining :

i ) ho w th e passiv e sola r heatin g syste m works ;

ii ) whe n an d ho w t o operat e movabl e insulatio n an d shadin gdevice s i f suc h ar e provided ;

iii ) whe n t o regulat e th e hea t recovery/distributio n syste mwheneve r suc h i s controlle d b y a manua l switc h and/o rdamper ;

iv ) ho w t o regulat e th e back-u p heatin g syste m se t poin t an dset bac k temperature s i n orde r t o maximiz e th e contribu -tio n o f passiv e sola r hea t gain s withou t overheating .

7. 3 LEVEL TWO: PASSIV E SOLAR STANDARD2. 1 Complianc e wit h Leve l Two : Passiv e Sola r Standar d i s require d

wheneve r th e south-facin g windo w are a o f a buildin g exceed s th elimitin g are a o f south-facin g glazin g a s determine d i n Leve lOne, sectio n 1.4.4 . Complianc e wit h al l th e othe r section s o fLeve l One : Passiv e Sola r Standar d mus t b e maintained .

2. 2 TOTAL THERMAL CAPACITANCE2.2. 1 Th e Tota l Therma l Capacitanc e (TTC ) o f th e buildin g interio r

shal l b e equa l t o o r greate r tha n th e are a o f south-facin gglazin g time s 680 0 kilo-joule s divide d b y th e Referenc e Loa dCoefficien t o f th e building .

84

85

i.e.  TTC  > ASFG x 6800 kJ

RLC

where ASFG  =  the  Area  of  South-Facing  Glazing  measured  in

square meters

RLC  =  the Reference Load Coefficient of the building as

defined in Level One, section 1.4.4.

6800kJ  =  the  minimum  required  thermal  capacitance  per

square meter of south-facing glazing, of a build-

ing with a Load Area Ratio of 1.5 W/°C m2 floor

area.

2.2.2  The Total Thermal Capacitance of a building is calculated as the

sum  of  the  thermal  capacitances  of  each  material  within  the

building interior.

i.e. TTC = Σ TCj

where, j

TCj

where, V

P

SH

dT

= each  different  material  located  within  the

insulated building envelope

= the Thermal Capacitance of each material

= V x p x SH x dT

= the Volume of each material

= the density of the material

= the Specific Heat of the material

= the allowable temperature change in the material

2.2.3  The maximum effective depth (d) and allowable temperature change

(dT)  to  be  used  in  calculating  the  thermal  capacitance  of

materials  contributing to  the Total Thermal Capacitance of the

building interior are set forth below:

Material

i)  all heated air

ii)  any material located within

the building envelope, not

receiving direct beam radiation

Colour  d (mm)

75

dT (°C)

5.6

5.6

j = 1

- -

-

n

86

(cont'd ) Materia l

iii ) an y materia l use d a s hea tstorag e an d couple d t o th e sola rheate d spac e b y a hea t pump

iv ) an y materia l locate d withi nth e buildin g envelope , no tparalle l t o th e sout h glazing ,but receivin g bea m radiatio nat leas t 3/ 8 o f th e day , Jan . 2 1

v) an y materia l locate d withi nth e buildin g envelope , paralle lt o th e sout h glazin g an dreceivin g bea m radiatio n ove rat leas t 3/ 4 o f th e day , Jan . 2 1

Colou r d (mm) dT (°C )

7. 4 ASSUMPTIONS AND LIMITATION SI n orde r t o defin e thes e standard s i t wa s necessar y t o establis h areferenc e relationshi p betwee n th e thre e prim e variable s o f a buildin gwhic h influenc e it s passiv e sola r performance : th e south-facin g glaze darea ; th e therma l capacitanc e o f th e buildin g interior ; an d th e overal ltherma l integrit y o f th e buildin g envelope . Th e specification s o fHouse D i n Appendi x C wer e use d t o identif y th e referenc e parameter s o fa passiv e sola r building . Wit h a sout h facin g windo w are a equa l t o 10 %of th e finishe d floo r area ; a therma l capacitanc e jus t greate r tha n1225 kJ/° C m2 sout h window ; an d a Loa d Are a Rati o o f 1. 5 W/° C m2

floo r are a th e performanc e o f thi s buildin g wa s simulate d o n a clear ,warm Januar y da y i n Ottaw a an d wa s foun d t o b e abl e t o absor b th e ne tpassiv e sola r gai n ove r th e da y wit h a n interna l temperatur e ris e o f6°C. Thi s may o r may no t b e a n adequat e tes t fo r overheatin g ove r th eentir e heatin g season . Howeve r th e dat a derive d fro m thi s hous e ar eclosel y corroborate d b y th e dat a o f othe r researchers , presente d i nsectio n 5.2.1 .

I t i s the n assume d i n th e absenc e o f an y othe r publishe d relationshi ptha t th e limitin g are a o f south-facin g glazin g b e decrease d o r th etherma l capacitanc e o f a buildin g b e increased , linea r wit h an yincreas e i n th e overal l therma l integrit y o f a buildin g wit h respec tt o th e referenc e buildin g parameter s above , i n orde r t o stil l absor bmaximum ne t sola r gain s withi n a 6° C temperatur e swing .

The Loa d Are a Rati o o f a buildin g wa s develope d t o facilitat e th ecompariso n o f th e overal l therma l integrit y o f on e buildin g t oanother . B y expressin g th e overal l therma l loa d o f a buildin g pe runi t floo r area , consistenc y i s establishe d regardles s o f buildin gsize . A t th e sam e tim e therma l efficiencie s du e t o enclosur e geometr yand buildin g scal e ar e accounte d fo r a s wel l a s ar e th e mor etraditiona l cross-sectiona l therma l resistance s o f eac h componen t o fth e buildin g enclosur e envelope .

- - as deter -mine d b yheat pump

ligh t 7 5 1 1

dar k 15 0 1 1

ligh t 15 0 1 1

dar k 30 0 1 1

87

The referenc e therma l standard s wer e se t abov e thos e presente d i n th enew energ y conservatio n cod e (121 ) becaus e highe r therma l standard s ar eclearl y cost-effectiv e a t thi s poin t i n tim e (se e Appendi x C an d sectio n5.2.3) , an d becaus e highe r therma l standard s increas e th e relativ e con -tributio n o f passiv e sola r hea t gain s t o th e hea t suppl y o f a building .Even highe r therma l standards , a s i n Hous e E , Appendi x C appea r t o b ecost-effectiv e no w bu t wer e no t adopte d fo r thes e standard s recognizing ,i f onl y temporarily , th e inerti a o f th e broade r constructio n industry .

Sinc e th e analysi s o f passiv e sola r buildin g performanc e i n Appendi x Cwas undertake n onl y fo r th e Ottaw a climate , th e transferabilit y o f thes estandard s t o othe r location s wit h significantl y differen t climate swarrant s furthe r investigation .

7. 5 BENEFIT SWhil e virtuall y an y degre e o f passiv e sola r heatin g may b e possibl ewithi n thes e standards , th e benefit s o f th e firs t leve l ar e examine dmore particularl y a s i t i s mos t amenabl e t o rapid , widesprea d adoptio nby minimizin g an y technical , appearanc e an d cos t impac t upo n th e desig nand constructio n o f a passiv e sola r heate d dwelling .

Under Leve l One : Passiv e Sola r Standards , a tota l glaze d are a o f u p t o13.3 % o f th e floo r are a o f a buildin g i s permitted . Thi s quantit y o fglazin g i s consisten t wit h tha t generall y foun d i n housin g eliminatin gany incrementa l cos t whic h may b e associate d wit h increase s i n th eglazin g are a o f a building . Whil e a t leas t 75 % o f th e glazin g area , u pt o 10 % o f th e floo r area , mus t b e place d upo n th e south-facin g are a o fa building , thi s doe s no t presen t a seriou s functional , stylisti c o rappearanc e constrain t upo n a building . When th e east/wes t lengt h o f abuildin g i s 50 % greate r tha n th e north/sout h dimension , th e south -facin g wal l are a i s 25 % o f th e floo r are a o f a bungalo w an d 40 % o f th efloo r are a o f a tw o floo r building . The n th e sout h windo w are a unde rLeve l One wil l onl y cove r u p t o 40 % o f th e sout h wal l are a o f abungalo w o r u p t o 25 % o f th e sout h wal l are a o f a tw o floo r house .

The tota l glazin g are a readil y meet s o r exceed s minimu m area s designa -te d b y th e 'Nationa l Buildin g Code ' an d 'Residentia l Standard s Canada' .Throug h section s 3.3.4 , 3.3. 5 an d 3.3.6 , th e ne w code , 'Measure s Fo rEnerg y Conservatio n i n Ne w Building s 1978' , woul d allo w south-facing ,tripl e glaze d window s u p t o a n are a equa l t o 50 % o f th e floo r are a o f abuilding . Effectivel y thi s i s no t a limi t upo n sout h glaze d areas .Thi s are a woul d represen t 125 % o f th e wal l are a o n th e lon g sid e o f th etwo floo r buildin g above .

Any buildin g buil t t o compl y wit h Leve l One : Passiv e Sola r Standard swil l b e amenabl e t o furthe r passiv e sola r performanc e throug h a futur eretrofi t becaus e th e singl e mos t importan t condition , prope r sola rorientation , i s require d i n th e standard . Indee d a n activ e sola rretrofi t woul d b e possibl e wer e thi s eve r economicall y feasibl e o rnecessary .

88

These followin g quantitativ e dat a ar e derive d fro m thos e outline d i nAppendi x C : Technica l Analysis .

As compare d t o a dimensionall y identica l hous e whic h i s buil t t o impend -in g energ y conservatio n standard s (Hous e C 2.5 , Appendi x C ) a home o f100 m2 floo r are a buil t t o meet th e Loa d Are a Rati o o f Leve l One :Passiv e Sola r Standard , bu t stil l wit h glazin g uniforml y distribute dabou t th e building , woul d hav e a 40 % lowe r gros s annua l heatin g energ yrequirement , reduce d b y som e 9,80 0 kWh. Whil e passiv e sola r hea t gain sar e reduce d i n magnitud e b y th e us e o f tripl e glazin g an d a n effectivel yshorte r heatin g seaso n du e t o increase d therma l standards , th e percent -age contributio n o f th e passiv e sola r hea t gai n t o th e gros s annua lheatin g energ y requiremen t rise s fro m 17. 4 t o 22.4 % an d whe n adde d t oth e interna l hea t gain s fro m peopl e an d appliance s thei r combine d con -tributio n t o th e gros s heatin g energ y requiremen t rise s fro m 35. 5 t o49.6%. Th e magnitud e o f th e ne t heatin g loa d met b y th e back-u p heat -in g syste m i s reduce d b y slightl y greate r tha n 50 % o r som e 858 0 kWh/yr .For thi s buildin g th e installe d cos t o f thes e therma l standard s i sestimate d t o b e $1,71 6 o f whic h $29 0 i s th e incrementa l cos t o f tripl eglazin g an d th e balanc e i s th e increase d cos t o f th e therma l an dinfiltratio n resistanc e standard s o f th e enclosur e envelope .

When th e 10m 2 glazin g are a i s al l relocate d upo n th e sout h wal l o fth e buildin g th e annua l magnitud e o f th e contributin g passiv e sola rheat gai n increase s b y 47 % o r som e 166 4 kWh. Whil e th e magnitud e o fthi s energ y savin g i s no t a s grea t a s tha t effecte d b y th e increase dtherma l standard s o f th e buildin g enclosur e envelop e i t shoul d b e note dtha t th e energ y saving s du e t o relocatio n o f th e glazin g are a o f abuildin g i s accomplishe d wit h n o additiona l increas e i n th e constructe dcos t o f th e building , althoug h som e additiona l desig n cost s may b einvolved .

The buildin g i s no w a t th e limi t o f Leve l One : Passiv e Sola r Standard .I n thi s buildin g th e passiv e sola r hea t gai n constitute s 522 7 kWh o r32.9 % o f th e annua l gros s heatin g energ y requirement . A t thi s poin t th epassiv e sola r hea t gain s combine d wit h interna l hea t gain s contribut e60.1 % o f th e gros s annua l heatin g energ y requirement . Thi s bring s th etota l back-u p heatin g suppl y energ y saving s t o 10,24 4 kWh/yr . fro m th esame buildin g buil t t o recentl y propose d energ y conservatio n standard s(121 ) an d wit h uniforml y distribute d glazing . Value d a t 2.4¢/kW h o felectrica l heatin g th e 1s t yea r back-u p heatin g syste m energ y saving samount t o $246 . Thi s represent s a rea l rat e o f retur n slightl y greate rtha n 14 % o n th e $1,71 6 investment , assumin g a discoun t rat e equa l t oth e rea l rat e o f financin g an d a simila r cos t escalatio n rat e i nelectricit y prices . Unde r th e sam e financia l assumptions , an d al lothe r factor s bein g equal , a 2 5 yea r ne t lif e cycl e cos t saving s o f$4,43 4 i s realized .

89

Alternativel y fro m th e poin t o f vie w o f a prospectiv e ne w homeowner ,th e additiona l cos t o f th e home add s $8.1 3 t o th e monthl y carryin gcharg e o f th e home whe n amortize d a t 3 % rea l cos t ove r 2 5 years , or ,$5.7 2 rea l whe n th e paymen t i s discounte d equa l t o th e rea l mortgag erate . Again , escalatin g an d discountin g annua l heatin g energ y cos tsaving s i n a simila r manner , th e heatin g energ y cos t saving s o f th ebuildin g buil t t o Leve l One : Passiv e Sola r Standard , reduc e th e averag emaintenanc e an d ownershi p cos t o f th e buildin g b y $20.5 0 rea l pe rmonth , yieldin g a ne t monthl y savin g i n ownershi p cost s o f $14.78 .Roughl y speaking , i n term s o f home purchasin g power , a n individua l wit h$14.7 8 les s ne t monthl y incom e coul d affor d t o bu y th e home buil t t oLeve l One : Passiv e Sola r Standard , despit e it s highe r cost , tha n coul d

affor d t o bu y th e sam e house , bu t buil t t o existin g energ y conservatio nstandard s wit h uniforml y distribute d glazing . Alternativel y a n indi -vidua l coul d affor d t o purchas e u p t o $6,15 0 mor e house , o n th e sam eincom e whe n th e hous e i s buil t t o Leve l One : Passiv e Sola r Standard .

A. 1

APPENDIX A

MOVABLE INSULATIO N DESIG N CRITERI A

The followin g i s a brie f outlin e o f a minimu m therma l an d cos t specifi -catio n fo r movabl e insulation . I n term s o f conductanc e hea t losse s i ti s calculate d tha t annually , th e effectiv e therma l performanc e o f mov -abl e insulatio n plu s doubl e glazing , a t leas t equa l tha t o f a wel l de -signe d triple-glaze d window , whic h require s n o occupan t control . Fo rsimplicit y th e calculatio n i s mad e independen t o f ai r infiltratio nconsiderations .

The questio n i n determinin g th e year-roun d effectivenes s o f movabl einsulatio n b y simpl e non-dynami c analysis , i s ho w t o accoun t fo r thei rperiodi c us e ove r da y an d nigh t whe n temperature s vary ; an d du e t o th ewhims o f th e operator ?

I t ha s bee n foun d i n Ne w Yor k Cit y tha t 70 % o f th e annua l degre e day soccu r durin g hour s o f darknes s (122) . Probabl y a somewha t highe r fac -to r occur s i n Canad a du e t o longe r winte r nights . Howeve r i t i s doubt -fu l tha t th e buildin g occupan t woul d us e th e shutter s wit h absolut e con -sistency , particularl y i n sprin g an d fal l whe n nevertheless , a consider -abl e numbe r o f degre e day s occur . Accordingl y i t i s assume d tha t th emovabl e insulatio n i s effectiv e ove r on e hal f o f th e annua l degre e days .

I f th e therma l resistanc e o f doubl e glazin g = 0.3 2 m2°C/W,and th e therma l resistanc e o f tripl e glazin g = 0.5 5 m2°C/W,the n th e mea n therma l resistanc e o f th e doubl e glaze d windo w an d th edoubl e glaze d windo w plu s th e resistanc e o f th e movabl e insulatio n (x )must b e equa l t o o r greate r tha n th e therma l resistanc e o f tripl eglazing .

(.3 2 + (.3 2 + x))/ 2 > .5 5 m2°C/ Wx > 0.4 6 m2°C/ W

Thi s represent s th e equivalenc e o f th e followin g material s (123) :

53 mm softwoo d20 mm minera l o r glas s woo l17 mm expande d molde d bea d polystyren e15. 5 mm expande d extrude d polystyren e12 mm expande d polyurethan e

Then a t Ottaw a (551 6 2 1 ° C degre e day s fro m Appendi x C ) th e minimu m R0.4 6 m2 °C/ W movabl e insulatio n (o r tripl e glazing ) woul d save :

((551 6 x 24)/1000 ) (.5 5 - .32 ) = 17 3 kWh/m 2yr ,ove r th e us e o f doubl e glazin g alone . Assumin g a n electri c heatin gcos t o f 2.40¢/ne t kWh th e movabl e insulatio n woul d sav e $4.15/m 2yr , o r$3.17/m 2yr saving s o f No . 2 fue l oi l a t 1.8¢/ne t kWh.

91

92

A. 2

Currentl y i n Ontari o a 1 9 mm shee t o f molde d expande d polystyren e cost s$1.04/m 2 (124 ) indicatin g tha t fo r th e pric e o f th e materia l alone , amovabl e insulatio n o f th e simpl e shutter-typ e o r stick-o n typ e usin gvelcr o o r magneti c clips , coul d b e highl y cost-effective . Howeve r fo rreason s o f convenienc e o f operation , therma l effectivenes s an d archi -tectura l integratio n ther e ar e many othe r approache s t o th e desig n o fmovabl e insulatio n an d cos t factor s additiona l t o th e cos t o f th e insu -latin g materia l ente r th e picture . Thes e include : coverin g th e insula -tin g materia l t o mak e i t bot h durabl e an d attractive ; an y necessar yhangin g hardwar e o r valenc e an d jam b framing ; labour , over-hea d an dprofi t t o produce , marke t an d instal l th e movabl e installation . Whil eno comprehensiv e cos t dat a ar e available , thes e cost s an d particularl yinstallatio n cost s ar e likel y t o b e significant . On th e othe r han dincreasin g th e therma l resistanc e o f movabl e insulatio n woul d hav e apositiv e effec t upo n it s cos t effectivenes s a s manufacturin g an dinstallatio n cost s shoul d no t ris e directl y linea r wit h therma lresistance .

The compariso n o f straigh t doubl e glazing , o r doubl e glazin g plu s mov -abl e insulation , t o tripl e glazin g i s a mor e comple x proces s tha n th eabov e a s th e extr a glas s ligh t decrease s passiv e sola r hea t gains ,effectivel y diminishin g th e ne t therma l benefi t o f tripl e glaze dsystems . Bot h a tripl e glaze d an d a doubl e glaze d windo w wit h a nR 0.46m 2oC/f t movabl e insulatio n woul d sav e a n equivalen t amoun t o fenerg y i n term s o f conductanc e losse s ove r doubl e glazin g alone , how -ever , i f eac h ligh t o f glazin g wer e th e sam e thickness , th e doubl eglazin g plu s movabl e insulatio n woul d transmi t approximatel y 12 % greate rpassiv e sola r gai n tha n tripl e glazing , makin g it , i n stric t therma lterms , th e superio r choice . Agai n greate r shutte r resistance s augmen tth e therma l benefi t o f th e doubl e glazin g plu s movabl e insulatio nsystem . Currently , i n th e Ottaw a area , tripl e glazin g retail s fo r$27.0 0 t o $30.00/m 2 o r approximatel y 20 % greate r tha n th e pric e o fdoubl e glazin g alon e (125) , prescribin g a n uppe r limi t fo r th einstalle d cos t o f a n R 0.46m 2oC/ W movabl e insulatio n system .

93

B. 1

APPENDIX B

NATIONAL RESIDENTIA L PASSIV E SOLAR WINDOW GAIN , 197 5

The calculatio n o f th e magnitud e o f th e nationa l passiv e sola r gai nthroug h glazin g whic h contribute s t o residentia l spac e heatin g i sperforme d fo r 1975 , thi s bein g th e mos t recen t yea r fo r whic h statistic supon tota l domesti c an d far m energ y consumptio n ar e availabl e (126) .Despit e th e fac t tha t remarkabl y littl e analysi s ha s bee n conducte d upo nth e en d us e o f thi s energ y consumption , Energy , Mine s an d Resource sassumes tha t 70 % i s use d directl y fo r spac e heating , 18 % fo r wate rheatin g an d 12 % fo r othe r purpose s (127) . I t i s assume d tha t 1/ 3 o fth e non-spac e heatin g energ y consumptio n actuall y contribute s indirectl yt o residentia l spac e heating . Thu s 80 % o f th e tota l domesti c an d far menerg y consumptio n eithe r directl y o r indirectl y contribute s t o spac eheating . Then , fro m referenc e 5 3 i n sectio n 5.1 , th e calculate dresidentia l spac e heatin g energ y consumptio n represent s 87.5 $ o f th egros s residentia l spac e heatin g requirement , th e remainin g 12.5 % o fwhic h i s supplie d b y passiv e sola r gain s throug h glazing .

Then:Tota l nationa l energ y consumption , 197 5 = 5,886. 2 x

1012BTU (126 )

Tota l domesti c an d far m energ y consumption , 197 5 = 1,162. 7 x1012BTU (126 )

Gros s annua l residentia l heatin g requiremen t(1,162. 7 x 10 12BTU x .8)/.87 5 = 1,063. 0 x 10 12BTU

Contributin g direc t passiv e sola r gai n1063.0 x 1012BTU x .125 = 139.2 x 1012BTU

Percentag e nationa l consumptio n100 (139. 2 x 10 12BTU/5,886. 2 x 10 12BTU) = 2.26 %

Tota l electri c consumptio n al l sectors , 197 5 = 907. 4 x 10 12BTU(126 )

Nuclea r componen t o f eleetrica l production , 197 5 = 4.0 %(128 )

Ratio : Passiv e solar/nuclea r electric , 197 5132. 9 x 10 12BTU/(907. 4 x 10 12BTU x .04 ) = 3.6 6

94

C.1

APPENDIX C

TECHNICAL ANALYSI S

Introductio nThi s stud y wa s undertake n t o quantif y th e contributio n o f passiv e sola rheat gain s throug h window s an d o f th e leve l o f energ y conservatio n stan -dard s o f th e buildin g envelop e towar d reducin g th e us e o f purchase d energ yfo r spac e heatin g i n ne w residentia l constructio n i n Canada . B y comparin gth e additiona l cos t o f installin g increase d south-facin g windo w are a an denerg y conservatio n standard s wit h th e presen t wort h o f futur e energ y cos tsaving s resultin g fro m thes e measures , som e conclusion s may b e reache dconcernin g th e effectivenes s o f passiv e sola r heatin g an d th e leve l o fenerg y conservatio n standard s i n futur e Canadia n residentia l construction .

Al l comparison s wer e made wit h respec t t o a hypothetica l bungalo w wit h abasement whos e outsid e dimension s wer e 11. 9 m b y 8. 4 m. Wit h a volum e o f415 m3 an d a gros s floo r are a o f 10 0 m2 thi s hous e i s representativ eof N.H.A . finance d house s i n Canad a (129) .

Fiv e level s o f energ y conservatio n standard s wer e examined . Th e therma lspecification s o f thes e standard s ar e reviewe d i n Tabl e C 1 fo r eac h are aof th e tes t building . Standard s 'A ' an d 'B ' ar e typica l o f Canadia nresidentia l standard s sinc e 197 0 (130 , 131) . 'C ' represent s th e standard sset recentl y b y th e Associat e Committe e o n th e Nationa l Buildin g Cod e(121) . Th e remainin g tw o standard s are , b y necessity , hypothetica l a sthe y furthe r excee d thos e i n 'C ' above . Th e specification s o f standar d'E ' ar e simila r t o thos e i n th e Saskatchewa n Conservatio n House .

TABLE C1 THERMAL STANDARDS

THERMALCOMPONENT

AREA(m2)

RESISTANCE (m 2K/W)

A B C D E

ai r chang e per hou r

ceilin g

exterio r wal l

b'men t wal l + grad e

window s

door s

b'men t wal l - grad e

basement floo r

. 5

1.9 6

1.6 0

0.3 5

0.3 2

0.3 8

0.6 5

3.1 8

. 5

2.3 8

2.3 8

1.4 8

0.3 2

0.3 8

0.7 0

3.1 8

100. 0

95. 6

16. 2

10. 0

3. 6

76. 7

100. 0

.2 5

5.6 9

3.0 0

1.5 9

0.3 2

0.7 0

0.7 7

3.1 8

.2 5

8.4 5

4.5 8

3.5 2

0.5 5

1.7 6

2.4 7

4.3 5

.125 *

10.4 9

7.0 5

5.2 8

1.00* *

2.6 4

4.2 2

5.5 5

* 62.5 % hea t recover y o f . 2 ai r chang e pe r hou r vi a mechanica lventilation , plu s .0 5 ai r chang e pe r hou r vi a natura l infiltration .

* * R 1.3 6 m2 K/ W shutter s operate d ove r doubl e glazin g o n 1/ 2 o fdegre e days .

95

C. 2

Then fo r eac h leve l o f therma l standard s th e windo w are a o f th ebuilding , initiall y representin g 10 % o f th e floo r area , wa s varie d fro mbein g uniforml y distribute d abou t al l wall s t o bein g entirel y locate dupon th e sout h wal l o f th e buildin g throug h 4 successiv e stages .Thereafte r th e tota l sout h windo w are a wa s increase d throug h 4 mor estage s unti l th e windo w are a wa s doubled . Thes e variation s i n th edistributio n an d are a o f window s ar e summarize d i n Tabl e C2 .

TABLE C 2 WINDOW AREA AND DISTRIBUTIO N

Sout h Windo w T o Windo w Are a b y Orientatio n (m 2)Floo r Are a (%) Sout h Eas t & West Nort h Tota l

2. 5 2. 5 5. 0 2. 5 10. 05. 0 5. 0 3. 3 1. 7 10. 07. 5 7. 5 1. 7 0. 8 10. 0

10. 0 10. 0 - - 10. 012. 5 12. 5 - - 12. 515. 0 15. 0 - - 15. 017. 5 17. 5 - - 17. 520. 0 20. 0 - - 20. 0

I n all , 4 0 combination s o f sout h windo w are a an d energ y conservatio nstandard s wer e analyzed . Ove r a 2 5 yea r lif e cycl e perio d i t wa s foun dtha t al l combination s o f increase d sout h windo w are a an d therma lstandard s increase d beyon d pendin g energ y conservatio n standard s (121 )ar e cos t effectiv e now . Furthermor e th e benefi t t o cos t rati o wa sgenerall y i n exces s o f 2:1 .

Passiv e sola r hea t gain s togethe r wit h interna l gain s fro m peopl e an dapplianc e us e contribute d fro m 2 2 t o 9 9 pe r cen t o f th e gros s annua lheatin g energ y requiremen t o f th e building . Th e lowe r figur e occurrin gfo r standar d 'A ' wit h unifor m windo w distribution , an d th e highes tcontributio n occurrin g fo r standar d 'E ' wit h th e sout h windo w are aequa l t o 20 % o f th e floo r area . I n othe r word s i t i s possibl e t o sub -stantiall y eliminat e th e consumptio n o f purchase d energ y fo r spac eheatin g i n ne w residentia l building s i n Canad a b y stringen t passiv esola r an d energ y conservin g buildin g design . However , i t wa s indica -te d tha t overheatin g woul d occu r o n clea r winte r day s i n house s C , Dand E wit h windo w area s greate r tha n a floo r are a o f 17.5 , 12. 5 an d7.5% respectively . I t wa s no t attempte d t o pric e an y additiona l hea tstorag e capacit y a s woul d b e require d i n thes e building s i n orde r t ominimiz e hea t dumping . Bu t ther e i s sufficien t margi n i n lif e cycl eenerg y cos t savings , typicall y i n exces s o f $4,000 , t o believ e tha tadditiona l mas s storag e coul d b e provide d o n a cos t effectiv e basis .

Sinc e eac h o f th e energ y conservatio n standard s wa s enacte d a s a uni ti t wa s no t possibl e t o prioritiz e th e effectivenes s o f th e individua lenerg y conservatio n strategie s embodie d i n an y particula r standar d

96

C.3

(e.g . th e relativ e meri t o f additiona l wal l insulatio n versu s therma lshutter s versu s a n ai r t o ai r hea t exchange r withi n standar d 'E') .However i t i s possibl e t o discer n th e followin g a s a roug h an d prelimi -nar y rankin g o f passiv e sola r an d energ y conservatio n strategies .

The mos t effectiv e strateg y i s th e relocatio n o f a s muc h o f th e norma lwindo w are a o f a hous e a s possibl e upo n th e sout h wall . Thi s i saccomplishe d wit h n o tangibl e constructio n cos t increase .

The second-mos t effectiv e strateg y i s t o increas e th e therma l specifi -cation s o f th e buildin g envelop e fro m standar d 'C ' t o thos e o f standar d'D' . Thi s provide s a benefit/cos t rati o runnin g i n th e neighbourhoo dof 3:1 .

The third-mos t effectiv e i s essentiall y a dra w betwee n furthe r increas -in g th e therma l specification s o f th e buildin g envelop e t o thos e o fstandar d 'E ' an d furthe r increasin g th e sout h windo w are a beyon d redis -tribution . I n movin g fro m standar d 'D ' t o standar d 'E ' additiona lbenefit s ar e nearl y offse t b y additiona l costs . Similarly , increase si n th e cos t o f providin g additiona l sout h windo w are a largel y offse tth e benefi t o f furthe r heatin g energ y savings .

The calculatio n o f passiv e sola r hea t gain s an d hea t losse s wer e con -ducte d onl y fo r th e Ottaw a climate . Th e sensitivit y o f th e result s t ochang e i n othe r location s wit h significantl y differen t climate s i s un -known. Bu t a s Ottaw a stand s midwa y i n th e rang e o f Canadia n heatin gregime s (a s represente d b y degre e day s belo w 18°C ) th e genera l finding sof thi s stud y shoul d hol d fo r mos t majo r Canadia n locations .

METHODI n orde r t o calculat e th e annua l passiv e sola r hea t gain s an d ne t heat -in g energ y requiremen t o f th e tes t bungalo w a serie s o f programs , deve -lope d b y th e autho r (132 ) wer e ru n upo n a n HP-9 7 programmabl e calcula -tor . Some explanatio n o f th e content s o f thes e program s follows .

Give n th e hour-by-hou r histor y o f outdoo r temperature , windspee d an dsola r radiatio n alon g wit h th e therma l descriptio n o f th e building , on eset o f program s calculate s th e resultan t hourl y indoo r temperatur e o fth e buildin g an d th e quantit y o f hea t whic h mus t b e supplie d o r remove di n orde r t o maintai n th e indoo r temperatur e betwee n prescribe d minimu mand maximu m setpoin t temperature s ove r a 2 4 hou r day . Isotherma l temp -eratur e condition s ar e assume d t o prevai l i n th e indoo r ai r an d finis hmaterial s an d al l th e therma l capacitance s o f th e interio r material sar e associate d wit h th e indoo r temperatur e mode . Althoug h a grea tsimplificatio n o f th e therma l networ k whic h exist s betwee n th e ai r an ddirectl y an d reflectivel y irradiate d materials , thi s i s a fai r repre -sentatio n o f a ligh t coloure d buildin g interior , wit h thi n ( < 75mm)uniforml y distribute d therma l mas s storag e an d wit h goo d convectiv eai r circulation . Sinc e th e progra m contain s onl y a singl e indoo rtemperatur e nod e i t canno t b e use d t o simulat e th e performanc e o fthic k arrangement s o f mas s storag e o r indirec t gai n mas s walls .

97

C.4

Centra l t o th e progra m i s th e calculatio n o f hourl y passiv e sola r hea tgain s throug h windows . Usin g method s outline d b y Li u an d Jorda n (90 )and Duffi e an d Beckma n (133 ) th e hourl y bea m an d diffus e sola rintensitie s ar e calculate d fo r an y surfac e slop e an d orientation .Then th e transmissio n o f bea m radiatio n i s calculate d a s outline d b yWhillie r (134 ) an d tha t o f diffus e radiatio n b y normalizin g th e are aunder th e bea m transmittanc e curve . Finall y th e transmitte d sola rradiatio n i s trace d a s i t decay s t o insignifican t level s du e t oabsorptio n withi n th e buildin g interio r o r du e t o retransmissio n bac kout th e window . Th e spli t betwee n absorptio n an d retransmissio n i sdetermine d a s a functio n o f th e interio r colour , th e dimensionin g o fth e interio r roo m geometr y relativ e t o th e windo w are a an d o f th ediffus e transmittanc e o f th e windo w itself . Assumin g a mean interio rsurfac e sola r absorptanc e o f 50 % th e absorptio n o f transmitte d sola rradiatio n withi n th e tes t bungalo w range d fro m a lo w o f 93 % whe nfitte d wit h doubl e glazin g equa l t o 20 % o f th e floo r area , t o a hig hof 97 % whe n fitte d wit h tripl e glazin g equa l t o 10 % o f th e floo rarea . Als o o f interest , thoug h no t use d i n thi s study , i s th e abilit yof th e sola r intensit y subroutin e t o accoun t fo r bot h th e bea m an ddiffus e shadin g effect s o f a n overhan g abov e a window .

Othe r feature s o f th e progra m include :

- The inpu t o f hea t gain s du e t o huma n respiratio n an d th e us e o flight s an d appliances . Thes e may b e schedule d ove r an y perio d o fth e day .

- The calculatio n o f hea t flo w throug h glazin g wit h th e optio n o foperatin g movabl e insulatio n ove r th e glazing . Thi s may b eschedule d ove r an y perio d betwee n sunse t an d sunrise .

- The calculatio n o f hea t flo w throug h al l opaqu e component s o f th ebuildin g envelop e locate d abov e grade , b y indoor/outdoo r tempera -tur e difference s only . Externa l sol-ai r temperature s no r th e ther -mal capacitanc e o f th e envelop e constructio n ar e represented .

- The calculatio n o f hea t flo w du e t o bot h win d an d stac k pressure dai r infiltration . Th e progra m als o calculate s hea t flo w du e t oforce d ventilatio n whic h may b e schedule d ove r an y tim e period .

- The calculatio n o f hea t flo w belo w grad e a s a functio n o f indoo rai r an d groun d temperatur e differences . Groun d temperature s wer ecalculate d a t an y dept h an d tim e o f yea r b y method s simila r t othos e outline d b y Gol d an d William s (135 ) an d var y wit h differin gsoi l type s an d groun d moistur e content .

Ideall y thi s typ e o f dynami c analysi s coul d b e use d t o determin e th eyear-lon g passiv e sola r contributio n an d heatin g energ y requiremen t o fth e bungalow , bu t o n a programmabl e calculato r thi s i s fa r to o cumber -some a tes t t o operat e ove r 36 5 days . Anothe r progra m wa s use d fo rthi s purpos e whic h i s describe d furthe r i n th e text . Instea d th e pro -gra m wa s use d t o tes t eac h variatio n o f th e bungalo w fo r overheatin gi n mid-winter . Thi s i s th e tim e whe n heatin g energ y i s wort h a premiu m

98

C.5

and shoul d no t b e wasted . Unfortunatel y th e tim e wa s no t availabl e t otes t fo r overheatin g a t othe r time s o f th e yea r no r t o tes t fo r th eeffectivenes s o f a n overhangin g shadin g device .

Not e tha t th e followin g dat a ar e i n Britis h Unit s sinc e thi s i s th emode o f th e program . Th e minimu m an d maximu m setpoin t temperature swer e se t a t 68° F an d 78° F respectively . Meteorologica l dat a fo r 1 5January , 197 6 wa s used . Althoug h th e outdoo r temperatur e dat a mayappea r coo l the y ar e i n fac t mil d fo r a da y o f maximu m sola r irradianc ei n Januar y i n Ottawa . Th e calculate d therma l capacit y o f th e interio rof th e bungalo w i s reviewe d i n Tabl e C3 .

TABLE C3 THERMAL CAPACITY OF HOUSE

NOTE: N o basemen t material s include d

MASS THERMAL CAPACITYITE M (lb ) (BTU/°F )

wood: interio r partitions,floo rsheathing , finish , door s 468 7 281 2

wood: counters , shelving ,furnitur e 150 0 90 0

drywal l (1 2 mm) 968 7 250 9hardwar e 80 0 9 6ai r 118 0 28 3

TOTAL 660 0

99

Tabl e C 4 document s th e outpu t o f th e progra m i n tabula r for m fo r Bunga -lo w E wit h a south-facin g windo w are a equa l t o 10 % o f th e floo r area .

TABLE C 4 PERFORMANCE SIMULATIO NHouse 'E '

Sout h Window : Floo r Are a = 105 615 January , 197 6

Outdoo r Interna l Passiv e Auxiliar y Indoo rTemperatur e Gain s Gain s Suppl y Temperatur e

Hour (°F ) (BTU/H ) (BTU/H ) (BTU/H ) (°F )

8 -2. 0 3,41 2 20 0 7,57 1 68. 09 -1. 0 3,41 2 15,93 4 0 69. 3

10 1. 8 3,41 2 22,36 1 0 71. 511 5. 8 3,41 2 25,26 8 0 74. 112 10. 2 3,41 2 25,72 7 0 76. 713 14. 2 3,41 2 25,72 7 -8,56 9 78. 014 17. 0 3,41 2 25,26 8 -16,53 6 78. 015 18. 0 3,41 2 22,36 1 -13,69 3 78. 016 17. 8 3,41 2 15,93 4 -7,25 5 78. 017 17. 3 3,41 2 20 0 0 76. 718 16. 5 3,41 2 0 0 75. 419 15. 4 3,41 2 0 0 74. 220 14. 0 3,41 2 0 0 73. 421 12. 5 3,41 2 0 0 72. 622 10. 7 3,41 2 0 0 71. 923 8. 9 3,41 2 0 0 71. 124 7. 1 0 0 0 70. 0

1 5. 3 0 0 0 68. 92 3. 5 0 0 1,07 6 68. 03 2. 0 0 0 6,96 4 68. 04 0. 6 0 0 6,97 9 68. 05 -0. 5 0 0 6,99 1 68. 06 -1. 3 0 0 7,00 0 68. 07 -1. 8 0 0 7,00 6 68. 0

Not e tha t a considerabl e amoun t o f th e passiv e sola r hea t gai n wa sdumped i n orde r t o preven t indoo r temperature s fro m risin g abov e 78°F .Similarl y i t wa s indicate d tha t overheatin g woul d occu r i n house s C , Dand E wit h windo w area s greate r tha n a floo r are a o f 17.5 , 12. 5 an d 7.5 %respectively . I n succeedin g table s thes e variation s pron e t o overheat -in g ar e shade d in , t o serv e a s a n indicato r tha t the y requir e additiona linterio r mas s storag e t o absor b maximu m mid-winte r passiv e sola r hea tgain s withi n comfort .

A secon d se t o f program s wer e use d t o calculat e th e yea r lon g perfor -mance o f th e tes t building . Usin g mean monthl y temperatur e an d sola rradiatio n dat a stead y stat e condition s wer e assume d ove r monthl y tim eincrement s i n orde r t o calculat e al l th e component s o f th e building sheat los s an d suppl y fo r eac h mont h o f th e year . The n th e result s o fal l 1 2 month s o f th e yea r wer e summed t o provid e th e annua l therma lperformanc e profil e o f th e building .

100

C.7

Instea d o f usin g a n artificiall y lo w indoo r balanc e heatin g temperatur eas i n conventiona l hea t los s analysis , a rea l indoo r temperatur e o f 21° Cwas use d i n orde r t o calculat e th e monthl y gros s hea t los s o f th ebuilding . Thes e hea t losse s ar e met firs t b y interna l hea t gains , the nby passiv e sola r hea t gain s throug h window s an d whe n bot h o f thes e ar enot sufficien t t o equilibrat e gros s hea t losse s th e auxiliar y heatin gsyste m supplie s th e remainder , i.e .

gros s hea t los s = interna l gain s+ passiv e sola r gain s+ auxiliar y hea t supply .

Any interna l o r passiv e sola r hea t gain s exceedin g a particula r month' sgros s hea t requiremen t ar e dumpe d an d d o no t recko n i n th e hea t suppl yof tha t mont h o r an y othe r month .

The gros s monthl y hea t los s o f th e buildin g consiste d o f fou r parts .The hea t flo w throug h window s an d tha t du e t o ai r infiltratio n wer ecalculate d a s simpl e function s o f th e mean monthl y indoor/outdoo r ai rtemperatur e differences . Th e calculatio n o f hea t flo w throug h th eopaqu e component s o f th e buildin g envelop e locate d abov e grad eaccounte d fo r th e effec t o f absorbe d sola r radiatio n i n raisin g th eoute r surfac e temperatur e o f th e buildin g abov e tha t o f th e outdoo r ai rtemperature . A s outline d b y ASHRAE (136 ) 2 4 hou r sol-ai r temperature swere calculate d fo r 8 point s o f th e compas s an d the n average d t o produc ea mean dail y sol-ai r temperatur e fo r eac h month . Usin g a surfac eabsorptanc e o f 60 % an d a shad e transmissio n facto r o f 70 % th e meanmonthl y outdoo r temperatur e wa s effectivel y raise d approximatel y 1° C i nDecember t o jus t greate r tha n 2° C ove r th e summer months . Thes e sol-ai rtemperature s ha d onl y a smal l impac t upo n reducin g th e gros s hea t los sof a buildin g - typicall y i n th e neighbourhoo d o f 4%. A t bes t thes esol-ai r temperatur e increase s coul d hav e bee n double d usin g black ,unshade d buildin g surfaces .

Heat flo w throug h basemen t wall s an d floor s wer e calculate d a s a func -tio n o f mean monthl y indoo r an d groun d temperatur e differences . Monthl ytemperature s wer e calculate d an d average d i n th e groun d adjacen t t obot h basemen t wall s an d floors , th e widt h o f th e floo r addin g t o it sequivalen t dept h undergound . Th e groun d underneat h th e basemen t floo rslab , alon g a 90 ° ar c t o a poin t directl y beneat h th e basemen t wal l wa sassumed t o contribut e t o th e therma l resistanc e o f th e basemen t floor ,largel y establishin g th e resistanc e value s i n Tabl e C1 .

Interna l hea t gain s resultin g fro m huma n respiratio n an d th e us e o flight s an d appliance s whic h wer e neithe r vente d o r draine d ou t th ebuildin g wer e se t a t 0. 9 k W ove r 1 6 hour s o f eac h day .

Method s fo r calculatin g mean daily , an d i n turn , monthl y bea m an d dif -fus e sola r radiatio n fo r surface s o f an y slop e withi n 45 ° orientatio nof du e sout h hav e bee n presente d b y Klei n (137) . Thes e ar e readil ymodifie d t o calculat e th e monthl y radiatio n inciden t upo n vertica l

101

C.8

surface s o f an y orientation . The n th e transmissio n o f bea m radiatio ni s calculate d a s a functio n o f th e transmissivit y o f th e windo w glaz -in g a t norma l incidenc e an d th e transmissio n o f diffus e radiatio n i scalculate d a s a functio n o f th e transmissivit y o f th e windo w glazin gintegrate d an d normalize d ove r al l incidenc e angles . No othe r shadin geffect s wer e involved . A s i n th e previou s progra m th e tota l monthl ypassiv e sola r hea t gain s wer e lowere d 3 t o 7% t o accoun t fo r th e re -transmissio n o f reflecte d radiatio n bac k ou t th e windows .

A sampl e outpu t o f th e progra m i s presente d i n Tabl e C5 . Table s C6 ,C7, C 8 an d C 9 lis t th e gros s hea t loss , auxiliar y hea t supply , per -centag e hea t suppl y b y passiv e sola r gains , an d percentag e hea t suppl yby bot h passiv e sola r an d interna l hea t gains , respectivel y fo r al lvariation s o f th e tes t building .

TABLE C5 MONTHLY THERMAL PERFORMANCE PROFIL EHouse 'D '

Sout h Window : Floo r Are a = 10 %

kWhMont h Gros s Interna l Passiv e Sola r Auxiliar y

Heat Los s Hea t Gai n Hea t Gai n Hea t Suppl y

1 271 4 44 6 71 2 155 62 237 1 40 3 75 2 121 63 213 7 44 6 83 9 85 24 142 2 43 2 55 6 43 45 88 7 44 3 44 3 06 37 3 21 6 15 7 07 12 8 12 8 0 08 20 5 20 5 0 09 54 9 27 5 27 5 0

10 105 8 44 6 59 5 1 711 162 6 43 2 38 1 81 312 242 5 44 6 51 7 146 2

Tota l 1589 3 431 8 522 7 634 9

102

C.9

TABLE C6 GROSS HEAT LOSS

kWh/yr .

House Sout h Window/Floo r Are a (%)2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0

A

B

C

D

E

44,791

36,152

25,727

15,893

9,629

44,791

36,152

25,727 25,727

15,893 15,89315,893

9,629

25,727 26,653 27,580

47,306

38,932

48,101

39,72738,00637,079

45,58544,79144,791

36,152 36,152

46,380

AUXILIARY HEAT SUPPLYTABLE C7

kWh/yr .

House Sout h Window/Floo r Are a (%)

A

B 26,657 25,996 25,329 24,665 24,146 23,715 23,288 22,754

103

C.1 0

TABLE C 8 HEAT SUPPLY B Y PASSIV E SOLAR GAIN S

%/yr .

TABLE C 9 HEAT SUPPLY B Y PASSIV E SOLAR AND INTERNAL GAIN S

%/yr .

104

C.1 1

COSTS AND BENEFIT SThe capita l cost s o f changin g th e detailin g o f th e constructio n o f th ebuildin g i n orde r t o improv e it s therma l performanc e hav e bee n esti -mated . Onl y th e cost s associate d wit h modifyin g th e buildin g beyon dstandar d 'C ' wer e considered . Constructio n detai l difference s in -volve d i n movin g fro m standar d 'C ' t o 'D ' an d t o 'E ' ar e outline d i nbrie f i n Tabl e C10 . Refe r t o Tabl e C1 fo r th e therma l resistanc especification s o f eac h standard .

TABLE C1 0 CONSTRUCTION DETAI L BRIE F

Component 'C ' 'D' 'E'

ai r chang e — — 6 mi l continuou svapou r barrie r an dcounter-flo w ai r t oai r hea t exchange r

ceilin g — ad d glas s ad d glas s fibr efibr e

exterio r wall s 2 X 4 , 1 6 " O . C . 2x6 , 24"0.C . doubl e 2x4 , 24"0.C .R12 batt s R2 0 batt s 2 x R2 0 batt s1" poly . 1 1/2"pol y

window s doubl e tripl e doubl e & shutte r

basement wal l concret e woo d & glas s ad d glas s fibr efibr e

basement floo r — ad d poly . bd . ad d pol y bd .

105

Constructio n cost s wer e take n fro m th e Detaile d Uni t Rate s sectio n o fLansdowne' s Constructio n Cos t Handbook , 197 8 an d includ e material ,deliver y an d labou r cost s an d a n additiona l 15 % fo r contractor' sprofit . Windo w cost s wer e establishe d b y a surve y o f loca l retailer s(125 ) an d wer e se t a t $140/m 2, $170/m 2, an d $205/M 2 fo r doubl eglazing , tripl e glazin g an d doubl e glazin g plu s shutter s respectively .Whenever th e windo w are a o f th e buildin g wa s increase d beyon d 10 % o fth e floo r area , cost s wer e adjuste d t o reflec t th e cos t differenc ebetwee n th e particula r wal l an d windo w system .

The benefit s fro m thes e constructio n change s accru e ove r tim e i n th efor m o f auxiliar y heatin g energ y savings . A wid e variet y o f futur eenerg y pric e escalatio n an d financia l discoun t rate s may evolv e makin gi t difficul t t o establis h th e presen t wort h o f thes e futur e energ ysavings . Fo r thi s stud y electricit y wit h a mean 197 8 pric e o f2.40c/kW h wa s use d a s th e purchase d energ y suppl y fo r th e auxiliar yheatin g syste m wit h a lif e cycl e perio d o f 2 5 years . I t wa s assume dtha t th e pric e escalatio n rat e o f electricit y woul d gro w i n rea l term sat betwee n 2 an d 3 % pe r annu m bu t woul d b e discounte d a t th e curren tcos t o f residentia l mortgage s - als o 2 t o 3 % rea l pe r annum . The n th ediscounte d valu e o f futur e energ y saving s woul d sta y constan t i n rea lterm s fo r th e homeowne r wh o ha s amortize d th e margina l cos t o f apassiv e sola r an d energ y conservin g home .

Tabl e C1 1 review s th e additiona l capita l cost s an d 2 5 yea r presen twort h o f futur e energ y saving s fo r al l variation s o f th e tes t buildin gwit h respec t t o th e sam e buildin g buil t t o standar d 'C ' wit h uniforml ydistribute d windows .

TABLE C1 1 BENEFITS AND COSTS$1978 $

(costs )

C.12

106

FOOTNOTES AND REFERENCES

1. "Eve n i n Canadia n cities , wher e i t i s col d occasionally ,commercia l building s mus t discar d twic e a s muc h hea t annuall y a sthe y requir e fro m th e heatin g syste m t o maintai n comfort. "

R.T . Tamblyn , 'Therma l Storage : A Sleepin g Giant' , ASHRAEJournal , June , 1977 , p . 53 .

2. Stev e Harrison , Energ y an d Service s Branch , Divisio n o f Buildin gResearch , Nationa l Researc h Council , persona l communication ,February , 1978 .

3. K.G.T . Hollands , J.F . Orgill , Th e Potentia l fo r Sola r Heatin g i nCanada, universit y o f Waterlo o Researc h Institute , 1977 , pp . 3-5 .

4. J.F . Orgill , Ontari o Ministr y o f Energy , persona l communication ,November , 1977 .

5. anon . 'Potentia l Impac t o f Sola r Heatin g i n th e Residentia lSector' , Ontari o Ministr y o f Energ y Workin g Paper , Augus t 1976 ,p. 9 .

6. H.D . Foster , W.R.D . Sewell , Sola r Home Heatin g i n Canada , Repor tNo. 16 , Offic e o f th e Scienc e Advisor , Departmen t o f Fisherie sand Environment , Ottawa , 1977 , pp . 40-43 .

7. Th e 2n d Nationa l Passiv e Sola r Conference , Philadelphia , Marc h15-19 , 1978 . Proceeding s t o b e availabl e aroun d July , 1978 .

8. Wer e th e Coefficien t o f Performanc e o f sola r heatin g system s t obe define d a s th e rati o o f usable , collecte d sola r energ y t oactiv e energ y inpu t require d t o utiliz e tha t sola r energy , the nth e C.O.P . rang e o f hybri d sola r heatin g system s woul d star tsomewhere beyon d thos e o f activ e system s an d exten d upward stowar d infinity , th e real m o f th e 'pure ' passiv e system .

9. M. Holz , J . Yellot , H . Hay , D . Balcomb , 'Definition s o f Passiv eSystems : Th e Nee d fo r a Supplementa l Terminology' , Passiv e Sola rHeatin g an d Coolin g Conferenc e an d Worksho p Proceedings , May18-19 , 1976 , Albequerque , N.M. , pp . 167-168 .

10. J.D . Balcomb , 'Summar y o f th e Passiv e Sola r Heatin g Conference' ,Passiv e Sola r Heatin g an d Coolin g Conferenc e an d Worksho pProceedings' , May 18-19 , 1976 , Albequerque , N.M. , pp . 2-3 .

11. M. Hol z e t al , ' A Surve y o f Passiv e Sola r Buildings' , America nInstitut e o f Architect s Researc h Corporation , (AIARC) , pp . 17-18 ,1978 .

12. I n additio n t o temperature , physiologica l huma n comfor t relate st o othe r environmenta l factor s suc h a s therma l radiation , ai rmovement an d humidity . See :

107

V. Olgyay , 'Desig n wit h Climate , A Bioclimati c Approac h t oArchitectura l Regionalism' , pp . 14-31 , Princeton , 1963 .

P.O. Fanger , 'Therma l Comfort : Analysi s an d Application s i nEnvironmenta l Engineering' , Ne w York , McGraw-Hil l Boo k Co. , 1972 .

13. Thi s syste m i s t o b e incorporate d i n tw o house s designe d b y Joh nHix , Architec t an d Planner , Toronto . Bot h us e a smal l water/ai rheat pump an d a 120 0 gallo n septi c tan k fo r storage . Th e cos t o fth e syste m installe d i s estimate d a t $3,50 0 ove r a conventiona lcombustio n system . Althoug h muc h smalle r i n scal e th e approac hi s analogou s t o th e 'Therma l Storage ' syste m (se e referenc e 1 )used i n th e Ontari o Hydr o Building , Universit y an d Colleg eAvenues , Toronto .

14. Variation s i n sola r intensity , seasonall y an d b y orientatio n ar eeven mor e pronounce d upo n clea r days . Fo r numerica l value s o fmean dail y sola r radiatio n upo n differen t surfac e tilt s (ever y10° ) an d orientation s (ever y 45° ) a t majo r Canadia nlocations . See :

J.E . Hay , A n Analysi s o f Sola r Radiatio n Dat a fo r Selecte dLocation s i n Canada , Climatologica l Studie s No . 32 , Atmospheri cEnvironmen t Service , pp . 43-10 , Downsview , 1977 .

15. A goo d revie w o f thes e an d othe r shadin g device s an d summar y o fthei r relativ e effectivenes s i s foun d in :

V. Olgyay , A . Olgyay , Sola r Contro l an d Shadin g Devices ,Princeto n Universit y Press , Princeton , 1957 .

Missin g i n th e abov e an d i n mos t literatur e upo n shadin g device sar e dat a upo n o r method s fo r determinin g thei r variabl eyear-roun d effect .

16. Whil e n o well-designe d passiv e sola r buildin g shoul d hav e larg ewest facin g windows , th e followin g i s a n exampl e o f th e economi cbenefi t o f simpl e shadin g devices . Not e tha t o n clea r day s ther ei s n o significan t differenc e o f hourl y direc t norma l sola rintensit y betwee n Canad a an d California .

"Ever y 5 5 squar e fee t o f unshade d west-facin g windo w i n a typica lCentra l Valle y hous e increase s th e ai r conditionin g requiremen tof th e hous e b y approximatel y 12,00 0 BT U pe r hour . Sinc e th epeak hou r o f electrica l deman d i n Californi a correspond s t o th edemand fo r residentia l ai r conditioning , a n extr a to n o f ai rconditionin g (wit h a n energ y efficienc y rati o o f 6 ) wil l increas eth e peak-hou r deman d b y approximatel y 2 kilowatts . Societ y ha s achoic e o f buyin g a n additiona l to n o f ai r conditionin g a t a napproximat e cos t o f $25 0 an d spendin g anothe r $2,00 0 t o increas epeak-hou r generatin g capacit y b y 2 kilowatt s a t a tota l cos t o f$2,250 , o r eliminatin g th e sola r hea t gai n throug h th e window .

108

Shadin g th e windo w wit h a movabl e insulatio n syste m woul d cos tapproximatel y $ 5 pe r squar e foot , a les s efficient , bu t adequate ,syste m usin g a movabl e meta l shad e scree n woul d cos t abou t $1.5 0per squar e foot . A bambo o scree n hangin g fro m a n eav e woul dprobabl y cos t les s tha n 25 ¢ pe r squar e foot . Shadin g th e window ,then , cost s fro m a s muc h a s $27 5 t o a s littl e a s $13.75" .

Penny Niland , Hea d Sola r Technolog y Transfer , Californi a Energ yCommissio n commentin g upo n aspect s o f th e Californi a Sola r Energ yTax Credit , 'Han d i n Hand : Th e Credi t an d th e Codes' , Sola r Age ,June 1978 , p . 31 .

17. G.P . Mitalas , 'Ne t Annua l Hea t Los s Facto r Metho d fo r Estimatin gHeat Requirement s o f Buildings' , Buildin g Researc h Not e No . 117 ,Nationa l Researc h Council , Ottawa , 1976 , Figure s 2 an d 3 .

18. anon. , Greenhous e Industr y 197 5 an d 1976 , Statistic s Canada ,Catalogu e 22-202 , annual , p.30 , Ottawa , Novembe r 1977 .

19. anon. , Import s b y Commodities , Decembe r 1977 , Statistic s Canada ,Catalogu e 65-007 , monthly , Ottawa , March , 1978 .

20. One o f th e mor e notabl e Canadia n development s i n sola r adapte dnorther n greenhousin g i s th e us e o f a n insulate d reflectiv enorther n wal l slope d t o direc t th e lo w winte r su n ont o th e plan tcanop y a s i f fro m overhead . See :

T.A . Lawan d e t al , 'Th e Developmen t an d Testin g o f a nEnvironmentall y Designe d Greenhous e fo r Colde r Regions' , Sola rEnergy , Vol . 17 , 1975 , pp . 307-312 .

21. J . Haye s e t al , 'Proceeding s o f th e Conferenc e o nEnergy-Conserving , Sola r Heate d Greenhouse s a t Marlbor o College ,Vermont , Nov . 19 , 20 , 1977 .

22. J.C . McCullagh , 'Sola r Greenhous e Book' , Rodal e Press , Emmaus,PA. , 1978 .

23. Researc h an d Developmen t Bulletin , Departmen t o f Suppl y an dService s Canada , No . 57 , Dec . 1977 , p . 7 .

24. A.H . Dietz , E.L . Czapek , 'Sola r Heatin g o f House s B y Vertica lSouth-Wal l Storag e Panels' , Heating , Piping , an d Ai rConditioning , Marc h 1950 , pp . 118-125 ; update d a s 'M.I.T . Sola rHouse 2 , South-Wal l Collection , Storag e an d Heating' , Passiv eSola r Heatin g an d Codin g Conferenc e an d Worksho p Proceedings , May18-19 , 1976 , Albequerque , N.M. , pp . 171-182 .

25. Feli x Trombe , e t al , 'Som e Performanc e Characteristic s o f th eCNRS Sola r Hous e Collectors' , Passiv e Sola r Heatin g an d Coolin gConferenc e an d Worksho p Proceedings , May 18-19 , 1976 ,Albequerque , N.M. , p . 220 .

109

26. J.D . Balcom b e t al , 'Simulatio n Analysi s o f Passiv e Sola r Heatin gBuilding s - Preliminar y Results' , Sola r Energy , Vol . 19 , p . 277 ,1977 .

27. ibid , p . 280 .

28. J.D . Balcom b e t al , 'Passiv e Sola r Heatin g o f Buildings ' an d'Rule s o f Thumb' , a s reporte d b y R.P . Stromber g an d S.O . Woodal li n Passiv e Sola r Buildings : A Compilatio n o f Dat a an d Results ,Sandi a Laboratories , Albequerque , N.M. , 1977 .

29. Tw o method s ar e presented . Metho d A , a simplificatio n o f Metho dB, expresse s th e annua l Sola r Heatin g Fractio n supplie d b y apassiv e mas s wal l a s a functio n o f a building' s Loa d Collecto rRati o (i.e . buildin g los s coefficient/sola r collectio n area) . I ti s presente d i n simpl e char t for m fo r 8 4 Nort h American , includin gfou r Canadia n locations . Metho d B i s use d t o determin e th e per -formanc e o f passiv e wal l system s a t othe r locations ; and/o r usin ghorizontal , specula r reflectors ; and/o r o f varyin g therma l load -ing . I t involve s th e summatio n o f monthl y Sola r Heatin g Fraction swhic h ar e i n tur n determine d a s a functio n o f th e monthl y Sola rLoad Rati o (i.e . tota l monthl y sola r energ y transmitte d an dabsorbed/tota l monthl y buildin g load) . Th e abov e metho d i sclaime d t o b e + 3 % accurate , compare d wit h hour-by-hou r compute rsimulation . See :

J.D . Balcomb , R.D . McFarland , ' A Simpl e Empirica l Metho d Fo rEstimatin g th e Performanc e o f a Passiv e Sola r Heate d Buildin g o fThe Therma l Storag e Wal l Type' , submitte d to : Proceeding s o f th e2nd Nationa l Passiv e Sola r Conference , Philadelphia , PA. , Marc h16-18 , 1978 .

30. Kalwal l Corporation , Sola r Component s Division , P.O . Bo x 237 ,Manchester , Ne w Hampshir e 03105 .

31. Sunwall , Inc. , Bo x 9723 , Pittsburg , P A 1522 9

32. Shaw n Buckley , 'Thermi c Diod e Sola r Panels : Passiv e an d Modular' ,Passiv e Sola r Heatin g an d Coolin g Conferenc e an d Worksho pProceedings , May 18-19 , 1976 , Albequerque , N.M., , pp . 293-299 .

33. B . Givoni , a s reporte d i n 'Lo w Cos t Sola r Dwellin g Unde rDevelopmen t i n Israel' , Sola r Energ y Digest , Vol . 8 , No . 1 , p . 1 ,1977 .

31. J.A . O'Leary , F.K . Manase , 'Heliophas e *Sola r Ho t Wate r Heatin gSystem' , Proceeding s o f th e 197 8 Annua l Meetin g o f th e America nSectio n o f th e Internationa l Sola r Energ y Society , Vol . 2.2 , pp .36-40 , Denver , 1978 .

*Registere d Trad e Mar k o f AETA Sola r Inc. , P.O . Bo x 452 , Durham ,N.H.

110

35. Set h D . Silverstein , ' A Dua l Mode Interna l Windo w ManagementDevic e fo r Energ y Conservation' , Energ y an d Buildings , Vol . 1 ,pp. 51-56 , 1977 .

36. Als o th e mor e face s o n a regula r polyhedra , th e mor e i tapproximate s a spher e an d th e lowe r it s surfac e area/volum eratio . Fo r example , a n icosahedron , cub e an d tetrahedro n us e6.5%, 24.1 % an d 49 % mor e surfac e area , respectivel y t o enclos eth e sam e volum e a s a sphere . However , a s a resul t o f thei rslope d 'walls' , spherica l o r nea r spherica l polyhedr a d o no tgenerall y provid e th e mos t useabl e interio r floo r spac e fo r agive n volume . See :

Rober t Williams , Natura l Structure : Towar d a For m Language ,Eudaemon Press , pp . 54-103 , 1972 .

37. Tha t is , assumin g al l surface s ar e o f equa l therma l resistance .I n practic e structura l difference s i n roofs , wall s an d floor sfacilitat e differen t therma l resistances , favourin g somewha t abuildin g flattene d fro m perfectl y regula r proportion s whe n th eincrease d surfac e are a i s distribute d mostl y i n floo r an d roo fareas . Furthermor e decrease s i n buildin g heigh t reduc e ai rinfiltratio n du e t o bot h win d an d stac k pressures . See :

K.J . Linton , 'Cas e History : Energ y conservation , Par t 3 , Buildin gShape' , Th e Canadia n Architect , Vol . 22 , No . 3 , pp . 44-45 , March ,1977 .

38. V . Olgyay , Desig n Wit h Climate , Princeto n Universit y Press , p .89, 1963 .

39. Th e furthe r exploratio n o f suc h 'therma l similitude ' relationship scoul d lea d t o th e testin g o f inexpensive , scaled-dow n model s o f abuildin g unde r simulate d environments . Tentativel y i t ha s bee nestablishe d tha t th e therma l resistanc e o f a smalle r buildin gmodel b e increase d b y a facto r equa l t o th e squar e roo t o f th escal e reductio n i n orde r t o provid e i t wit h th e sam e therma l tim econstan t o f a large r building .

Kale v Ruberg , Graduat e Student , Sola r Architectur e Group ,Massachusett s Institut e o f Technology , persona l communication ,June , 1978 .

40. V . Olgyay , op . cit. , pp . 53-62 .

On th e othe r hand , a n activ e sola r syste m woul d benefi t fro m th esol-ai r effect s o f a n orientatio n wes t o f south . Thi s woul dimprov e operatin g efficiencie s b y minimizin g collector/ambien ttemperatur e differences .

41. M. Altma n e t al , 'Conservatio n an d Bette r Utilizatio n o f Electri cPower B y Mean s o f Therma l Energ y Storag e an d Sola r Heating' ,NSF/RANN/SE/GI 27976/PR73/5 , Universit y o f Pennsylvania ,Philadelphia , 1973 , als o reproduce d i n th e following :

111

B. Anderson , Th e Sola r Home Book , Harrisville , N.H. , 1976 , p . 174 .

J.F . Kreider , F . Kreith , Sola r Heatin g an d Cooling , Washington ,1977 , p . 67 .

42. Fo r sunpat h chart s o f altitud e an d azimut h angles , see :

C.G. Ramsey , H.R . Sleeper , Architectura l Graphi c Standards , Ne wYork , J . Wile y an d Sons , 1972 .

For table s o f altitud e an d azimut h angle s a t Canadia n Latitudes ,see :

D.G. Stephenson , 'Table s o f Sola r Altitude , Azimuth , Intensit yand Hea t Gai n Factor s fo r Latitude s fro m 4 3 t o 5 5 Degree s North' ,Nationa l Researc h Counci l No . 9528 , Ottawa , 1967 , pp . 11-24 .

43. E.A . Arens , P.B . Williams , 'Th e Effec t o f Win d o n Energ yConsumptio n i n Buildings' , Energ y an d Buildings , Vol . 1 , p . 78 ,1977 .

44. A.G . Wilson , 'Ai r Leakag e i n Buildings' , Canadia n Buildin g Diges tNo. 23 , Nationa l Researc h Council , Ottawa , 1961 , p . 1 .

45. V . Olgyay , op . cit. , pp . 96-99 .

46. W.A . Dalgleish , D.W. Boyd , 'Win d o n Buildings' , Canadia n Buildin gDigest , No . 28 , Nationa l Researc h Council , Ottawa , pp . 2-3 , 1962 .

47. G.T . Tamura , 'Measuremen t o f Ai r Leakag e Characteristic s o f Hous eEnclosures' , ASHRAE Transactions , Vol . 81 , Par t 1 , p . 204 , 1975 .

48. Perspective s o n Acces s t o Sunlight , Ontari o Ministr y o f Energ yWorkin g Paper , Toronto , May , 1978 7

49. Marshal l Hunt , Davi d Bainbridge , 'Th e Davi s Experience' , Sola rAge, Vol . 3 , No . 5 , pp . 20-23 , May , 1978 .

50. Joh n Carrol , Pa t Chen , Ottaw a Cit y Hal l Plannin g Department ,persona l communication , June , 1978 .

51. Ric k Coker , Municipalit y o f Nepea n Plannin g Office , persona lcommunication , June , 1978 .

52. Atmospheri c Environmen t Service , Environmen t Canada , variou spublication s including : 'Ne w Estimate s o f Averag e Globa l Sola rRadiatio n i n Canada' , Ottawa , 1969 ; 'Monthl y Radiatio n Summary' ,Ottawa , monthly ; 'Monthl y Record' , Ottawa , monthly ; 'Canadia nNormals , 1-SI , Temperature' , Downsview , 1975 .

112

53. "Usin g hou r b y hou r weathe r dat a ove r a yea r i n Syracuse , Ne wYork , a simulatio n i s performe d t o compar e th e therma lperformanc e o f a wel l insulate d 140 0 squar e foo t dwellin gThe (direc t gain ) passiv e syste m wit h shutter s show s considerabl ybette r performanc e tha n th e activ e system , eve n whe n th ecollecto r siz e o f th e latte r approache s twic e tha t o f th epassive" .

W.J. Cole , L.F . Kinney , 'Appropriat e System s fo r Heatin gBuildings : Th e Cas e fo r Passiv e Sola r wit h Movabl e Insulation' ,Proceeding s o f Th e Secon d Nationa l Passiv e Sola r Conference ,March 16-18 , Vol . 3 , pp . 795-799 , Philadelphia , 1978 .

54. J.T . Roger s e t al , 'Th e Equivalen t Degree-Da y Concep t Fo rResidentia l Spac e Heatin g Analysis' , Proceeding s o f Th e Semina rFor Hea t Transfe r i n Buildings , Dubrovnic , Yugoslavia , Augus t 2 9- Septembe r 2 , 1977 .

55. Alastai r Gillespie , Ministe r o f Energy , Mine s an d Resource sCanada, speec h t o th e Canadia n Electrica l Association , Toronto ,June 1977 , a s quote d b y Charle s Caccia , M.P . fo r Davenport , i n'Canadian s An d Th e Sun' , May , 1978 , p . 2 .

56. Pete r Middleton , e t al , Canada' s Renewabl e Energ y Resources . A nAssessmen t o f Potential , Toronto , April , 1976 , p . 31 .

57. S.R . Hastings , R.W. Crenshaw , 'Windo w Desig n Strategie s T oConserv e Energy' , U.S . Governmen t Printin g Office , Washington ,1977 , Chapte r 4 , pp . 1-26 .

58. M.J . Minot , 'Ne w Ant i Reflectio n Integra l Films ' a s reporte d i nSola r Energ y Digest , Vol . 7 , No . 3 , p . 3 , September , 1976 .

The sam e typ e o f anti-reflection , aci d leachin g proces s i sapplie d t o th e glazin g o n th e Honeywell-Lenno x LS C 18- 1 sola rcollector .

59. F.W . Hutchinson , 'Sola r Hous e Analysi s an d Research' , Progressiv eArchitecture , May , 1947 .

60. Ke n Cooper , 'Mea n Monthl y Ne t Hea t Transfe r Throug h Windows' ,Sola r Energ y Updat e '77 , Proceeding s o f th e Annua l Genera lMeetin g an d Conferenc e o f th e Sola r Energ y Societ y o f Canada ,August 22-24 , Edmonton , 1977 .

61. R.R . Gilpin , 'Th e Us e o f Sout h Facin g Window s Fo r Sola r Heatin gi n a Norther n Climate' , Sola r Energ y Updat e '77 , SESCI , Edmonton ,1977 .

62. B.D . Gough , 'Passiv e Sola r Heating : A n Architectura l Coexistenc eWit h Th e Sun , Undergraduat e Thesis , Schoo l o f Architecture ,Carleto n University , pp.64-60 , B4-B5 , April , 1977 .

113

63. R.E . Jones , E.J . Tymura , 'Passiv e Sola r Heatin g Desig n Fo rCanada' , Sola r Energ y Updat e '77 , SESCI , Edmonton , 1977 .

64. G.P . Mitalas , op . cit. , Figure s 2 an d 3 .

65. W.L . Snick , R.A . Jones , 'Th e Illinoi s Lo-Ca l House' , Counci lNotes , Smal l Homes Buildin g Researc h Council , Universit y o fIllinoi s a t Urban a - Champaign , Vol . 1 , No . 4 , March , 1976 . Fo reconomi c aspects , se e also :

Sharin g th e Sun , Sola r Technolog y i n th e Seventies , Winnipeg ,1976 , Vol . 4 , pp . 30-35 .

66. Ed . Mazri a e t al , 'A n Analytica l Mode l Fo r Passiv e Sola r Heate dBuildings' , A Sola r Worl d an d a Sola r Market , Proceeding s o f th e1977 Annua l Meetin g o f th e America n Sectio n o f th e Internationa lSola r Energ y Society , Orlando , Jun e 1977 , Sec . 11 , pp . 10-14 .

67. E . Dean , A.H . Rosenfeld , 'Modelin g Natura l Energ y Flo w i nHouses' , Energ y an d Buildings , Vol . 1 , pp . 19-26 , 1977 .

68. Ralp h M. Lebens , ' A Desig n Too l T o Asses s Roo m Ai r Temperature sof a Passivel y Heate d Space' , Th e Proceeding s o f th e Secon dNationa l Passiv e Sola r Conference' , Marc h 16-18 , Vol . 2~ j pp .549-554 , Philadelphia , 1978 .

69. J.D . Balcom b e t al , 'Rule s o f Thumb' , a s reporte d b y R.P .Stromberg , S.O . Woodal l i n Passiv e Sola r Buildings ; A Compilatio nof Dat a an d Results , Sandi a Laboratories , Albequerque , 1977 .

70. C.W. Griffin , Energ y Conservatio n i n Buildings : Technique s Fo rEconomica l Design , Th e Constructio n Specification s Institute ,Washington , 1975 .

71. A.R . Ostrom , ' A Guid e t o Lif e Cycl e Costin g o f Energ y Systems ,wit h Specia l Referenc e t o Spac e an d Wate r Heating' , Workin g Pape rfo r Renewabl e Energ y Resourc e Branch , Energy , Mine s an d Resource sCanada, Ottawa , March , 1978 .

72. Associat e Committe e On Th e Nationa l Buildin g Code . Draf t o fCanadia n Cod e Fo r Energ y Conservatio n i n Ne w Buildings , Nationa lResearc h Council , Ottawa , June , 1977 .

73- Ke n Cooper , 'Energ y Conservin g Homes ' SOL 10 , Newslette r o f th eSola r Energ y Societ y o f Canada , pp . 2-3 , October , 1977 .

74. Comments b y th e Offic e o f Energ y Conservation , Energy , Mine s an dResources , Canad a t o th e Associat e Committe e o n th e Nationa lBuildin g Cod e recommendin g therma l standard s fo r th e buildin genvelop e an d combustio n heatin g syste m highe r tha n thes e se tfort h i n th e draf t o f Canadia n Cod e Fo r Energ y Conservatio n i nNew Buildings :

114

Ia n Efford , Charli e Ficner , 'Comment s o n Propose d Energ yStandard' , Appendice s A , B an d C , 3 0 Sept. , 1977 , als oCorrection s t o Appendi x B , 1 7 Oct. , 1977 .

75. D.A . Robinson , 'Insulatin g a Sola r House' , Proceeding s o f th e1978 Annua l Meetin g o f th e America n Sectio n o f th e Internationa lSola r Energ y Society , Inc. , Vol . 2.2 , pp . 196-201 , Denver , 1978 .

76. B.D . Gough , op . cit. , pp . 52-63 .

77. America n Societ y o f Heating , Refrigerating , Ventillatin g an d Ai rConditioning , Engineers , 'Handboo k o f Fundamentals' , Ch . 20 ,ASHRAE, Ne w York , 1972 .

78. J.T . Roger s e t al , op . cit, , p . 3 .

79. D.G . Stephenson , 'Determinin g Th e Optimu m Therma l Resistanc e Fo rWall s an d Roofs , Buildin g Researc h Not e No . 105 , p . 4 , Nationa lResearc h Council , Ottawa , 1976 .

80. Masonar y Industr y Committee , 'Mass , Masonary , Energy' , prepare dby Hankin s an d Anderso n Inc. , Richmond , Va. , 1976 .

81. TRNSYS, ' A Transien t Simulatio n Problem' , Engineerin g Experimen tStatio n Repor t No . 38 . Sola r Energ y Laboratory , Universit y o fWisconsin , Madison , 1975 .

82. J.F . Orgill , K.G.T . Hollands , 'WATSUN - Sola r Heatin g Simulatio nand Economi c Evaluatio n Program ' Universit y o f Waterlo o Researc hInstitute , Waterloo , 1976 .

83. ASHRAE, op . cit. , pp . 410-416 .

84. Se e many paper s i n 'Passiv e Sola r Stat e o f th e Art' , Proceeding sof th e 2n d Nationa l Passiv e Sola r Conference , Vol . II ,'Simulation' , pp . 349-40 9 an d pp . 529-580 , Philadelphia , 1978 .

85. A detaile d therma l load s progra m calle d ENCORE-CANADA ha s bee ndevelope d a t th e Divisio n o f Buildin g Researc h o f th e Nationa lResearc h Council , Ottawa . I t wa s develope d specificall y fo rsimulatin g smalle r residentia l building s an d i s exhaustiv e i nmodellin g bot h win d an d stac k pressure d ai r infiltration , base -ment hea t losses , therma l capacitanc e effect s i n multi-layere dwal l an d roo f assemblie s an d th e operatio n o f fuel-fire d furnaces .Whil e i t calculate s direc t passiv e sola r gain s throug h glazing ,i t wa s no t develope d specificall y t o simulat e passiv e sola rheate d buildings . I t i s no t sensitiv e t o variation s i n th equantit y an d distributio n o f capacitanc e material s withi n th ebuildin g interio r no r i s i t applicabl e t o an y indirec t passiv esystem . See :

115

A. Konrad , B.T . Larsen , 'Encore-Canada : Compute r Progra m Fo r Th eStud y o f Energ y Consumptio n o f Residentia l Building s i n Canada' ,Proceeding s o f th e Thir d Internationa l Symposiu m o n th e Us e o fComputer s fo r Environmenta l Engineerin g Relate d t o Buildings ,Banff , May , 1978 .

Als o th e Ontari o Ministr y o f Energ y ha s commissione d Joh n Hix ,Architec t i n collaboratio n wit h Mechanica l Engineer s Okins ,Leipciger , Cuplinskas , Kaminker , Associate s i n a stud y whic hinclude s th e developmen t o f passiv e sola r performanc e simulatio nmethod s an d formulae .

86. K.T . Kusuda , 'NBSLD , th e Compute r Progra m fo r Heatin g an d Coolin gLoads i n Buildings' , U.S.D.I. , NBS Buildin g Scienc e Serie s 69 ,July , 1976 .

87. J.D . Balcom b e t al , 'Simulatio n Analysi s o f Passiv e Sola rBuilding s - Compariso n wit h Tes t Roo m Results' , Proceeding s o fth e 197 7 Annua l Meeting , America n Section , ISES , Volum e 1 ,Sectio n 11 , pp . 5-9 , Orlando , 1977 .

88. However , 'th e Nationa l Burea u o f Standard s ha s undertake n aprojec t t o prepar e a referenc e documen t tha t wil l provid e fo r th esystemati c classification , consisten t instrumentation , evaluatio nand reportin g o f th e therma l performanc e o f passiv e component ssystem s an d buildings' . See :

W. Ducas , J . Holton , W. Angel , E . Streed , 'Therma l Dat aRequirement s an d Performanc e Evaluatio n Procedure s fo r Passiv eBuildings' , Proceeding s o f th e 2n d Nationa l Passiv e Sola rConference , Vol . II , pp . 411-430 , Philadelphia , 1978 .

89. C.H . Richards , ' A Passiv e Sola r Simulatio n Fo r Genera l Use' ,Proceeding s o f th e 2n d Nationa l Passiv e Sola r Conference , Vol .II , pp . 349-352 , Philadelphia , 1978 .

90. B.Y.H . Liu , R.C . Jordan , 'Th e Interrelationshi p an dCharacteristi c Distributio n o f Direct , Diffus e an d Tota lRadiation' , Sola r Energy , Vol . 4 , No . 3 , July , 1960 .

91. D.W. Ruth , R.E . Chant , 'Th e Relationshi p o f Diffus e Radiatio n t oTota l Radiatio n i n Canada' , Sola r Energy , Vol . 18 , pp . 153-154 ,1976 .

92. J.F . Orgill , K.G.T . Hollands , 'Correlatio n Equatio n fo r Hourl yDiffus e Radiatio n o n a Horizonta l Surface' , Determinin g th eTechnica l an d Economi c Feasibilit y o f Sola r Energ y Heatin g i nCanada, Appendi x B , April , 1976 .

93. R.C . Temps , K.L . Coulson , 'Sola r Radiatio n Inciden t Upo n Slope sof Differen t Orientations' , Sola r Energy , Vol . 19 , pp . 179-184 ,1977 .

116

94. J.F . Orgill , K.G.T . Hollands , op . cit. , pp . 17-18 .

95. J.E . Hay , ' A Revise d Metho d fo r Determinin g th e Direc t an dDiffus e Component s o f th e Tota l Short-Wav e Radiation' ,Atmosphere , Vol . 14 , No . 4 , 1976 .

96. J.E . Hay , 'Shortwav e Radiatio n o n Incline d Surfaces' . Repor t t oAtmospheri c Environmen t Service , Toronto , Contrac t No . DSS05576-02095 , August , 1977 .

97. 'Reques t fo r Gran t Applicatio n - RFGA - 8600 : Passiv e Sola rResidentia l Desig n Competitio n an d Demonstration' , Sec . E , pp .8-17 , Departmen t o f Housin g an d Urba n Development , Washington ,May, 1978 .

98. S.A . Klei n e t al , ' A Desig n Procedur e Fo r Sola r Heatin g Systems' ,Sola r Energy , Vol . 18 , pp . 113-127 , 1976 .

99. Ed . Mazria , 'Th e Passiv e Sola r Energ y Book ' t o b e publishe d b yth e Rodal e Press , Emmaus, P.A . i n Septembe r 1978 , se e also :

Ed. Mazria , ' A Desig n Sizin g Procedur e Fo r Direc t Gain , Therma lStorag e Wall , Attache d Greenhous e an d Roo f Pon d Systems' ,Proceeding s o f th e 2n d Nationa l Passiv e Sola r Conference , Vol . 2 ,pp. 390-392 , Philadelphia , 1978 .

100. S.R . Hastings , R.W. Crenshaw , op . cit. , Sec . 4 , p . 2 .

101. K.G.T . Hollands , G.D . Raithby , T.E . Unny , 'Studie s o n Method s o fReducin g Hea t Losse s Fro m Fla t Plat e Sola r Collectors' ,Universit y o f Waterlo o Researc h Institute , Waterloo , 1975 .

102. Dou g Hart , 'Th e Honeycom b Hea t Trap : It s Applicatio n i n Fla tPlat e Sola r Collectors' , Proceeding s o f th e 4t h Annua l Conferenc eof th e Sola r Energ y Societ y o f Canad a Inc. , Vol . 2 , Sec . 1-1-7 ,London , 1978 .

103. Mari a Telkes , 'Tromb e Wal l Wit h Phas e Chang e Storag e Material' ,Proceeding s o f th e 2n d Nationa l Passiv e Sola r Conference , Vol .II , pp . 283-287 , Philadelphia , 1978 .

104. R.M . Winegarner , 'Hea t Mirro r - A Practica l Alternativ e T o Th eSelectiv e Surface, ' Sharin g theSun! , Proceeding s o f th e Join tConferenc e o f ASISE S an d SESCI , Vol . 6 , pp . 339-348 , Winnipeg ,1976 .

105. Stephe n Selkowitz , 'Transparen t Hea t Mirror s fo r Passiv e Sola rHeatin g Applications' , Proceeding s o f th e 2n d Nationa l Passiv eSola r Conference , Vol . 2 , pp . 329-334 , Philadelphia , 1978 .

106. anon . Th e Experimenta l House , Phillip s Researc h Laboratory , pp .8, 13 , 14 , Aachen , 1976 .

117

107. Sea n Wellesley-Miller , 'Weathe r Responsiv e Buildin g Skins ;Concept s an d Configurations' , Proceeding s o f th e 2n d Nationa lPassiv e Sola r Conference , Vol . 2 , pp . 493--500 , Philadelphia , 1978 .

108. anon . 'Fla t Glas s Product s fo r Sola r Energ y Applications' ,Technica l Bulleti n ASG 01.200 , ASG Industrie s Inc. , Kingsport ,Tennessee , 1977 .

The sam e manufacture r produce s a pebbl e finish , .01 % iro n oxid econten t tempere d glas s o f eve n highe r sola r transmissivit y calle d'Sunadex' . A 5 mm shee t transmit s 91.3 % o f sola r radiatio n a tnormal incidence .

109. R.B . Pettit , 'Sola r Average d Transmittanc e Propertie s o f Variou sGlazings' , Proceeding s o f th e 197 8 Annua l Meetin g o f th e America nSectio n o f th e Internationa l Sola r Energ y Society , Inc. , Vol .2.2 , pp . 294-299 , Denver , 1978 .

110. Da y Chahroudi , 'Variabl e Transmissio n Sola r Membrane' ,Proceeding s o f th e 2n d Nationa l Passiv e Sola r Conference , Vol . 2 ,pp. 343-347 , Philadelphia , 1978 .

111. Roll-u p insulatin g shades :

John Schnebly , T . Lowell , M. Ross , 'Th e Windo w Quilt * Insulatin gShade' , Proceeding s o f th e 2n d Nationa l Passiv e Sola r Conference ,Vol . 2 , pp . 314-316 , Philadelphia , 1976 .

*Manufacture d b y Appropriat e Technolog y Corporation , Brattleboro ,Vermont .

112. A multilaye r roll-u p therma l shad e whic h conform s tigh t whe nrolle d u p ye t expand s int o 4 dea d ai r space s whe n rolle d down .Independentl y teste d a t R 1 5 FT 2 o F HR/BTU .

anon . 'I S Hig h "R " Shade' , Technica l Pape r b y Insulatin g Shad eCompany, 1 7 Wate r St. , Guilford , Conn . 06437 .

113. Freo n actuate d 'Skylid 1; cli p o n 'Nightwall' ; styrofoa m bead sblow n i n glazin g ai r spac e 'Beadwall' . See :

Rober t Hymer , 'Movabl e Insulation : Ne w Development s a tZomeworks' , Proceeding s o f th e 2n d Nationa l Passiv e Sola rConference , Vol . 2 , pp . 310-313 , Philadelphia , 1978 .

114. Sit e fabricate d exterio r awnin g an d slidin g pocke t shutters . See :

E.H. Grolle , P.J . Catania , 'Th e Saskatchewa n Energ y Conservatio nHouse' , Sola r Energ y Updat e '77 , p . 4 , SESCI , Edmonton , 1977 .

115. Researc h an d Developmen t Bulletin , Departmen t o f Suppl y an dServices , Canada , No . 56 , p.5. , Nov . 1977 .

118

116. Da y Charoudi , 'Building s a s Organisms' , Proceeding s o f th e 2n dNationa l Passiv e Sola r Conference , pp . 276-282 , Philadelphia ,

117. Sea n Wellesley-Miller , op . cit. , p . 498 .

118. T.E . Johnson , 'Preliminar y Performanc e o f th e M.I.T . Sola rBuildin g 5' , Proceeding s o f th e 2n d Nationa l Passiv e Sola rConference , pp . 610-616 , Philadelphia , 1978 .

119. R.S . Dumont e t al , 'A n Ai r t o Ai r Hea t Exchange r fo r Residences' ,Departmen t o f Mechanica l Engineering , Universit y o f Saskatchewan ,Saskatoon , 1978 .

120. S . Mastoris , 'Efficienc y o f Electri c Wate r Heaters' , Ontari oHydr o Researc h Divisio n Repor t No . 76-128-K , Toronto , 1976 .

121. Associat e Committe e o n th e Nationa l Buildin g Code , Measure s Fo rEnerg y Conservatio n i n Ne w Building s 1978 , NRCC No . 16574 ,Nationa l Researc h Counci l o f Canada , Ottawa , 1978 .

122. Davi d Claridge , 'Windo w Management an d Energ y Savings' , Efficien tUse o f Energ y i n Buildings , LB L 4411 , Lawrenc e Berkle yLaboratories , p . 57 , Berkley , CA, 1976 .

123. mean temperatur e o f material s 25-3O°F .

ASHRAE Handboo k o f Fundamental s 1967 , Desig n Hea t Transmissio nCoefficients , Ch . 26 , pp . 429-434 , America n Societ y o f Heating ,Refrigeratin g an d Air-Conditionin g Engineers , Ne w York , 1967 .

124. marke t pric e o f materia l only , bul k orde r b y contractor , fro m

Lansdowne' s Constructio n Cos t Handbook , 1978 , p . 245 , Davi d K .Lansdown e an d Partner s Ltd. , London , Ontario , 1978 .

125. no n discounte d retai l price , smal l orde r o f hig h qualit y doubl eand tripl e glazin g wit h woo d fram e an d sas h fro m a telephon esurve y o f retailer s i n th e Ottaw a area , May , 1978 .

126. anon . Detaile d Energ y Suppl y an d Demand i n Canada , 1975 ,Statistic s Canada , Catalogu e 57-207 , pp . 26 , 27 , Ottawa , Sept. ,1977 .

127. anon. , Energ y Conservatio n i n Canada ; Program s an d Perspectives ,Energy , Mine s an d Resource s Canada , Repor t E P 77-7 , p . 17 ,Ottawa , 1977 .

128. anon. , Electri c Powe r i n Canad a 1975 , Energy , Mine s an d Resource sCanada, p . 39 , Ottawa , 1976 .

119

129. Canadia n Housin g Statistics , Centra l Mortgag e an d Housin gCorporation , p.72 , Ottawa , March , 1976 .

130. Residentia l Standard s 1970 , Associat e Committe e o n th e Nationa lBuildin g Code , pp.83-86 . Nationa l Researc h Counci l o f Canada ,Ottawa , November , 1972 .

131. Residentia l Standard s 1975 , Associat e Committe e o n th e Nationa lBuildin g Code , pp.80-83 , Nationa l Researc h Counci l o f Canada ,Ottawa , 1975 .

132. Some o f thes e program s hav e bee n submitte d t o an d ar e no wdistribute d b y Hewlet t Packar d Ltd . see :

'Hourl y Insolatio n an d Transmission' , prgm . no . 0153 1 D , 1 4 pages ,August , 1977 ; 'Dail y Insolation' , prgm . no . 0162 9 D , 1 5 pages ,Nov. , 1977 ; 'Heliodon' , prgm . no . 01759D , 9 pages , Nov . 1977 ,HP-67/9 7 User' s Librar y o f Contribute d Programs , Hewlet t Packar dLtd. , Corvallis , Oregon , Addend a No . 2 an d 3 , Apr. , Nov. , 1978 .

133. J.A . Duffie , W.A . Beckman , Sola r Energ y Therma l Processes ,pp.14-18 , Joh n Wile y an d Sons , Ne w York , 1975 .

134. A . Whillier , 'Desig n Factor s Influencin g Sola r Collecto rPerformance' , Lo w Temperatur e Engineerin g Application s o f Sola rEnergy , pp . 27-28 , America n Societ y o f Heatin g Refrigeratin g an dAi r Conditionin g Engineers , Ne w York , 1967 .

135. G.P . Williams , L.W . Gold , 'Groun d Temperatures' , Canadia nBuildin g Diges t No . 180 , D.B.R. , N.R.C.C. , Ottawa , July , 1976 .

136. ASHRAE, op . cit . p.410 .

137. S.A . Klein , 'Calculatio n o f Monthl y Averag e Insolatio n o n Tilte dSurfaces' , Sola r Energy , Vol . 19 , pp . 325-329 .Permagon Press , 1977 .