heat load (pdf)

8/12/2019 Heat Load (PDF)

1/107

Basics of PsychrometricsBasics of Psychrometrics

Practical Heat Load CalculationPractical Heat Load Calculation

Duct Design fundamentalsDuct Design fundamentals

ISHRAE TRAININ PR!RA"ISHRAE TRAININ PR!RA"

Created #y Ra$ee% &a''ar ( A)ril *++,Created #y Ra$ee% &a''ar ( A)ril *++,

Presented By Prashant DesaiPresented By Prashant Desai


2/107

22

Sensi#le HeatSensi#le Heat

Sensible heat isSensible heat is dry heatdry heatcausing change incausing change in

temperature but not in thetemperature but not in the

moisture content.moisture content.

Btu/Hr = 1.08 x cfm x deltaBtu/Hr = 1.08 x cfm x delta

tt


3/107

33

Latent HeatLatent Heat

Latent heat is the heat thatLatent heat is the heat thathen supplied to! or remo"edhen supplied to! or remo"ed

from air! there is a change infrom air! there is a change in

the moisture content of the air!the moisture content of the air!but the temperature of the airbut the temperature of the air

is not changed.is not changed.

Btu/Hr = cfm x 0.#8 x delta $Btu/Hr = cfm x 0.#8 x delta $


4/107

44

Enthal)yEnthal)y

%nthalpy is the thermodynamic%nthalpy is the thermodynamicterm for the heat content of air.term for the heat content of air.

Since air can gain heat ith eitherSince air can gain heat ith either

an increase in temperature oran increase in temperature ormoisture content! the termsmoisture content! the terms

sensible heat and latent heat aresensible heat and latent heat are

used to distinguish ho air hasused to distinguish ho air has

gained heat.gained heat.


5/107

55

Heat TransferHeat Transfer


6/107

66

ConductionConduction

&onduction of heat is the process of heat&onduction of heat is the process of heattransfer in solids.transfer in solids. 'n buildings! heat is transferred by conduction!'n buildings! heat is transferred by conduction!

mainly by the alls or roof either inards ormainly by the alls or roof either inards oroutards. &onduction (o rate through a all ofoutards. &onduction (o rate through a all ofa gi"en area can be described by the e)uation *a gi"en area can be described by the e)uation *

++SS= , - - = , - -

herehere+ = conduction heat (o rate! in Btu/Hr+ = conduction heat (o rate! in Btu/Hr, = surface area! in s)uare feet, = surface area! in s)uare feet = &onducti"ity "alue in $atts/s).ft deg = &onducti"ity "alue in $atts/s).ft deg

= temperature di2erence in deg = temperature di2erence in deg


7/107

77

Con%ectionCon%ection

&on"ection is the process of transfer of heat in&on"ection is the process of transfer of heat inhich molecules of cool air absorb heat from ahich molecules of cool air absorb heat from aarm surface air! rise! and carry it aay.arm surface air! rise! and carry it aay.

&on"ection heat (o in a building occurs&on"ection heat (o in a building occursmainly in the interior spaces 3 ithin a room!mainly in the interior spaces 3 ithin a room!beteen a gap an air gap in the alls! or roofbeteen a gap an air gap in the alls! or roof

or ithin to layers of glass in a indo.or ithin to layers of glass in a indo.&on"ection and in4ltration are both forms of&on"ection and in4ltration are both forms of

mass (o but con"ection heat (o ta5es placemass (o but con"ection heat (o ta5es placemainly in the interiors hile in4ltration ta5esmainly in the interiors hile in4ltration ta5esplace beteen the building and the outside air.place beteen the building and the outside air.


8/107

88

Con%ection heatCon%ection heat

Btu/Hr = cfm x 1.08Btu/Hr = cfm x 1.08x delta tx delta t

Btu/Hr = cfm x 0.#8Btu/Hr = cfm x 0.#8

x delta $.x delta $.


9/107

99

RadiationRadiation

6adiation is the process of heat6adiation is the process of heat(o in electromagnetic a"es from(o in electromagnetic a"es froma hotter surface to empty space.a hotter surface to empty space.

he radiation balance 7fa"ors7 thehe radiation balance 7fa"ors7 the

cold surface.cold surface.his is the only method of heathis is the only method of heattransfer hich does not re)uire atransfer hich does not re)uire amedium for heat transfermedium for heat transfer


10/107

1010

RadiationRadiation

6adiation heat gain in the buildings6adiation heat gain in the buildingsis considered mainly through theis considered mainly through the

indo.indo.

++rr= , - Sc - Sg= , - Sc - Sg

Sg = solar gain factor of indoSg = solar gain factor of indoglass.glass.

Sc = Solar heat gain of fenestration/Sc = Solar heat gain of fenestration/

Solar heat gain of double strengthSolar heat gain of double strength

glassglass


11/107

1111

Calculating - %alueCalculating - %alue

utside air 4lmutside air 4lmransmission thruransmission thru

the material layersthe material layers,ir space.,ir space.

'nside air 4lm'nside air 4lm


12/107

1212

TransmissionTransmission

Heat (os from a higher temperatureHeat (os from a higher temperatureto a loer temperature.to a loer temperature.

heat transmission per hour*heat transmission per hour*H = , - - H = , - -

is the o"erall heat transmission is the o"erall heat transmissioncoe9cient expressed incoe9cient expressed inB/Hr/S).ft/:eg temperatureB/Hr/S).ft/:eg temperaturedi2erence.di2erence.

he product , x is also calledhe product , x is also called

7conductance7.7conductance7.


13/107

1313

Thermal Conducti%ity of aThermal Conducti%ity of a

material( 'material( '

is the heat transmitted through theis the heat transmitted through thematerial expressed as B/Hr/S).ft/'nchmaterial expressed as B/Hr/S).ft/'nch

thic5ness/:eg temperature di2erence.thic5ness/:eg temperature di2erence.'f 5 is the conducti"ity of the material'f 5 is the conducti"ity of the material

then 1/5 is the resistance 76; of thethen 1/5 is the resistance 76; of thematerial of 1 s).ft cross section and 17material of 1 s).ft cross section and 17

thic5ness.thic5ness.'f the thic5ness is 7t7 inches! the'f the thic5ness is 7t7 inches! the

resistance becomes


14/107

1414


material( &material( &

'n electrical analogy! resistances'n electrical analogy! resistancesconnected in series are added toconnected in series are added to

4nd the total resistance.4nd the total resistance.Similarly! if a barrier is made up ofSimilarly! if a barrier is made up of

se"eral materials! the indi"idualse"eral materials! the indi"idual

resistances of the componentsresistances of the components

ha"e to be added to arri"e at theha"e to be added to arri"e at the

total barrier resistance.total barrier resistance.


15/107

1515


material( &material( &

'f a barrier is made up of! say! three'f a barrier is made up of! say! threematerials ha"ing thermalmaterials ha"ing thermal

conducti"ities 51! 5> and 5?! the totalconducti"ities 51! 5> and 5?! the total

thermal resistance of the barrier is*thermal resistance of the barrier is*

t1/51 @ t>/5> @ t?/5?t1/51 @ t>/5> @ t?/5?

$here t1! t>! t? are the thic5ness of$here t1! t>! t? are the thic5ness of

the barriers.the barriers.


16/107

1616

- .alue- .alue


17/107


18/107

1818

/ilm Coe0cient/ilm Coe0cient

Li5e thermal conducti"ity! the heatLi5e thermal conducti"ity! the heattransmission capacity of a 4lm istransmission capacity of a 4lm is

expressed as the rate of heatexpressed as the rate of heat

transfer in Btu/Hr/S).ft/deg transfer in Btu/Hr/S).ft/deg

temperature di2erence.temperature di2erence.


19/107

1919

/ilm Coe0cient/ilm Coe0cient

this is called the 4lm coe9cient and isthis is called the 4lm coe9cient and isexpressed by this symbol 7f7. theexpressed by this symbol 7f7. the

reciprocal of 7f7 is the thermalreciprocal of 7f7 is the thermal

resistance of the 4lm.resistance of the 4lm.

747 denotes the 4lm coe9cient on the747 denotes the 4lm coe9cient on the

interior surfaces of the barrier andinterior surfaces of the barrier and

7fo7 denotes the 4lm coe9cient on the7fo7 denotes the 4lm coe9cient on the

exterior surface of the barrier.exterior surface of the barrier.


20/107


21/107

2121

Thermal conductance of airThermal conductance of air

s)aces)ace

,ir spaces transmit heat by*,ir spaces transmit heat by*6adiation! conduction and6adiation! conduction and

con"ection.con"ection.

Btu/Hr/s).ft/deg Btu/Hr/s).ft/deg sed for air spaces greater thansed for air spaces greater than

C thic5ness! and ha"ing noC thic5ness! and ha"ing no

re(ecti"e insulation such asre(ecti"e insulation such as

aluminum foil.aluminum foil.


22/107

2222

- .alue- .alue

6efer the 4gure shoing the6efer the 4gure shoing thecross3section of a barrier ha"ing threecross3section of a barrier ha"ing three

materials of thic5nesses t1! t>! t?!materials of thic5nesses t1! t>! t?!

thermal conducti"ities 51!5>! and 5? andthermal conducti"ities 51!5>! and 5? and

surface conductance @ t?/5? @ 1/fo1/4 @ t1/51 @ t>/5> @ t?/5? @ 1/fo


23/107


24/107

2424

- .alue- .alue

'f 77 is the o"erall heat transmission of'f 77 is the o"erall heat transmission ofthe barrier in B/Hr/S).ft/deg then!the barrier in B/Hr/S).ft/deg then!

1/ is the o"erall thermal resistance of1/ is the o"erall thermal resistance of

the barrier.the barrier.

1/ = 1/f1 @ t1/51 @ t>/5> @ t?/5? @ 1/fo1/ = 1/f1 @ t1/51 @ t>/5> @ t?/5? @ 1/fo

herefore!herefore!

= 1 / 1/f1 @ t1/51 @ t>/5> @ t?/5? @ 1/fo = 1 / 1/f1 @ t1/51 @ t>/5> @ t?/5? @ 1/fo


25/107

2525

Thermal conductance of airThermal conductance of air

s)ace1s)ace1

:ead space of air as a layer:ead space of air as a layer%xceeds C thic5ness%xceeds C thic5nessAo re(ecti"e insulation surfacesAo re(ecti"e insulation surfaces

li5e aluminum foilli5e aluminum foilransmits heat by radiation!ransmits heat by radiation!

con"ection and conduction.con"ection and conduction.

Dalue = 1.1Dalue = 1.1


26/107

2626

- .alue 2*3- .alue 2*3

$ithout dead air space$ithout dead air space = 1 / 1/f1 @ t1/51 @ = 1 / 1/f1 @ t1/51 @

t>/5> @ t?/5? @ 1/fot>/5> @ t?/5? @ 1/fo$ith dead air space$ith dead air space = 1 / 1/f1 @ t1/51 @ = 1 / 1/f1 @ t1/51 @

t>/5> @ t?/5? @ 1/fot>/5> @ t?/5? @ 1/fo @1/a@1/a


27/107

2727

Calculate - %alueCalculate - %alue

8C bric5 all ith EC cement plaster8C bric5 all ith EC cement plasterboth sides.both sides.

,s abo"e! but ith a 1C air gap also.,s abo"e! but ith a 1C air gap also.

,s abo"e! but ith 1C expanded,s abo"e! but ith 1C expanded

polystyrene also.polystyrene also. #C 6&&! ith EC plaster both sides#C 6&&! ith EC plaster both sides

F mm glassF mm glass

GC 6&&! EC plaster both sides! and >CGC 6&&! EC plaster both sides! and >C

thermocole insulation.thermocole insulation.


28/107

2828

Con%ersionCon%ersion

o con"ert "alues*o con"ert "alues*

< ultiply 1 btu/hr.sft.< ultiply 1 btu/hr.sft.#??K8 to getF.#J8>#??K8 to get

$/s)m.


29/107

2929

Heat Load CalculationHeat Load Calculation


30/107

3030

E *+ "ethodE *+ "ethod

'n 'ndia! the % >0 method has become the'n 'ndia! the % >0 method has become thedefacto standard! and is a time pro"en method.defacto standard! and is a time pro"en method.hat e mean is that! if you calculatehat e mean is that! if you calculateinstantaneous loads using this method! then! ininstantaneous loads using this method! then! inmost cases! it ill be reasonably accurate tomost cases! it ill be reasonably accurate toselect correctly siMed e)uipment.select correctly siMed e)uipment.

he % >0 method is a method de"eloped byhe % >0 method is a method de"eloped by&arrier.&arrier.

any more methods ha"e been de"eloped!any more methods ha"e been de"eloped!including a 7heat balance method7! here youincluding a 7heat balance method7! here you

can calculate hourly loads! not Nust thecan calculate hourly loads! not Nust theinstantaneous load at G I.instantaneous load at G I.


31/107

3131

Building Sur%eyBuilding Sur%ey

&ollect architects draings for the&ollect architects draings for thebuilding gi"ing all details and dimensionsbuilding gi"ing all details and dimensionsof alls! (oors! indos! etc. 'f suchof alls! (oors! indos! etc. 'f suchdraings are not a"ailable! then sur"eydraings are not a"ailable! then sur"eythe place and get the details.the place and get the details.

Building orientation.Building orientation.

$indos* Location! siMe and orientation!$indos* Location! siMe and orientation!hether externally or internally shaded.hether externally or internally shaded.

..


32/107

3232

Building Sur%eyBuilding Sur%ey

Iartitions* o non3airconditioned spaces! toIartitions* o non3airconditioned spaces! to5itchens! to toilets.5itchens! to toilets.

6oof construction! light roof! sheet roof!6oof construction! light roof! sheet roof!insulation! edium roof


33/107

3333

Thermal 4oningThermal 4oning

$hat you get as a draing! remember! has the$hat you get as a draing! remember! has thespace di"ided as a geometrical space. Oou ouldspace di"ided as a geometrical space. Oou ouldneed to map out the space as a thermal spacePneed to map out the space as a thermal spaceP

$hat e mean by a thermal space! is that! all$hat e mean by a thermal space! is that! allli5e areas! being fed by a single split orli5e areas! being fed by a single split or

pac5aged or air handling system! and thereforepac5aged or air handling system! and thereforeare at the same temperatures! can be clubbedare at the same temperatures! can be clubbedtogether! for the purposes of heat load.together! for the purposes of heat load.

Simply! if there is a ro of 10 cabins! being fedSimply! if there is a ro of 10 cabins! being fedby the same e)uipment! hile geometricallyby the same e)uipment! hile geometricallythere are 10 spaces! you could treat the entirethere are 10 spaces! you could treat the entire10 cabin space as a single thermal space.10 cabin space as a single thermal space.


34/107

3434

Thermal 4oningThermal 4oning

if there is a ro of 10 cabins! being fed byif there is a ro of 10 cabins! being fed bythe same e)uipment! hile geometricallythe same e)uipment! hile geometricallythere are 10 spaces! you could treat thethere are 10 spaces! you could treat theentire 10 cabin space as a single thermalentire 10 cabin space as a single thermalspace.space.

f course! some Mones! li5e the :ata &entref course! some Mones! li5e the :ata &entreor the dining area! ould be treated asor the dining area! ould be treated asseparate thermal Mones! because their insideseparate thermal Mones! because their insidedesign conditions are di2erent for the restdesign conditions are di2erent for the restof the space.of the space.

Qoning is an art! de"eloped by practice.Qoning is an art! de"eloped by practice.


35/107

3535

eometric 4oneseometric 4ones


36/107

3636

Thermal 4onesThermal 4ones


37/107

3737

"ulti5story #uildings"ulti5story #uildings

Oou could treat a multi3storied building as one single thermalOou could treat a multi3storied building as one single thermal

Mone. 'n hich case e call that a bloc5 load. you do Nust oneMone. 'n hich case e call that a bloc5 load. you do Nust oneheat load calculation! to get the bloc5 load. f course! forheat load calculation! to get the bloc5 load. f course! forpurposes of air distribution! and e)uipment selection! youpurposes of air distribution! and e)uipment selection! youmay need to do a load for each Mone


38/107

3838

H%acindia o0ceH%acindia o0ce


39/107

3939

The Heat Load /ormThe Heat Load /orm


40/107

4040

Pro6lePro6le


41/107

4141

Room Si7eRoom Si7e


42/107

4242

!utside Design Conditions!utside Design Conditions

utside :esign :ata*utside :esign :ata*

$hich Station$hich Station $hat is the Latitude$hat is the Latitude $hat is the :aily range$hat is the :aily range

Summer! onsoon! $interSummer! onsoon! $inter

Ri"en! :B temp. and $B temp.Ri"en! :B temp. and $B temp. ind Rrains from the psychrometric chart.ind Rrains from the psychrometric chart.

Iage 1 and >Iage 1 and >


43/107

4343

!utside Design Conditions!utside Design Conditions

he data e are using is data hichhe data e are using is data hichhas been published a long time ago!has been published a long time ago!

in the DL,S Handboo5. 'ts originin the DL,S Handboo5. 'ts origin

and basis is not 5non.and basis is not 5non.

&urrently! one should use the 'SH6,%&urrently! one should use the 'SH6,%

'nside :esign &onditions :ata.'nside :esign &onditions :ata.


44/107


45/107

4545

Inside Design ConditionsInside Design Conditions

JF deg :B temperatureJF deg :B temperatureFF 6.H.FF 6.H.

J# deg :B temperatureJ# deg :B temperatureFF 6.H.FF 6.H.

#8 deg to J# deg #8 deg to J# deg

F0 to #0F0 to #0


46/107

4646

ASHRAE Comfort ChartASHRAE Comfort Chart


47/107

4747

Comfort 4oneComfort 4one

ost people FT& and the 6H is

beteen G03#F. his Mone canbeteen G03#F. his Mone can

be shon on thebe shon on the psychrometricpsychrometricchart.! and is 5non as thechart.! and is 5non as the

comfort Monecomfort Mone..


48/107

4848

Inside Design ConditionsInside Design Conditions

,s per ,SH6,%! one ould choose JF deg ,s per ,SH6,%! one ould choose JF deg and F0 6H.and F0 6H.

Aote that ith each degree decrease inAote that ith each degree decrease ininside room temperature the load ouldinside room temperature the load ouldincrease by 10 to 1F.increase by 10 to 1F.

sually! esually! e do notdo notgo belo F0 deg supplygo belo F0 deg supplyair temperature for comfort applications.air temperature for comfort applications.

he usualhe usual guaranteedguaranteedinside conditions ha"einside conditions ha"ea tolerance of @ / 3 > deg ! and the 6elati"ea tolerance of @ / 3 > deg ! and the 6elati"ehumidity has a tolerance of @/3 F 6.H.humidity has a tolerance of @/3 F 6.H.

!utside and Inside!utside and Inside


49/107

4949

!utside and Inside!utside and Inside

ConditionsConditions


50/107

5050

!utside Air )er )erson!utside Air )er )erson

Iage 18. Iage 1K 31K8KIage 18. Iage 1K 31K8K

utside air is pro"ided for oxygen and for maintaining theutside air is pro"ided for oxygen and for maintaining thearea under slight positi"e pressure. 'n some applications!area under slight positi"e pressure. 'n some applications!100 outside air is re)uired.100 outside air is re)uired.

cfm / person or air changes per hour! hich e"er is higher.cfm / person or air changes per hour! hich e"er is higher.

sually! 1 air change per hour is used.sually! 1 air change per hour is used.

:educt the amount of in4ltration directly entering into:educt the amount of in4ltration directly entering intothe room. ,dd the amount of exhaust! if any! to get thethe room. ,dd the amount of exhaust! if any! to get thenet outside air to use in the heat load.net outside air to use in the heat load.

&alculation of air changes! is based on the "olume of&alculation of air changes! is based on the "olume ofconditioned space. that means! that the height to be usedconditioned space. that means! that the height to be used

should be the false ceiling! if there is one.should be the false ceiling! if there is one.


51/107

5151

!utside Air!utside Air


52/107

5252

9 Sources of Sensi#le Loads9 Sources of Sensi#le Loads

Heat (o from solar radiation


53/107

5353

Sensi#le ainsSensi#le ains

Solar gainsSolar gainsransmission gainsransmission gainsLights gainsLights gains

%)uipment/ appliances gains%)uipment/ appliances gainsIeople gainsIeople gainsutside air gainsutside air gains

'n4ltration gains'n4ltration gains


54/107

5454

Solar and Transmission ainsSolar and Transmission ains

he suns heat can get into a building inhe suns heat can get into a building inone of to ays 33 through glass andone of to ays 33 through glass and

through alls and roof.through alls and roof.

1.1. Solar gainsSolar gainsthrough glass is absorbedthrough glass is absorbed

instantaneously in the room. his is ininstantaneously in the room. his is inaddition to the conducted heat passed byaddition to the conducted heat passed by

the glass.the glass.

>.>. ransmission gainsransmission gainsthrough glass! alls!through glass! alls!

(oors! ceilings and roofs.(oors! ceilings and roofs.


55/107


56/107

5656

Solar gain e:uationSolar gain e:uation

Solar Rain*Solar Rain*

,rea x Solar Heat Rain x "erall Rlass,rea x Solar Heat Rain x "erall Rlass

actor = Btu/Hractor = Btu/Hr

, x Sg x Sf = ), x Sg x Sf = )

Iage ?! G! F for Solar Heat RainIage ?! G! F for Solar Heat Rain

Iage K for "erall Rlass actorIage K for "erall Rlass actor


57/107

5757

E;ect of orientation and timeE;ect of orientation and time

%2ect of rientation and time on solar gain.%2ect of rientation and time on solar gain.

Rlass facing %ast pea5s in Vuly 3 august at 10 am .Rlass facing %ast pea5s in Vuly 3 august at 10 am .

Rlass facing the South shos the greatest load atRlass facing the South shos the greatest load atnoon! and is loer before and after noon. ,lso! itnoon! and is loer before and after noon. ,lso! itis maximum in :ecember.is maximum in :ecember.

Rlass on the $est is the re"erse of %ast. 't pea5sRlass on the $est is the re"erse of %ast. 't pea5sat G pm! and is max!. in Vuly.at G pm! and is max!. in Vuly.

Rlass on the Aorth and any shaded glass all dayRlass on the Aorth and any shaded glass all daygets some solar heat that is re(ected by dust. fgets some solar heat that is re(ected by dust. fcourse! this is "ery small as compared to directcourse! this is "ery small as compared to directsunlight.sunlight.


58/107

5858

Solar gainSolar gain


59/107

5959

Solar ain /actorSolar ain /actor

Solar gain factor is 1.0 for clear single3panedSolar gain factor is 1.0 for clear single3paned

glass.glass. &an be reduced by*&an be reduced by*


60/107

6060

Insulating gla7ingInsulating gla7ing

&alled ;insulatingC because of an insulating gas or&alled ;insulatingC because of an insulating gas or

"acuum layer."acuum layer.

'nsulated glaMing unit


61/107

6161

Solar ainSolar ain


62/107


63/107

6363

Solar ainsSolar ains


64/107

6464

Transmission gain e:uationsTransmission gain e:uations

,rea x


65/107

6565


66/107

6666

ETD %alue and thermal storageETD %alue and thermal storage


67/107

6767

ETD %alues de)end on>ETD %alues de)end on>

latitudelatitude


68/107

6868

Basis of ETD %aluesBasis of ETD %alues

utside :B at KF deg ! and room at 80 deg .utside :B at KF deg ! and room at 80 deg .

:aily range* >0 deg daily range! and for G0 deg A:aily range* >0 deg daily range! and for G0 deg Alatitudelatitude

Based on >G hour operation.Based on >G hour operation.

:ar53coloured alls.:ar53coloured alls.

Aeeds to be correctedAeeds to be corrected..page J for roofs and correction to %:page J for roofs and correction to %:

Transmission ain Thru ceilingsTransmission ain Thru ceilings


69/107

6969

Transmission ain Thru ceilings(Transmission ain Thru ceilings(

?oors( glass( )artitions1?oors( glass( )artitions1 Aote carefully! hether the area has a (oorAote carefully! hether the area has a (oor

belo ,& or non ,&. Similarly! for the ceilingbelo ,& or non ,&. Similarly! for the ceilingabo"e. Rround (oors could ha"e basements! soabo"e. Rround (oors could ha"e basements! so(oor belo ould be treated as non3,&.(oor belo ould be treated as non3,&.

se a temperature di2erence of F deg f lessse a temperature di2erence of F deg f lessthan the outside :B temperature.than the outside :B temperature.

Sometimes! the (oor belo or ceiling abo"e maySometimes! the (oor belo or ceiling abo"e maybe at di2erent temperature! lets say a loerbe at di2erent temperature! lets say a loertemperature! such as for :ata &entres. hen!temperature! such as for :ata &entres. hen!that needs to be accounted for.


70/107

7070

- .alues- .alues

Iages 1>! 1? 5 "alues.Iages 1>! 1? 5 "alues.

Iage 1G! 5 "alues for insulatingIage 1G! 5 "alues for insulating

materials.materials.

5 = B/Hr/S).ft/'nch5 = B/Hr/S).ft/'nch

thic5ness/:eg thic5ness/:eg

#l R f #l R f


71/107

7171

a#le Roofa#le Roof

Transmission ains @


72/107

7272

Transmission ains


73/107

7373

Transmission ain Thru lassTransmission ain Thru lass

And PartitionAnd Partition,dd all the areas for solar glass! and,dd all the areas for solar glass! and

then add any glass hich is exposed tothen add any glass hich is exposed toa non3airconditioned area.a non3airconditioned area.

or transmission gain thru glass! useor transmission gain thru glass! usethe di2erence beteen the outside andthe di2erence beteen the outside and

the inside design conditions.the inside design conditions.

or transmission gains from partitions!or transmission gains from partitions!use F degree less. Aote! sometimes theuse F degree less. Aote! sometimes thepartition! may be exposed to a hotterpartition! may be exposed to a hotterarea li5e a 5itchen or furnace! in hicharea li5e a 5itchen or furnace! in hichcase! please ta5e care.case! please ta5e care.


74/107

Li htLi ht


75/107

7575

LightsLights

he heat gi"en o2 by lights both incandescenthe heat gi"en o2 by lights both incandescent

and (uorescent


76/107

R t i l iR t i l i


77/107

7777

Return air )lenum gainReturn air )lenum gain


78/107


79/107

7979

Electric "otors( H1P1Electric "otors( H1P1 he heat gi"en o2 by electric motors! machines andhe heat gi"en o2 by electric motors! machines and

appliances is also fairly independent of the roomappliances is also fairly independent of the roomtemperature. 't depends on the actual electricitytemperature. 't depends on the actual electricityused. Aameplate ratings may not re(ect actualused. Aameplate ratings may not re(ect actualloads.loads.

otors many times! are o"er loaded or underotors many times! are o"er loaded or under

loaded. So a usage factor may be used to accountloaded. So a usage factor may be used to accountfor this.for this.

'n addition! the heat from the motor going into the'n addition! the heat from the motor going into theroom! depends on the location of the motor!room! depends on the location of the motor!hether ithin the room or outside the room.hether ithin the room or outside the room.

1 H.I. = >FGF B/Hr.1 H.I. = >FGF B/Hr.

E:ui)ment A))liances gainE:ui)ment A))liances gain


80/107

8080

: ) )) g: ) )) g

e:uatione:uation

FGF = Btu/HrHI x :. x >FGF = Btu/Hr

Iage >GIage >G

Iage >>! >? for heat gain from motors.Iage >>! >? for heat gain from motors.

Peo)lePeo)le


81/107

8181

Peo)lePeo)le

Heat generated by oxidation!Heat generated by oxidation!called metabolic rate.called metabolic rate.

&arried by*&arried by*

6adiation! con"ection


82/107

8282

Peo)le gain e:uationPeo)le gain e:uation

Ieople x SensibleIeople x Sensiblegain/person =gain/person =

Btu/HrBtu/Hr

Iage >1Iage >1

Internal HeatInternal Heat


83/107

8383

Internal HeatInternal Heat

By)ass /actorBy)ass /actor


84/107

8484

By)ass /actorBy)ass /actor

1.1#

# ro = Z #/G# ro = Z #/G

8 ro = Z 8/G8 ro = Z 8/G


85/107

In6ltrationIn6ltration


86/107

8686


'n4ltration page in boo5let.'n4ltration page in boo5let.

'n4ltration is the lea5age of untreated'n4ltration is the lea5age of untreatedoutdoor air through porous alls!outdoor air through porous alls!(oors! roofs! poorly sealed indos!(oors! roofs! poorly sealed indos!etc.etc.

'n4ltration can add a lot of moisture'n4ltration can add a lot of moistureload into the conditioned space.load into the conditioned space.

Renerally! in4ltration is caused by indRenerally! in4ltration is caused by ind"elocity! or stac5 e2ect! or both."elocity! or stac5 e2ect! or both.



87/107

8787


$ind Delocity*$ind Delocity*

he $ind Delocity builds up a pressurehe $ind Delocity builds up a pressureon the indard side of the building!on the indard side of the building!and a slight "acuum on the leeardand a slight "acuum on the leeard

side of the building. his pressureside of the building. his pressuredi2erence causes the air to in4ltrate.di2erence causes the air to in4ltrate.thru cre"ices! poorly gas5eted indosthru cre"ices! poorly gas5eted indosand doors! crac5s! etc.and doors! crac5s! etc.


88/107



89/107

8989


,ir &hange ethod*,ir &hange ethod* to 0.F air changes per to 0.F air changes per

hour.hour.

%2ecti"e Lea5age ,rea ethod.%2ecti"e Lea5age ,rea ethod.

Iages >8! >KIages >8! >K

In6ltration gain e:uationIn6ltration gain e:uation


90/107

9090

In6ltration gain e:uationIn6ltration gain e:uation

'n4ltration air cfm x'n4ltration air cfm xemp.:i2. xemp.:i2. x

1.08=Btu/Hr1.08=Btu/Hr

, cfm x emp.:i2 x, cfm x emp.:i2 x

1.08 = Btu/Hr1.08 = Btu/Hr

By)assed outside air andBy)assed outside air and


91/107

9191

in6ltrationin6ltration

Safeties and Room Sensi#leSafeties and Room Sensi#le


92/107

9292

HeatHeat

* Sources of Latent Loads* Sources of Latent Loads


93/107

9393

* Sources of Latent Loads* Sources of Latent Loads

oisture entering the space from bypassedoisture entering the space from bypassed

outside air and in4ltration.outside air and in4ltration.

oisture through permeation from spaces at aoisture through permeation from spaces at ahigher "apour pressure.higher "apour pressure.

oisture generated ithin the space fromoisture generated ithin the space frommoisture generating obNects. hese obNectsmoisture generating obNects. hese obNectsusually include*usually include*

occu)ants ithin the s)aceoccu)ants ithin the s)ace

moisture generated #y coo'ing or arming a))liancesmoisture generated #y coo'ing or arming a))liances

industrial or )roduction machinery hich e%a)orates aterindustrial or )roduction machinery hich e%a)orates ater


94/107

Latent gains e:uationLatent gains e:uation


95/107

9595

Latent gains e:uationLatent gains e:uation

Ieople x Latent gain/person = Btu/HrIeople x Latent gain/person = Btu/HrIage >1Iage >1

utside air cfm x Rrains x Bypass factorutside air cfm x Rrains x Bypass factorx 0.#8=Btu/Hrx 0.#8=Btu/Hr

'n4ltration air cfm x Rrains x'n4ltration air cfm x Rrains x0.#8=Btu/Hr0.#8=Btu/Hr

Steam lb/Hr x 1080 btu/lb = Btu/HrSteam lb/Hr x 1080 btu/lb = Btu/Hr

Room Latent Heat and Room TotalRoom Latent Heat and Room Total


96/107

9696

HeatHeat

!utside Air Heat and rand!utside Air Heat and rand


97/107

9797

SafetiesSafeties


98/107

A))aratus De PointA))aratus De Point


99/107

9999

A))aratus De PointA))aratus De Point

:epends on 'nside :esign &onditions:epends on 'nside :esign &onditions

%2ecti"e Sensible Heat actor%2ecti"e Sensible Heat actor

F! >#! >JIages >F! >#! >J

Dehumidi6ed AirDehumidi6ed Air


100/107

100100

Dehumidi6ed AirDehumidi6ed Air

emp. 6ise =


101/107

101101

cfmcfm


102/107

Chec' /iguresChec' /igures


103/107

103103

Chec' /iguresChec' /igures

Load issuesLoad issues


104/107

104104

Load issuesLoad issues

:id you consider indo shading[:id you consider indo shading[:id you consider Moning[:id you consider Moning[:id you consider ballast load for:id you consider ballast load for

lights[lights[

:id you consider in4ltration[:id you consider in4ltration[:id you consider insulating the roof[:id you consider insulating the roof[:id you consider any toilet exhaust[:id you consider any toilet exhaust[

++/reshAir++/reshAir


105/107

105105

++/reshAir++/reshAir

or operation theatres and certain industrialor operation theatres and certain industrial

applications! 100 outside air is used. o calculateapplications! 100 outside air is used. o calculatea heat load for 100 outside air! follo thisa heat load for 100 outside air! follo thisprocedure*procedure*

1. &alculate the heat load ith the bypass factor = 01. &alculate the heat load ith the bypass factor = 0

se the dehumidi4ed cfm that you calculate as these the dehumidi4ed cfm that you calculate as thefresh air cfm! ith Bypass actor for an 8 ro coil.fresh air cfm! ith Bypass actor for an 8 ro coil.

he fresh air )uantity and the dehumidi4ed airhe fresh air )uantity and the dehumidi4ed air)uantity ill con"erge.)uantity ill con"erge.

reated resh air.reated resh air.

ReferencesReferences


106/107

106106

ReferencesReferences

&arrier system :esign anual&arrier system :esign anualDoltas handboo5Doltas handboo5'SH6,% HD,& handboo5'SH6,% HD,& handboo5

,SH6,% undamentals! 1K81,SH6,% undamentals! 1K81,rticles on the internet,rticles on the internet'SH6,% boo5let! undamentals'SH6,% boo5let! undamentals

of air3conditioningof air3conditioning


107/107

.h"acindia.co.h"acindia.co

mm

heat load (pdf)

Documents