building energy eff home

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YOUR GUIDE TO

BUILDING AN ENERGYEFFICIENT HOM E


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The energy for life

Energy is essent ial to ou r daily l ives. It heats our h om es, fuels ou r transpo rt and sup plies

ou r electricity.At th e mo m ent, m ost of th e energy we use com es from fossil fuels such as

oi l , gas, coal and peat. Unfortun ately th ere is a l im ited supp ly of fossi l fuels in t he w orld

and we are using them up at a very fast rate.The other downside to fossil fuels is that

burning them for energy also produces CO2, a greenho use gas, w hich causes climate

change. That s w here sustainable energy comes in.

So what is sustainable energy?

Sustainable en ergy refers to a w ay we can u se and gen erate en ergy th at is mo re efficient

and less harmful to t he environm ent. Anot her way of explaining sustainable energy is

th at i t wi l l al low us to m eet our present energy needs w ithou t com prom ising th e abi l i tyof fut ure generations to m eet their ow n n eeds.We can do this by being m ore efficient in

ho w w e use energy in our daily l ives and also by in creasing t he amo un t of energ y that

com es from renew able sou rces such as th e w ind, th e sun , rivers and o ceans.

What are the benef its of sustainable energy?

The go od n ews is th at being sustainable in ho w yo u use energy has im m ediate benefit s:

It w i ll save you money on your e lect r ic ity and heat ing b i ll s

Your home w i ll be more comfortab le and convenien t

And you wi ll also be making a v ita l cont r ibut ion to reduc ing c limate change

Believe it or no t, th e sm all actions you t ake to be m ore energy eff icient in your ho m e can

have a very signif icant im pact on imp roving t he environm ent. The col lective efforts of

individuals can o ften b e the m ost p ow erful of al l.


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Who is Sustainable Energy Ireland?

Sustainable Energy Ireland (SEI) was set up by the government in 2002 as Irelands

national energy agency with a mission to promote and assist the development of

sustainab le energy.SEIs activit ies can be d ivided in to tw o m ain areas:

Energy Use -Energy is vital to how we live our daily l ives but most of us dont use

energy as efficient ly as w e could. By assistin g th ose wh o u se energy (m ainly ind ustry,

bu sinesses and ho useho lders),to be m ore energy efficient, SEI can help to reduce th e

amou nt of energy w e use overal l .

Renewable Energy -Energy t hat is gen erated from renew able sou rces such as w ind

and solar po wer is clean and do esnt prod uce harmful g reenho use gases. By

prom oting th e developm ent and w ider use of renew able energy in Ireland SEI canhelp to fu rther benefi t the environm ent, in part icular reducing th e threat of cl im ate

change.

SEI is also involved in other activities such as stimulating research and development,

advising on energ y policy and pro du cing energy statistics.

Sustainab le Energy Ireland is fund ed b y th e National Developm ent Plan 2000-2006 w ith

prog ram m es part f inanced by t he European Union.

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Did you know

Energy use is responsible for two-th irds of Irelands greenhouse gas emissions.

Irish homes use around a quarter of all energy used in the country thatseven more t han industry.

The average home consumes almost 40% more electr icity than it did in 1990.

Renewable energy currently accounts for just 2% of Irelands energy supply.


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Planning & Building an Energy Efficient Hom e

While the Building Regulations require

that new bui ld ings achieve minimumstandards of energy ef f iciency, high er

levels are in many cases worthwhile.

Since a house being built today can be

expected to be occupied for 60 years or

m ore,an energy-efficient design can yield

considerab le savings over it s lifetim e.

Although some energy-saving measures

can be implemented at a later stage,retrofitting is often more expensive and

less effective than incorporation when

th e house is being bu ilt .

Apart from reducing fuel and electricity bills,an energy-efficient home design can

provide imp roved com fort for occupants w hile helping to p rotect the environm ent.

It can also p rovid e insurance against fu tu re increases in fu el costs.

This leaflet aims to provide tip s on energy efficiency to t ho se plannin g t o b uild (orbu y) a new hom e. It is not comp rehensive the range of details for energy-eff icient

hou se design is too w ide for that.


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1 Fundamental Planning Decisions

Site selection

Energy used in driving from place to place can am oun t to a signif icant p ropo rt ion

of a ho useholds tot al energy consum pt ion. By locating new hou ses near to w ork-

places, schools, pu blic transpo rt routes, etc., transpor t energy consum pt ion can be

reduced.

Transmission of sunshine through windows (passive solar heating) can reduce

heating costs.The selection of a site w hich is exposed t o t he low -altitu de w inter sun

can allow for p assive solar heatin g.

By selecting a location sheltered from th e w ind, heat loss from th e bu ilding can be

reduced.Shelter can b e provided by nearby trees,adjacent bu ilding s or surrou nd ing

hil ls. If no such shelter exists, it can b e provided in t im e throu gh planting trees or

shrubs.

In som e,m ainly rural,locations th ere may be po tent ial for renew able energy sou rces

other th an solar, for example hydropow er, w ind pow er, wo od, biogas, or heat w hich

can b e extracted from the g round or sea. The po ssibil i ty of ob taining h eat from a

comb ined heat and pow er plant or group heating scheme m ay also inf luence the

selection of a site.

Winter Sun

ShelterWind


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Building form and orientat ion

A comp act b uilding form o f m inim um surface-to-volum e ratio is best for reducing

heat loss. How ever, a rectangular building w ith o ne of t he long er facades facing

sou th can allow for increased passive solar heating, day-ligh tin g and n atural

ventilation . As w ell as reducing energy costs, sunny sou th -facing roo m s also have

high amenity value.

Projection s such as bay and dorm er wind ow s shou ld b e kept to a minim um , since

by increasing t he sur face-to-volum e ratio o f the bu ilding , th ey w ill increase heat

loss.They also t end to be m ore d ifficult to insulate effectively.

Pitched roofs should have one slope oriented south to al low for opt imum

per form ance of a roof-m ount ed or roo f-integrated active solar heating system .Evenif such a system is not planned during construction, it m ay be installed at som e

stage during the l i fe of th e building.

Energy assessment

Many d ecisions affecting t he energy p erform ance of a house are taken early in th e

design p rocess. A meth od o f calculating ann ual heating energy consump tion

should be used to com pare alternatives at th e prelim inary design stage.


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2 Building Fabric and Structure

Insulation

Levels of insulation higher than those required in the Building Regulations are in

m any cases econom ically justified. Insulation should b e well distrib ut ed around t he

bu ilding shell.It is bet ter to h ave a go od overall level of insulation t han, for exam ple,

a highly insulated f loor w ith n o roo f insulation.

Attention should be given

to the avoidance of therm al

br idg es. These are shor t

c ircui ts across insulat ion,w hich are com m only found

at lintels, jamb s and sills of

doors and w indow s, and at

junct io ns w here flo ors and

ceilings meet external walls.

They give rise to increased

heat loss and possible

condensation prob lems.

There are many exam ples of b uildings perform ing m ore po orly than expected in

energy terms due to po or q uality w orkm anship in install ing insulation. To achieve

th e level of energy efficiency predicted b y th e design, it is very imp ortant to ensure

goo d q uality w orkm anship and sup ervision du ring construction.

Ventilation

Adequate ventilation is essential to provide fresh air and to remove moisture,

od ou rs and po llutant s. How ever, excessive ventilation d uring t he heating season

results in energy w astage and can also cause discom fort du e to draug ht s.

Con tro lled vents sho uld b e installed in every room ;t rickle or slot vent s incorporated

in w ind ow frames can ensure a reason able am ount of cont inuo us fresh air and can

be op ened up o r closed dow n to a m inimu m as required.

Insulation

Brick

Brick Jamb

Thermal Bridge

Door


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Cooker hoods and sm all fan exhausts allow for cont rolled rem oval of m oist air from

kitchens and b athroom s, and p revent t his air being d raw n int o l iving or b edroom s.

Attent ion should be given, during b oth design and construct ion, to ensuring that

th e bu ilding is w ell sealed.Services shou ld b e designed w ith m inimu m penetration

of pip ework and cabling thro ugh the b uildings insulated shell.Doo rs and w indo w sshould com e wit h factory-app lied draught seals. Porches and d raugh t lob bies can

reduce draught s at external doo rs.

Never seal up a hou se com pletely, as a min im um of fresh air is required fo r health

and safety reasons.

If an open fire or other fuel-bu rning fireplace app liances are to b e installed, th ey

should h ave an ind epend ent air sup ply. This can b e achieved b y means of an

underfloor draught or by using a room sealed appliance such as a balanced flue

heater.

A balanced vent ilation system involving fans, du ctw ork and a heat exchanger can

transfer heat from warm stale outgoing air to incoming fresh air (this is called

m echanical ventilation w ith heat recovery). Stale air is usually extracted from

room s such as kitchens and b athroom s, and w arm ed fresh air sup plied to l iving

room s and bedroo m s.

For such system s to work w ell,

the hou se m ust b e well sealed.

Correctly sized systems can

reduce ventilation heat loss

considerably.

If the house is to be b uilt in an

area where leakage of radon

gas from the ground gives riseto concern, appropriate steps

should be taken to prevent

its entry into the house.

The Radiological Protection

Instit ute of Ireland can advise

on t his.

Heat Exchanger

Cooled Stale Air

WarmStale Air

WarmedFresh Air

Cold Fresh Air


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Passive solar features

If the ho use is exposed t o th e low-al t i tude w inter sun, glazing shou ld be

concentrated on t he sout h facade. Window area on t he nor th facade shou ld be

m inim ised to lim it heat loss.Thermal mass w ith in sou th -facing room s, e.g. m ason ry

w alls or concrete floors, can absorb and store solar energy durin g t he day and

release it g radually during t he evening . The heating system should have a fast

response time and good controls to maximise the usefulness of solar gains.

Overheating protection in south-facing rooms in summer can be provided by

overhang ing eaves, blinds,natural ventilation , th ermal mass or oth er m eans.

In general,it is no t w ise to increase

south-facing glazed areas too

dramatically. Otherw ise addit ionalm easures w ill be required to avoid

overheat ing in summer and

excessive heat lo ss at n igh t and o n

overcast d ays in w int er.

Windows should have a high

resistance to h eat loss. Low -

emissivity dou ble glazing, w hich has a special coating to redu ce heat loss, is

required.

Well-f i t t ing curtains can help t o retain heat at nigh t. If a radiator is m oun ted b elow

th e wind ow, the curtains shou ld not cover it w hen closed,b ut should rest l ight ly on

a win dow -board or shelf above the radiator.This arrang ement w il l direct w arm air

f rom t he radiator into t he room rather than up behind t he curtain.

South-facing North-facing


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A w ell-designed sunspace or conservato ry on

the south side of a building can reduce the

heating needs of a house by acting as a buffer

against heat loss and collecting solar energy

on f ine days. However, t here are many

exam ples of sunspaces, po orly design ed froman energy point of v iew, w hich increase

heating requirem ents. Sunspaces shou ld not

be heated, and shou ld be separated from t he

heated space by w alls and / or closable d oors /

w indow s. They should n ot be regarded as

being h abitable all year round . The energy

losses from one heated sunspace can negate

the savings of t en unheated ones!

Building materials

The emb od ied energy of a produ ct is th e energy used to prod uce it , and includes

energy used in extracting raw m aterials, pro cessing and t ranspo rt, e.g. Irish-grow n

tim ber w il l incur low er transpor t energy use than t im ber im po rted from overseas.

The embodied energy of a house is typically over five times its annual energy

consumption and therefore equates to approximately 5-10% of the total energyconsum pt ion d uring t he l i fe of the hou se.

The building materials selected should have minimum environmental impact

du ring their entire l i fe cycle, includ ing m anufacture, use and dispo sal. Building

comp onent s shou ld b e designed for long l i fe and du rabil i ty, and ideally shou ld b e

recyclab le at t he end of t heir op erating lives.

Window

Wall

Radiator

Windowboard

Curtains

Insulation orreflective foil


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3 Heat ing systems

Energy efficient houses need smaller heating systems than conventional houses.

The resultin g savings w ill help to pay for th e cost o f addit ional insulation .

Boilers

The heating system should b e efficient , no t on ly at full load, bu t also at low er loads.

If looking at oi l or g as bo ilers, you shou ld ensure th at the b oiler com plies w ith t he

EU boiler efficiency directive. In the case of gas bo ilers, you sho uld con sider

condensing bo ilers, w hich cost a bit m ore bu t are high ly energy-eff icient.

If selecting individual room heaters, consider room sealed, balanced f lue unit s.

Room heaters sho uld b e correctly sized for th e room th ey are to heat and should be

thermostatically controlled.

Hot w ater system s

It is generally mo re energy-efficient t o heat w ater using an efficient bo iler or ot her

fuel-bu rning app liance than w ith an electric imm ersion h eater. The hot w atercylinder shou ld b e w ell-insulated; factory app lied insulation is generally more

effective and du rable than a lagg ing jacket. As w ell as pro viding space heating ,

comb ination comb i bo ilers sup ply hot w ater directly to t he taps, th us avoiding t he

losses associated w ith sto rage in a hot w ater cylind er.

Location/Configuration

By locating th e heating and hot w ater system s, includ ing p ipewo rk, entirely wit hin

th e insulated bu ilding shell, heat losses can b ecom e heat g ains. Ensure goo d

venti lat ion to t he bo iler and take accoun t o f f ire regulations. Attent ion shou ld b e

given t o m inim ising th e lengt hs of pip e runs and associated heat losses.


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Automat ic cont rols

Heating system controls should be installed to ensure that heat is provided only

w hen and wh ere it is needed. The Building Regulations require therm ostatic

radiator valves th at allow cont rol of tem peratu res in ind ividual room s.Separate tim e

and temperature control in two or more zones is necessary where floor area is

greater than 100m 2.

Open fires

Open f ires, w hether of the solid fuel or gas typ e, are w asteful of energy, and even

w hen t hey are not in use, the chim ney gives rise to u ncontro lled venti lat ion heat

loss. If a fireplace m ust be installed, an underflo or d raugh t air sup ply (a sm all du ctor pipe installed within the f loor and connecting the outside air directly to the

fireplace) can h elp to reduce the amou nt of w arm internal air escaping throu gh the

chim ney.A closed stove is preferable to an open fire in term s of cont rolled efficient

heat.

Solar

Active solar heating system s, includ ing a solar collecto r on a sou th -facing roof, cancontribut e to heating needs.

A solar w ater heatin g system can

provide about 60% of a familys

annual hot water requirement,

wi th back-up heat ing coming

from the convent ional system.

A solar space heating system

can cont ribute t o h eating needs,part icularly in spring and

autum n. Though the economics

of such system s m ay be m arginal

at present low fuel prices, they

use a clean, sustainable energy

source.

DOMESTIC SOLAR WATER HEATING SYSTEM

Roof-integratedsolar collector

To taps

Back-up

heating

Hot water cylinder

Pump


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4 Light ing and Appliances

Energy-efficient lamps and fittings should be chosen for all

room s w here light s are likely to be sw itched on for long p eriods

- living room s, kitchens, halls,

security light ing etc. While a

compact f luorescent lamp

(CFL) costs m ore t o bu y t han

an ordinary tungsten bulb,

the energy savings i t wi l l

yield will more than recoup the investment over

its long op erating life.

A l l f r idges, f reezers, w ashing m achines and

tumble dryers on display in shops are now

required by law to display Energy Labels

ind icating t heir energy efficiency. These labels

can assist the purchaser in selecting an energy-

eff icient m odel.

EnergyManufacturerModel

Energy Consumption kWh/year(Based on standard test results for 24 h)

Fresh food Volume 1Frozen food Volume 1

511

180140

More Efficient

Less Efficient

Noise

A

Actual consumption willdepend on how the appliance isused and where it is located

(dB(A) re 1 pW)

Further information is containedin product brochures

Norm EN153 May 1990Refrigerator Label Directive No.94/2/EC


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5 Complete package

The heating energy p erformance of a new b uilding design can be p redicted u sing a

stand ardised energy rating m etho d.The result is usually expressed in kilow att-ho urs

per square met re of floo r area per year (kWh/ m 2y). According t o t he HER m ethod, a

typical house just satisfying the 2002 Building Regulations will have a rating of

about 90 kWh/m 2y. How ever, it is po ssible to achieve a fuel con sum pt ion less th an

th is value t hroug h m easures referred t o in th is leaflet.

From early 1997, th e Technical Guidance Docum ent L to t he Building Regulation s

will incorporate a provision whereby an energy rating procedure can be used to

dem onstrate com pliance.

Householder m anual

The energy consum pt ion o f a house depends nearly as m uch on the b ehaviour of

occup ants as on the b uilding d esign. While the former is beyond the cont rol of th e

designer,he/she can provide guidance to occupants on energy-efficient operation

of t he ho use throu gh a users m anual, personal instruction, or b oth . This guid ance

could include t op ics such as the u se of t imers, control o f venti lat ion, servicing of

heating system , energy-efficient cooking t ips, etc.

Demonstration

High standards of energy-efficient building design have been demonstrated in

m any recently-constructed ho using projects in Ireland, includin g 400 low -energy

houses built around Ireland with co-funding under the EU THERMIE programme.

Som e of t hese have active solar heating system s.


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Relevant Standards

Building Regulations, 200 2

Part L: Con servatio n o f Fuel and Energ y

Part F:Ventilat ion / Part J: Heat Prod ucing Ap p liances.

ISEN 832 - Therm al perform ance of b uildin gs - calculation of en ergy use for b uildin g

- residen tial b uild ing s CEN 1998.

Useful contacts for fur ther information

For informat ion on energy eff iciency measuresSEI,Glasnevin , Dub lin 9.

For informat ion on solar heating system s

Energ y Research Group,School of Archit ectu re,U.C.D.,Richview ,Clonskeagh ,Dub lin 14.

SEI, Renew able Energy Inform ation Office, Shinagh House,Band on , Co. Cork.

For information on radon gas

Radiolog ical Protectio n Instit ut e of Ireland, 3 Clonskeagh Squ are, 119 Clonskeagh

Road,Dublin 14.

Useful pub licat ion

Green Design: Sustainable Building for Ireland ; Ann McNicholl and J. Owen Lewis

(eds), Energy Research Group, University College Du blin ; Office of Pub lic Works,

1996.

Source Text

Energy Research Group UCD

This leaflet is prin ted on pap er prod uced from 50% recycled

and de-inked fib res and 50% chlo rine free bleached p ulp (TCF).


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Read our ot her p ublications:

A Det ailed Guide t o Insulating Your Hom e

A Detailed Guide t o Home Heating Systems

Your Guide t o Renovating an Older Home

Your Guide to Renewable Energy

A Consumer Guide to Susta inab le Energy

How t o make your Home m ore Energy Efficient

SEI,Glasnevin , Dub lin 9

tel: +353 1 836 9080 www.sei.ie SEI InfoLine

Sustain ab le Energy Irelan d is fun ded by th e

Irish governm ent under the Nationa l

Developm ent Plan 2000-2006 wit h program m es

part f in anced by the European Unio n.

building energy eff home

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