briefing 09 - passive solar design - ccaa documents/ccaa... · passive solar design energy...

■ Reducing Energy Demands■ Passive Solar Systems■ Physical Principles■ Design Basics

Passive Solar DesignEnergy Efficiency Through Passive Solar Design

Introduction

Life cycle analyses have demonstrated that themajority of energy in a building is consumed inoperational energy or during the post-occupancy phase of a building's life. A universally accepted method of reducing theenergy demands of active or mechanical meansof heating and cooling buildings is throughpassive solar design. Additionally, by usingdurable, long-life materials and materials thatlower operational energy through fabric energystorage or thermal mass, significant energysavings can be made. Concrete is an extremely

durable and readily available building material.In addition to its thermal mass characteristics itis ideally placed as a key feature of passive solardesign. This briefing provides an overview of thekey issues concerning passive solar design anddesign guidance on how to best incorporatethese principles early in the design phase.

Reducing Energy DemandsThe operational energy demands of buildingscan be reduced by incorporating passive solardesign principles appropriate to the localclimate in the preliminary design stage.

09APR2003

Passive solar design concepts are particularly suited to temperate and arid zones.

Adelaide, Hobart, Melbourne, Perth, Canberra and Sydney all lie within warm,

mild and cool temperate zones.

- Briefing 09 APRIL 2003

Eight climate zones have beenidentified in Australia Figure 1:■ Zone 1: Tropical, high humidity

summer, warm winter.■ Zone 2: Sub-tropical, warm humid

summer, mild winter.■ Zone 3: Hot arid summer, warm

winter.■ Zone 4: Hot arid summer,

cool winter.■ Zone 5: Warm temperate■ Zone 6: Mild temperate■ Zone 7: Cool temperate■ Zone 8: Alpine

Passive solar design concepts areparticularly suited to the temperateand arid zones listed above. Adelaide,Hobart, Melbourne, Perth, Canberraand Sydney all lie within warm, mildand cool temperate zones so thatmost of the Australian populationlives within these three climaticzones, Zones 5, 6 and 7.

In these zones, passive solardesign exploits insulated solid orheavy building materials such asconcrete panel walls and floorslabs and clay brick masonry fortheir value-added characteristicsin conjunction with the differencein altitude angle of the sun in thesky between summer and winter.By harnessing the natural

advantage of high mass togetherwith the heat of the sun - or solarenergy - more comfortable livingconditions can be achieved withreduced reliance on space heatingor cooling, and subsequentreduced energy demands.

Concrete floors, solid internaland external walls, north-facingwindows and insulated roofs can beused in passive solar design. In the

cooler months, these elementscollect solar energy throughwindows, storing it in the high-massfloor slab/walls/ceilings, releasing itonly when the air temperature dropsbelow that of the walls and floor. Thissystem uses the heat-storagecapacity or thermal mass of thebuilding materials to moderateextremes of temperature in bothsummer and winter.

Passive Solar SystemsMost passive solar designs are of thedirect-gain type where sunlightentering through generally north-facing windows falls onto an elementof the building suitable for absorbingand storing of heat, usually aconcrete slab floor, with additionalstorage provided by solid internalwalling Figure 2. There are manyindirect gain systems - including theTrombe-Michel wall, the greenhouse,the greenhouse and rock bin, theBaer drum-wall, water-roofs andthermo-siphon systems - all of whichare well documented.

However, the direct gain systemis most often used because itrelatively easily achieved through theprovision of generous north-facingglass in any design styles.Additionally, it does not increaseconstruction costs as it relies ontraditional building materials such as a concrete floor built as a slab-on-ground. With 80% of new housing inAustralia being built on a concreteslab floor, it makes sense tocapitalise on this asset and exploit itsthermal mass resulting in greaterenergy efficiency for the users.

Direct Gain - Heating CycleAn otherwise appropriately designedbuilding should aim to have north-facing glazing of a size approximatelyone-fifth the floor area of the roomsto be warmed by the direct-gainmethod. Where a mild winter climateis experienced, the ratio of north-facingglass to area of rooms heated by directgain may be as low as one eighth.

Having provided adequatenorthern glazing for the living area,the effect of direct gain heatingshould be optimised as follows:■ Use concrete as floor slabs, wall

Figure 2 Typical altitude angles at12.00pm for north-facing wall,latitude 350 South (Sydney NSW,Canberra ACT, Adelaide, Albany WA)

33°

56°

79°

WINTERSOLSTICE

June 21

EQUINOXMarch 21/

September 23

SUMMERSOLSTICE

December 22

Figure 1 Climate map (Courtesy of Australian Building Codes Board, © Copyright Commonwealth of Australia 2002)

panels, structural elements - suchas beams and columns - ceilingsoffits or interior features such ascabinetry benchtops, staircases.

■ In temperate and cool temperatezones insulate the windows withpelmet-hung, close-fitting, heavywall furnishings such as curtains,which should be drawn aftersunset. In severely cold climatesdouble glazing or insulatedwindow shutters may prove

economically viable Figure 3.■ Insulate the ceiling to prevent heat

loss from the thermal storesduring the day and from the roomat night and specify R-values forall relevant elements (walls,floors) and introduce energyefficiency measures in accordancewith the Building Code ofAustralia.

■ Seal around all wall penetrationsto prevent heat loss by excessiveair leaks.

■ Ideally carpets or rugs should notbe laid over slabs receiving wintersunlight.

■ Insulate the edges of the slab-on-ground floor, especially thenorthern edge that acts as theprime heat store, reducing heatloss to the earth. Thickening ofthe slab to the depth of 250mm in

a two-metre-wide strip along thisnorthern edge and insulating theouter face of internal masonryleaf of external walls may also beconsidered Figures 4 and 5.

Direct Gain - Cooling CycleA common failure of many low-energy designs in temperateAustralia is that they cater only forthe winter heating cycle and forgetthe summer cooling cycle. It is vitalto provide cross-ventilation in abuilding in summer to not onlysupply fresh air but also:■ Give instantaneous cooling

whenever the inside temperatureis higher than the outside one;

■ Remove overnight the heat storedin the building fabric during theday commonly referred to as nightpurging; and

■ Provide the feeling of cooling onthe skin by accelerating itsevaporative cooling (this can alsobe provided by the use of fans,particularly ceiling fans) Figure 6Solar shading should be

configured over the northernwindows to exclude access to mostsummer sun to the interior spaces.Additionally, it is desirable to provideextra shading by a pergola plantedwith deciduous vines, brise soleil oradjustable (fabric or metal) blinds onthe northern windows to protectthem from heat gain in unseasonablyhot weather occurring in earlyautumn or late spring.

As the outside air temperatureincreases during a summer day the

Briefing 09 APRIL 2003 -

Low-angled winter sunpenetrates under eaves

Direct and reflectedradiation absorbedby heavy-weightwalling elementssuch as concretepanels or masonry

Pelmet-hung heavy curtainto be drawn after sunset

Insulated ceiling

North-facing, concrete floorwarmed by solar radiation

Reflective foil sarking

Figure 4 Slab-edge insulation insevere cold climate areas

Concrete floor slab

Building-grade polystyrene board protectedwith fibre-cement sheeting

Damproofmembrane

Heavy-weight walls ofconcrete panel ormasonry

INTERIOR

Internalleaf

Externalleaf

Insulate outer faceof heavy-weight(concrete wallpanels or masonry)internal leaf.Insulation materialssuch as styrene-foam board orsingle-sidedreflective-foillaminates, shouldbe installed inaccordance withmanufacturer'sinstructions

Figure 5 Insulation of cavity wallin severe cold climate areas

Eaves shade glassfrom high-angledsummer sun

Heavy-weight walls(of concrete panels or masonry)and concrete floor, absorbheat from internal air

Open windows allowcross-ventilation

Insulated ceiling

Concrete floor temperature modifiedby cool, deep-earth temperature

Reflective foil sarking

Figure 6 Direct gain-cooling cycle

Figure 3 Direct gain-heating cycle


inside air temperature is modified bythe walls and floor absorbing heatfrom the air. Additional efficienciescan be introduced into the direct-gaincooling cycle by:■ Fostering vegetation near the

southern-side openings used forventilation - if these plants arewatered in summer the airpassing through them will bepartly cooled before entering theinternal space;

■ Planting deciduous trees or vineson the northern and western sidesof a building to provide shade insummer and admit sunlight inwinter;

■ In sub-tropical and tropical humidzones and in humid areas of otherzones, adopting a design with aventilated space between theroofing and the ceiling;

■ Adding suitable insulation underthe roofing material.

Physical PrinciplesThe Nature of Solar EnergyThe sun's energy travels throughspace as a wide spectrum of waves;the shortest is less than a millionthof a centimetre, the longest morethan a kilometre. Solar radiation isclassified by the length of thesewaves. Some 95% of heat energyradiating from the sun is contained ina relatively small segment of shortwaves in the spectrum Figure 7.

Up to 53% of solar radiationintercepted by earth is reflected backinto space. Latitude and local climaticfactors further reduce the amount ofradiation received. Australia generallyreceives about 47% of solar radiationentering the atmosphere.

Incident RadiationWhen sunlight strikes a surface,radiation waves may be reflected,transmitted or absorbed in anycombination depending on thesurface texture and colour and onthe clarity of the material Figure 8. A rough surface scatters reflectedsunlight, while a smooth surfacereflects it uniformly at the angle ofincidence. A white glossy surface willreflect more than 80% of the solarradiation falling on it, while a roughblack surface may reflect only fivepercent. Clear materials, such asglass, allow almost 90% of the solarradiation to pass straight through.

Glasshouse PrincipleThe characteristic of glass totransmit nearly all solar (short-wave)radiation it intercepts while at thesame time absorbing most thermal(long-wave) radiation is important.

The temperature build-up in aclosed car on a sunny but cold day isevidence of the dual characteristic ofglass. Solar energy, streaming inthrough the windows is absorbed byinterior materials and re-radiated aslong-wave radiation to the interiorspace, but is unable to pass throughthe glass to the outside. The re-radiated long-wave thermal radiationis then deflected back to the interiorthus heating it even further. Thisprinciple is used to grow plants incold climates inside glass-houses orgreenhouses Figure 9.

Heat Storage CapacityAny material that absorbs solarradiation is heated. The amount ofheat that can be stored in thatmaterial is measured by itsvolumetric heat capacity, a function

Approximately10% reflected

As little as5% reflected

Up to70% reflected

Up to 90% passesstraight through

CLEAR GLASS ROUGH BLACK SURFACE SMOOTH WHITE SURFACE

Up to 95% ofheat energyabsorbed

Figure 8 Incident solar radiation

Figure 7 The nature of solar radiation

Solar radiationpasses through theclear atmosphere

Some solar radiation isreflected by the earthand the atmosphere

Infra-red radiationis emitted from theearth's surface

Some infra-red radiation isabsorbed and re-emitted bythe greenhouse gasses, thuswarming the earth's surfaceand the lower atmosphereMost radiation is

absorbed by theearth's surface andwarms it

EARTH

ATMOSPHERE

Heavy floor andwalls store andre-radiate heat

Glass istransparentto short-wavesolar radiation

Glass deflects long-wave, re-radiatedheat which heats the inside air resultingin higher temperature inside than out

Insulated ceiling

Figure 9 The glasshouse principle


of a material's density and specificheat. The higher the volumetricheat capacity, the greater thematerial's potential for the storageof solar energy Table 1.

Concrete and solid masonrymaterials possess a naturaladvantage in heat storage capacity(thermal mass) which is magnified bythe normal thickness or volume ofthese materials when used inconstruction. Hence, concrete floorsand solid masonry walls provideuseful thermal mass in a building.

The use of concrete slab floorsfor thermal mass is particularlyimportant, as most of the sunlightpassing through the windows falls onthe floor. Favourably conductingsurface materials such as quarrytiles, slate or vinyl should be used onfloors receiving sunlight if the slab isto be covered for aesthetic reasons.Increasingly, concrete floor slabs areleft polished as exposed or patternedfloor finishes. While there is someadvantage in a darker colour if mostof the floor is actually sunlit, there isalso advantage in using mid-rangecoloured materials if only part of thefloor is in the sun at any one time.Reflecting some of the solarradiation is the most effective way ofdistributing it to other thermallymassive surfaces, such as walls,elsewhere in the direct gain space.Insulating floor coverings such ascarpet, cork tiles or coir matting limitthe potential advantages of thethermal mass of the floor.

High thermal mass is useful inareas not exposed to direct orreflected solar radiation in two ways.

In hot weather thermally massivefloors and walls absorb heat from theinternal air. When insulated from theoutside air temperature, thermallymassive elements reduce the fluc-

tuation between extremes of temp-erature in both summer and winter.

Thermal MassThe physical principles of solarthermal energy have been outlined todescribe the receipt, absorption andstorage of this free energy source. Intemperate climates insulated solidwalls and floors have an advantage inconditioning the internal environmentdue to diurnal temperature swingsand the time lag decrement of thethermal mass. In winter the thermalmass in a correctly designed spacewill store daily heat gains to bedistributed later in the day whentemperatures drop. Similarly, insummer heat, the slab acts as agiant cooling element. The floor slabbenefits from the earth's near-constant low temperature and links

YARRALUMLA HOUSEThe precast concrete construction incorporates an insulated concrete sandwichpanel system giving a high R-value and thermal mass.The residence is designed to passive solar principles.

Architect Rick Butt, Strine DesignStructural Engineer Jerin HingeeBuilding Type Residence. Two storey, detachedClimate Cool TemperatePhotography Bernie den Hertog, VR Grafix

Table 1

Thickness Density R-value C-ValueThermal Capacitance

Material (mm) (kg/m2) (m2K/W) (kJ/m2K)

Solid Concrete Wall 150 2300 0.26 300

Solid Concrete Wallor Floor Slab 100 2300 0.23 200

Clay Masonry Veneer 110 1600 0.18* 163*

Timber Frame/Weatherboard Cladding 12 500 0.47 12

Glass Curtain Wall 6 2500 0.16 1

* As measured by CSIRO

to the thermal storage capacity of theinternal skin of solid cavity wallconstruction so that the whole reactsslowly to outside temperaturefluctuations, reducing dependence onenergy for heating or cooling toproduce comfortable internaltemperatures. In sub-tropical,tropical and alpine zones the benefitsof using high-thermal-mass wallingwill be discussed in detail in futurepapers. Energy-efficient designconcepts must always be consideredcarefully so that the combination ofelements incorporated into a struc-ture suit local climatic conditions andthe peculiarities of a particular site.

Slab edge insulation is recomm-ended when slab-embedded electriccables or water pipes are used forspace heating (and in severe coldclimates as previously mentioned).

In addition, the benefit from the area of a concrete slab thatreceives direct solar radiation canbe optimised as a storage mediumif it is thickened or it is insulatedfrom the ground.

The benefits of undergroundhousing as protection from extremesof temperature, such as at the opal-mining town of Coober Pedy in SouthAustralia, are well known. Mildclimate areas do not justifycompletely underground buildings;

however, earth-sheltered housing isvery energy efficient. Walls must bedesigned as simple retaining wallsthat can be achieved economicallywith reinforced, concrete-filled,hollow, concrete blocks. Particularattention must be paid towaterproofing the retaining wall andconcrete roof if used. Drainage andinsulation also need to be considered.

Design BasicsOrientationResidential buildings designed tocapitalise on the benefits of solarenergy should be planned with livingareas placed to admit the sun in thecooler months. The key to a housethat is naturally warmer in winterand cooler in summer is the effect ofthe combination of the earth'sdiurnal rotation about it's axis andthe tilt of the earth's axis in relationto its orbit around the sun. The diurnalrotation causes the change fromnight to day and the tilted axisproduces summer and winter as theearth orbits the sun Figure 10.

These phenomena cause thesun's position in the sky to appearhigher at noon in summer than inwinter and daylight to extend for alonger period in summer.

It is important to be aware of the

position of true north, that the sun'saltitude in the sky varies with latitude,and of the variation this causes toangles of sun penetration into a roomdepending on the location of a site.There are many publications thatelaborate on this point, of which themost often used is Sunshine andShade in Australasia, R. O. Phillips,CSIRO Technical report No. 92/2

When glass is oriented to the northit is essential to provide an eavesoverhang which allows sun penetrationin winter but excludes it in summer.The extent of this overhang can beeasily calculated according to locationusing the eaves overhang design chartFigure 15. It is also essential to ensurethat plenty of sun can reach the glassin winter and is not obstructed byvegetation or neighbouring property.

Design for ClimateHousing should be designed to suitthe particular climate of its location,for the comfort of its occupants andfor energy efficiency. Climate canchange dramatically within oneclimate zone depending on whetherthe location is coastal, alpine(mountainous) or arid (desert) and itslatitude. Climate can also changemarkedly from one valley to the next,by the orientation of a slope or by the effect of prevailing winds. Anintimate knowledge of the particularclimate of the area in which a houseis to be built is therefore of immensebenefit in designing appropriately forthat location.

Australian climate types can besummarised as follows:■ Tropical humid: high humidity

summer, warm winter includesthe remainder of the north-western, northern and north-eastern coastline of Australia andis characterised by high humidityduring the wet season andmoderately high daytimetemperatures throughout the year.

■ Sub-tropical: warm humidsummer, mild winter includes thecoastal area extending from thenorthern NSW coast, throughBrisbane, to Mackay.

■ Hot arid summer, warm winterand hot arid summer, mild winterwhere there is a wide range of


Observer

Zenith

Mer

idia

n

Summ

er

Summer

Equinox

Equinox

Winter

Winter

Azmuthat sunrise

Altitudesat noon

SS

WW NN

EE

Figure 10 Pattern of sun’s seasonal movement


Cold winds

Deciduousshade trees

Pergola

Trees to shieldagainst wind

Solar heat gain in winter(thermal mass)

B

B B F

K D L carport

Wall to shadeagainst latesummer sun

Creepers on wall

Figure 11 Planning for temperate zones

KANGALOON HOUSEInsulated high thermal mass interior showing internal concrete block walls by Boral Besser, honed face alabaster mix. The concrete slab on ground, insulated with rigid PVC to 1.4 m around the perimeter, was polished and sealed by the builder.

Architect Peter Stronach, Allen Jack + Cottier in assocation with Tim Allison and AssociatesStructural Engineer Taylor Thompson WhittingBuilding Type Residence. Two storey, detachedClimate Warm TemperatePhotography Peter HyattAwards Francis Greenway Society Green Building Awards, 2002 Gold Medal

Kangaloon House: Outdoor Terraceadjacent to living area with verandahproviding climate protection andsummer shading to the residence.


temperature in summer, with veryhigh daytime temperatures of 35to 40°C and cooler night-timeconditions of 20 to 25°C withvarying breezes. Locations suchas Alice Springs can benefitsignificantly from passive solardesign coupled with high thermalmass construction.

■ Warm temperate characterisedby hot summers and cool tochilly but generally sunny wintersMajor urban centres located inthis zone include Perth, Adelaideand Sydney.

■ Mild temperate consisting of thecoastal areas from the south ofAdelaide through to Melbourneand further around the coast tothe south of Wollongong.Additionally, west southern coastalareas from Albany to Pembertonand inland from Esperance to thesouth of Belladonia. Inland areasof South Australia, Victoria andNew South Wales are alsoincluded. Summer temperaturesgenerally average at about 270Cand so the demand for cooling islow although designs mustprevent overheating in summer.There is however a universal needfor winter heating.

■ Cool temperate including most ofTasmania, inland western districtof Victoria, some areas of the SnowyMountains and central tablelands ofNSW, Canberra, and the VictorianHigh Range Country. The majordesign consideration is winterheating, but it is also important to avoid overheating in summer.

■ Alpine areas are limited to highaltitude areas of Tasmania,Victorian High Range Country,Snowy Mountains and the centraltablelands of NSW.

A thorough knowledge of themicro-climate of a particular site, thedirection of cooling summer breezes,cold winter winds, wind-borne dust,etc should be the most importantinfluence on design and aresummarised below.

PlanningIn temperate climates buildings thatare longer in the east-west than inthe north-south direction are more

efficient for both winter heating andsummer cooling. This orientationallows for maximum glazing to thenorth and minimum east-westexposure to morning and afternoonsun Figure 11.

This does not mean that allbuildings must be so oriented.Different building shapes can bedesigned which satisfy the particularproblems of each site by using theshape of the building, number oflevels, and particularly effectiveglazing including the use ofclerestory windows and roof lights,combined with adequate shading.

Hot arid climates demandmassive construction with ability tonight purge with cool breezes andcross ventilation to re-charge thethermal mass for the following day.Humid climates demand a focus oncross-ventilation, particularly inthe bedrooms Figures 12, 13 and 14.

Inside SpacesWhen the location, generalorientation and shape of the buildingis decided, the organisation ofinterior spaces is the nextconsideration. In temperate climatesliving spaces should be placed along

Courtyard walls screenagainst wind and dust

Outdoor living

Pergola withadjustableshading

Massiveconstruction

Lightweightconstruction

Sliding doorsfor breeze

Small windows

K D L

Garage

Garage shades wallfrom late afternoon sun

B B B

Courtyard forevening use

Figure 13 Planning for hot arid zones

Figure 12 Ventilation strategies

Extract ventilation

Sunlight

Naturallight

cross-ventilation

cross-ventilation


Trees toshield fromwind

Bulk-insulatedwall

Bulk-insulatedwall

CarportB B B

L

D

F

K

Ceiling fans

Vertical shading

Privacy screen

Opening panels or louver wallsfor cross-ventilation

Figure 14 Planning for sub-tropical humid zones

MULLUMBIMBY HOUSEHigh thermal mass internal elements include concrete floor slab, concrete fireplace hearth, concrete panel walling. Additionallyhandmade Balinese temple blocks seen in the foreground were hand tamped in a traditional high-repeat use mould.

Architect Chris Barnett, Sustainable Built EnvironmentsStructural Engineer Phil WallaceBuilding Type Residence. Two storey, detachedClimate Sub-tropical HumidPhotography Rod Bell


the north face of the building. Leastoccupied spaces - such as storageareas, circulation areas and garages- should be placed along the southwhere they act as a buffer betweenliving space and the cooler southernwall. Rooms that may benefit frommorning sunlight, like bedrooms,bathrooms or kitchen areas shouldbe on the east wall. However,children's bedrooms can benefit fromnorthern sunlight if they are to beused extensively for play or study.Attention should always be given toparticular local climatic conditions.

Walls, Windows and DoorsInternal walls can add substantiallyto the thermal mass of a building.External walls should act asinsulation surrounding thermallymassive internal elements.

Windows are necessary for lightand ventilation and play an importantrole in the collection and retention ofsolar radiant energy. In each wall,however, they need to be treateddifferently.■ North-facing walls have the

greatest potential exposure tosunlight with ample heat-absorbing and storage materialbehind the glass. However, theymust be provided with appropriatesunshading devices such as eavesto allow winter sun penetrationbut exclude summer sun.

■ Full-height glazing in the northernwall of a house is often providedby sliding glass doors openingonto a patio or verandah.

■ East-facing walls may have a fewwindows intended to catchmorning sunlight that can bepleasant in any season in atemperate climate, howevernorth-east orientation should beused judiciously it is a potentialsource of excessive solar gain insummer months.

■ South-facing walls never getuseful direct sunlight in temperateAustralia. As a result the southwalls should have only theminimum area of windowsrequired for lighting, ventilationand to admit cooling summerbreezes or double glazing if theviews are to the south.

■ West-facing walls should alsohave minimal windows and beshaded with external awnings,verandahs or deciduousvegetation against the penetrationof the low summer afternoon sun.

■ In temperate and cold climates allopenings in a wall such aswindows, doors or any otherpenetration should be sealedaround their perimeter to preventseepage of air (infiltration).

The front and rear entry doors, because of their frequent use, deserve special consideration. Infiltration around the frames may be controlled with self-adhesive sponge or mohair strips and a draught-excluder bar at the threshold. By recessing entry doors, protection against prevailing winds improves the performance of the door sealing. The planning of a small enclosed space or entry vestibule may be considered to act as an air lock, preventing further losses, especially in cool temperate climates. For rear doors, a laundry may provide thisvestibule space.

ConclusionMost of Australia's population lives intemperate Australia with smallerseasonal climatic variations andconsequently low heating and coolingcosts compared to Europe or NorthAmerica. Significant increases in thecapital cost to buildings to saveenergy are unnecessary wheredesign incorporates passive solartechniques that require little or noextra capital outlay. Climateresponsive techniques can also beapplied to those areas where climaticchanges are most extreme, by including modifications such asparticular attention to ventilation inhumid areas, or double glazing, extrainsulation and heavy curtains onareas of extreme cold in winter.If buildings are correctly plannedwith regard to orientation and solarpenetration, and the mostadvantageous materials are thenselected and used with anunderstanding of their physicalproperties - particularly thermal

mass - then comfortable livingconditions will be achieved, resultingin reduced demand on energy forspace heating or cooling.

The following are various passivedesign concepts worthy ofconsideration when building intemperate regions of Australia:■ Use insulated concrete elements

such as slab-on-ground floors, wallpanels, ceiling/roof slabs andsuspended upper storey floors to actas exposed internal thermal mass;

■ Plan for maximum northorientation of windows withshading strategies for warmers months;

■ If a concrete slab is to be coveredwith applied finishes, provide hardsurfaces such as tiles;

■ Carefully design sunshading suchas eaves, verandahs or buildingoverhangs and provide windowswith blinds or curtain;

■ Reduce windows in walls otherthan north-facing or specify asdouble glazing;

■ Plant deciduous trees and shrubsfor summer shade;

■ Consider earth shelteredconstruction; and

■ Consider extending the thickenedarea of the northern slab edgewhere sunlight falls.

These two points are true for allAustralian climates;■ Insulate the edges of the concrete

slab-on-ground in severe coldclimate areas;

■ Foster plentiful foliage aroundsouthern summer air intakes.


22 Dec(summer solstice)

27 Nov

16 Jan

26 Feb

21 Mar

14 April

26 May

E

E = C x H

WhereC = Coefficient from the chart

H

19 July

31 Aug

23 Sept

0 5

Equinox

10 15 25

LATITUDE (degrees)

TIME OF THE YEAR

Arrows showdirection oftravel ofsun

CO

EFFI

CIE

NT,

C

30 35 40 45

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.750.800.850.900.951.00

Example, 5° latitude ■

Darwin ■

Cairns ■

Townsville ■

Mackay ■ Mount Isa ■ Port Hedland ■

Rockhampton ■ Alice Springs ■

Brisbane ■

Geraldton ■

Port Macquarie ■ Tamworth ■ Kalgoorlie ■

Broken Hill ■ Perth ■

Newcastle ■ Whyalla ■ Bunbury ■

Sydney ■ Bathurst ■

Canberra ■ Wagga Wagga ■ Adelaide ■ Albany ■

Albury ■

Bendigo ■

Melbourne ■

Launceston ■

Hobart ■

17 Oct

21 June(winter solstice)

20

Figure 15 Eaves overhang design chart

09APR2003

ACKNOWLEDGMENTS

Steve King - Associate DirectorCentre for Sustainable BuiltEnvironments (SOLARCH)University of New South Wales

Geoff Clark Troppo Queensland

Dr Richard Hyde - Director Centre for Sustainable DesignUniversity of Queensland

Rick Butt - ArchitectStrine Homes

This publication replaces:

Kell, D. (ed.), Energy Saving UsingPassive Solar Design - G71, Cementand Concrete Association ofAustralia, 1994.

REFERENCES

Glass, J., Fabric Energy Storage withPrecast Concrete, Oxford Centre forSustainable Development, OxfordBrookes University, 2000.

Vale, B. & Vale, R. 2000, TheAutonomous House, Thames andHudson.

Thomas, G. & Donn, M., DesigningComfortable Homes, Cement andConcrete Association of New Zealand& Energy Efficiency ConservationCouncil 2001.

Munn, C. & Gjerde, M., BuildingComfortable Homes, Cement andConcrete Association of New Zealand& Energy Efficiency ConservationCouncil, 2002.

Slattery, K. & Guirguis, S., Life Cycle Assessment of Buildings in Australia, Cement and ConcreteAssociation of Australia,(www.concrete.net.au), 2001.

Kwok, G. (ed.), Concrete Panel HomesHandbook, Cement and ConcreteAssociation of Australia, 2001.

Nervegna, L. (ed.), MIX Volume 10,Cement and Concrete Association ofAustralia, 2002.

Phillips, R. O., (6th Edition) Sunshineand Shade in Australia; TechnicalReport 92/2, CSIRO Division ofBuilding Construction andEngineering, 1992.

Roaf, S., Fuentes, M. & Thomas, S.,Ecohouse: A Design Guide,Architectural Press, 2001.

Ballinger J A et al, Energy EfficientAustralian Housing, SecondaryEdition, Australian GovernmentPublishing Service, 1992.

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