Building ‘green’ in Cambodia

Architectural principles andpassive systems

Geoff PylePyle Architects

9 November 2010, Manolis House, Phnom Penh

Green is one issue among manydesign criteria

Green design fundamentally affectsthe building

Green is more than just energy…

Five groups of issues

1The Site

Current use of the land.Transport to and from.

Control of pollution, includingduring construction.

Solar reflectance and ‘heat-island’effect.

2Water

Rain water absorption and run-off.Processing of sewage drainage.

Collection and reuse of rainwater.

3Materials

Embodied energy.Recyclability.

Waste (during construction and use).Sustainable timber.

4Indoor environment and health

Air quality.Pollutants.

Daylight and views.User control of environment.

5Energy

Minimise energy demand through design.Lighting and cooling (design of building

envelope, and efficient systems).Water heating.

Renewable on-site generation may bepossible.

Pre-designThree questions to ask…

1In designing green, where will we place

our emphasis?If we cant do 100% of everything, what

do we prioritise?

This has to be decided for each project.

2Are we going to assess how green we

are and if so how?

Will we do comparisons of carbon/energy/cost?

3Will we validate it through an externalorganisation and get a certificate of

green-ness?

Possible benefits: assurance that green is thorough;most effective for capital investment; and marketing

advantage.

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Passive and active systems

Outline approaches totemperature and the building

envelope…

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No air-con : basics - what creates thermal comfort?

1 Shade from direct sun

2 Limit radiant heatfrom surfaces nearby(insulation?).

3 Evaporative coolingfrom skin through airmovement (fans orwind) assisted bywater/plants if possible.

Note: these slides show broad general principles, whichshould be reviewed in particular design situations…

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No air-con : insulated roofs (either flat or sloping)

Insulate roof to‘cool’ the innersurface andreduce radiationinternally

OK

Roof heats up;radiation from roof

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No air-con : insulation plus double roof

OK+ Better than justinsulated singleroof

Only 50% of originalradiation is emitteddownwards

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No air-con High double roof

OK

Due to distance betweenroofs, effect of radiation isreduced, so no real benefit ininsulating lower roof

Only 50% of originalradiation is emitteddownwards

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No air-con : walls similar in principle to roofs

OK No need toinsulate if nosun on wall

Sameprinciplesapply to wallswhich areexposed to sun

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No air-con : natural cooling at night may be effective

Night cooling ventilationthrough floors may be possible

Cross-ventilation; cooling the thermal mass of structure (concrete)at night - the concrete cools the space the following morning

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Air-con : typical - minimise heat gain from outsideAir tight jointsto prevent airleakage

Insulation

Limit electriclights by useof daylightDesignwindowscarefully

28C-35CRH 70-85%

23C-25CRH 50-60%

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Air-con : how to do windows

Clear glass : about 80% ofheat is transmitted

“The real cost ofremoving the heat thatenters a buildingthrough the windows isso great that it iseconomic to spendconsiderable sums ofmoney to reduce solarheat gain.”D G Stephenson, NationalResearch Council Canada

Insulated wall : less than5% of that through clearglass

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Air-con : how to do windows

Blind heats up and radiates - noteffective in keeping out heat

Convection around the blindalso brings heat into the room

Blinds are good for controllingglare but not heat…

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Air-con : how to do windows

These are better thanclear glass but costmore, and can reducedaylight, increasingdemand for electriclighting.

Not as effective asSHADING by a longway.

Options for glass:• Reflective glass• Heat absorbing glass• Double glazing• Low-E coatings• Gas-filled• Combinations

Glassheats upandradiatedsfrom bothsides

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Air-con : how to do windows - shade

Note: if shaded,coloured glass isof no benefit.

Consider alsodouble-glazingand low-Ecoating for betterperformance.

Many options forshading glass/walls.

Use sun pathstudies and videomodelling.

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Interior quality for users: daylighting, views, glare.

Designing a Building Envelope to be ‘green’ involves bringingtogether:

Image of the building for the owner, both in terms ofstyle and how ‘green’ the building is seen to be.

Budget and materials available.

External factors: orientation, climate, noise.

Cost-benefit analyses of different approaches -and understanding how extra capitalexpenditure is to benefit operating costs.

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Briefly on materials

Generally:

Consider the ‘whole-life’performance and cost.

If higher-carbon materials last a lotlonger - they may be more cost-effective AND more sustainable.

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Briefly on materials

Insulation:

Various types available in the international market, somemore ‘green’ than others. More coming to Cambodia.

Buy as ‘green’ a type as possible, but even if not, it isbetter to insulate well - to lower energy use.

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Briefly on materials

Structure:

Steel not used so much in Cambodia, butis recyclable unlike concrete, and is moreeasily adapted.

Concrete is being used overseas nowwith low-carbon cement substitutes,which reduce the amount of cementneeded.

For every ton of cement produced,approx. 1 ton of CO2 is produced fromchemical reaction and the burning offossil fuel.

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Case study: residential resort in Siem Reap

WATER STORAGE UNDER BUILDING

SEWAGE TREATMENT UNDERTENNIS COURT

Rain water holding tanks reduce load on city mains drainage and allow use for irrigation.Sewage treatment on site means ‘clean’ water is discharged to city main drains.

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Case study: residential resort in Siem ReapWindows are shaded by balconies. Plants and trees refresh the air and lower temperatures.

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Case study: residential resort in Siem ReapApartments and stairs are naturally ventilated, in ways which provide security.Roofs and walls are insulated. Hot water provided by solar panels. Air-con is ‘efficient’ type.

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Case study: Hun Sen Library extension at RUPPMainly naturally ventilated, with some air-con spaces. Uses existing trees for shade and toprovide confortable outside spaces for students.

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Case study: Hun Sen Library extension at RUPPMain reading area lit by daylight through glass with sun-screens (trees not shown here)

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Case study: Hun Sen Library extension at RUPPMain reading area lit by daylight through glass with sun-screens (trees not shown here).Ground floor is open for use by students, with view of water.

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Case study: Hun Sen Library extension at RUPP

Air-con spaces shown blue.

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Case study: Hun Sen Library extension at RUPP

Holes in floor allow a little more night-time cooling…

Building ‘green’ in Cambodia

Thanks