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Home > Energy and transport > Renewable Energy > In the home

Renewable energy

Passive solar architecture and energy efficient

houses

  Passive solar architecture 

  Designing for your climate 

  Local considerations 

  Energy efficiency 

  House layout 

  Landscaping 

  Lighting 

  But I've already built my house... 

 

Rating your home's energy efficiency   What will it cost? 

  Case studies 

  Further links

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Passive solar architecture

Passive solar architecture is the practise of designing buildings to make the best us

the sun’s energy. In most Australian houses, this means large north facing window

that allow in the low winter sun, but have roof overhang (eaves) that stop the high

summer sun from penetrating (see sun angle diagram below). This will help to makthe house cooler during summer and warmer during winter. A well designed passiv

solar house will have comfortable, even temperatures all year round and make goo

of natural light. It will therefore require less energy to heat, cool and illuminate tha

conventional house. Hence it will also create less greenhouse gas emissions.

Designing for your climate

Australia has several distinct climate zones, and these will have a big impact on ho

 passive solar house is designed. A passive solar house designed for Hobart may no

 perform well if it is built in Darwin.

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Source: Bureau of Meterology

The Bureau of Meteorology divides Australia into three broad climate zones;

temperate, hot arid and hot humid, each with sub-zones. There are areas where the

zones overlap and don't conform to one set of climate conditions, but generally the

zones have the following design requirements:

1 Temperate 

  Summer cooling and winter heating should both be emphasised

  House design should maximise northern exposure

  The main living areas of the house should be located on the north side  There should be a high level of insulation in the ceiling, walls and floor

  The ventilation system should be designed to block hot wind in summer and

cold wind in winter. This can be done with correct placement of shrubs and

trees.

  Houses located in coastal areas should be able to make use of the cooling ef

of afternoon sea breezes

  Houses located in inland areas should consider evaporative cooling, where

fan-forced through a wet filter pad and cooled by the evaporation of water.

  Windows to the west and south-west should be shaded from summer sun.

2 Hot humid 

  Use overhead fans to circulate air and provide a cooling effect

  Trees and verandahs used to provide shade

  Vapour barriers should be used because of the high humidity

  Reflective insulation in all external walls exposed to sunlight

  Bulk and reflective insulation in the ceiling

  Concrete slab floor

  Ventilation designed to encourage air movement and take advantage of coo

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assive solar architecture and energy efficient houses - The Australian Renewable Energy Website

 breezes

  Maximise openable doors and windows for ventilation

 Notes on hot humid zone house design: There is some debate about the value of

ventilation in hot humid architecture. Ventilation is most valuable when it is from

sea breezes, though these may limited in dense urban housing developments, and a

not always available when required in other situations. Ceiling fans situated to pro

air movement over occupants guarantee cooling when it is needed. Houses can be

optimised for either minimum air conditioning costs or best performance in the absof air conditioning, but not both.

3 Hot arid 

  Thermal mass and insulation in living areas to take advantage of cool night

crucial

  Bedrooms can be low in thermal mass

  House should be designed to maximise northern exposure, and perhaps face

inward toward a courtyard

  Underground houses, earth berm and concrete slab-on-ground houses areappropriate

  Shading the roof with a vine is useful

  Landscaping should make great use of vegetation and water

  Evaporative cooling should be used, as humidity is low

  Windows should be small and high, and located only on the north and south

walls

   North facing windows should be shaded, as should any east and west facing

windows

   North of the Tropic of Capricorn, south-facing windows should also be sha

Consideration of the local environment is also vital. Are there nearby trees or build

that block the sun? Which direction does the wind come from, and at what season

time of the day?

Local considerations

The orientation of the available land will have a big impact on the design of the ho

If the house is to be built on a small block in the inner city, there may be limitation

how much north sun it will be exposed to. Small blocks that have a longer east-we

axis with narrow north facing profile mean that traditional passive solar designs ne

 be modified to maximise northern exposure.

Energy efficiency

In order to maximise the benefits of passive solar design and maintain comfortable

temperatures, there are several elements of overall house design that must be

considered.

Thermal mass is the amount of potential heat storage capacity available in a materi

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In a building, materials with a high thermal mass value include a concrete slab wit

tiled floor, brick, stone or earthen walls, or even water tanks. When positioned

correctly inside the house, thermal mass can store heat during the day in winter, an

radiate it at night time. During summer the thermal mass is protected from direct so

radiation and can act as a heat sink in hot weather to give cooler indoor temperatur

Insulation is vital to maintain even temperatures in a passive solar home. Insulation

keeps warmth inside the house in cold weather, and prevents heat from entering wh

is hot. There are many types of insulation available today to suit a wide range of ne

Windows are also an important consideration. If a house is well sealed with an

insulated ceiling and walls, then the windows will be the weak point for heat transf

and out of the house. In climates that experience cold weather, large north facing

windows are required to allow the winter sun in during cold weather, and naturally

their value will be diminished if they then allow that day's heat to escape. Close fit

heavy curtains or blinds with a pelmet will reduce heat transfer. Double glazing wi

reduce heat transfer by a similar amount to effective curtains, but will be more

expensive. There are now readily available double glazing films that are cheap and

to apply to most existing windows. Minimising the size and number of windows w

also help to reduce heat loss.

House layout

The optimum passive solar house design will always be dependent on the site wher

is to be built. However, it is generally advised to position the living rooms to the n

and bedrooms to the south. This approach maximises the benefits of the sun’s warm

in the rooms where most time is spent during the day.

Landscaping

Plants can be used effectively around the home to reduce energy consumption.

Deciduous trees planted on the north side of the home will block the sun’s light du

the hotter months and lose their leaves during the cooler months, allowing sunlight

 penetrate. The effect of features like brick pavers near the home should also be

considered, as these may radiate heat into the home during summer.

Lighting

Passive solar houses also make the most of sunlight to reduce the need for artificialighting. Skylights and clerestory windows can be positioned to provide natural lig

during the day, though these need to be well designed. Poorly designed and positio

skylights are subject to a substantial winter heat loss and summer heat gain that ma

exceed any lighting energy savings.

But I’ve already built my house...

If you already own your own home, and it has not been designed specifially to use

sun’s energy, you may be able to make the most of its existing features (shading,

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curtains and windows), or renovate using passive solar design principles. The follo

questions may help you to think about the possibilities for passive solar renovation

your home:

  Do you have north facing walls exposed to the sun where windows could be

installed?

  Do you have north facing windows that are not protected by blinds or eaves

  Do you have rooms where clerestory windows could reduce the need for ele

lighting during the day?  Could any planned extensions incorporate thermal mass (a concrete slab flo

internal brick walls etc) to help regulate temperature?

  Could insulation be added to the ceiling, walls, or under-floor to help keep

coolness or warmth in the house?

  Could gaps in window and door frames be sealed to help control the house’

temperature?

Rating your home’s energy efficiency

Designing the most energy efficient house for your site and budget is a complex process. However, there are now several computer programs designed to help mak

task easier.

Most states in Australia now have home energy rating computer software adapted

their specific climatic conditions. This software is based on NatHERS, Australia's

 National Home Energy Rating Scheme. This software can be used to make house

designs more energy efficient, and change the house’s rating according to variable

orientation, window size and position, and the type of building materials used. Som

architects will use NatHERS software when designing energy efficient houses, and

some state government energy agencies offer NatHERS assessment services for a f

 NatHERS software and energy rating schemes go by different names in different s

and other similar or related software exists which is used in certain states. Some

examples are BERS in Queensland, First Rate in Victoria, and ACTHERS in the A

What will it cost?

Many aspects of designing an energy efficient passive solar house relate to basic

design, not expensive specialised technologies. For example, a passive solar house

have as many windows as an inefficient house, but they will be positioned to optim

heat and light from the sun. Many materials that add to the efficiency of the house,

extra insulation, may add a little to the initial cost, but will lead to reduced heatingcooling costs that will pay back the extra investment. Higher cost items, like doubl

glazed windows will have longer payback periods, so their cost should be weighed

against alternatives like heavy curtains and pelmets on single glazed windows.

The cost of passive solar renovations will vary greatly depending on what is possib

your house, but if done properly will lead to a house that is more livable, uses less

energy, and contributes less to the greenhouse effect.

Case studies

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A passive solar house in southern Australia 

Further links

  Reducing your household’s greenhouse gas emissions: Global Warming, C

It! 

For further information please email renewweb@greenhouse.gov.au

 

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