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4.2 DESIGN FOR CLIMATE
This fact sheet provides an introductory guide to key passive design responses for each main climate zone in Australia. This is a simplified overview only and should be used in conjunction with more detailed information presented in subsequent fact sheets.
An explanation of the conditions required for human thermal comfort and how our bodies achieve it is included at the end of this fact sheet.
This fact sheet will guide you in choosing the passive design features most appropriate for your needs, site and climate.
| ZONE | DESCRIPTION |
|---|---|
| 1 | High humid summer, warm winter |
| 2 | Warm humid summer, mild winter |
| 3 | Hot dry summer, warm winter |
| 4 | Hot dry summer, cool winter |
| 5 | Warm temperate |
| 6 | Mild temperate |
| 7 | Cool temperate |
| 8 | Alpine |
AUSTRALIAN CLIMATE ZONES
Australia’s broad range of climatic conditions have been grouped into eight zones, for simplicity. The main characteristics affecting envelope design for human comfort have been listed for each zone along with key responses.
Choose the climate zone for your site from the map and refer to the appropriate section for an overview of the climate and how to respond to it in passive design terms.
The BCA defines eight climate zones for thermal design within Australia. The designer or builder should be aware that the design and construction requirements of single dwellings differ for each climate zone.
There are many definitions of Australian climate zones. The zones used in this guide are defined by the Building Code of Australia.
Use this overview, and the highlighted references to other fact sheets to access more detailed information as you proceed through the various stages of designing, purchasing or altering your home.
| ZONE 1 |
| High humid summer, warm winter |
 |
Main characteristics:
Highly humid with a degree of ‘dry season’.
High temperatures year round.
Minimum seasonal temperature variation.
Lowest diurnal (day/night) temperature range.
Key design responses:
Employ lightweight (low mass) construction.
Maximise external wall areas (plans with one room depth are ideal) to encourage movement of breezes through the building (cross ventilation).
[See: 4.6 Passive Cooling]
Ceiling fans should be used where required.
Site for exposure to breezes and shading all year.
[See: 4.3 Orientation]
Shade whole building summer and winter (consider using a fly roof).
[See: 4.4 Shading]
Use reflective insulation and vapour barriers.
[See: 4.7 Insulation]
Ventilate roof spaces.
Use bulk insulation if mechanically cooling.
[See: 4.6 Passive Cooling]
Choose light coloured roof and wall materials.
Elevate building to permit airflow beneath floors.
Consider high or raked ceilings.
Provide screened, shaded outdoor living areas.
Consider creating sleepout spaces.
Design and build for cyclonic conditions.
| ZONE 2 |
| Warm humid summer, mild winter |
 |
Main characteristics:
High humidity with a definite ‘dry season’.
Hot to very hot summers with mild winters.
Distinct summer/winter seasons.
Moderate to low diurnal (day/night) temperature range. This can vary significantly between regions eg inland to coastal.
Key design responses:
Use lightweight construction where diurnal (day/night) temperature range is low and include thermal mass where diurnal range is significant.
[See: 4.9 Thermal Mass]
Maximise external wall areas (plans ideally one room deep) to encourage movement of breezes through the building (cross ventilation).
[See: 4.6 Passive Cooling]
Site for exposure to breezes.
[See: 4.3 Orientation]
Evaporative cooling or ceiling fans should be used if required.
Shade whole building where possible in summer.
[See: 4.4 Shading]
Allow passive solar access in winter months only.
Shade all east and west walls and glass year round.
Avoid auxiliary heating as it is unnecessary with good design.
Use reflective and bulk insulation (especially if the house is air-conditioned) and vapour barriers.
[See: 4.7 Insulation]
Use elevated construction with enclosed floor space, where exposed to breezes.
Choose light coloured roof and wall materials
Provide screened and shaded outdoor living.
| ZONE 3 |
| Hot dry summer, warm winter |
 |
Main characteristics:
Distinct wet and dry seasons.
Low rainfall and low humidity.
No extreme cold but can be cool in winter.
Hot to very hot summers common.
Significant diurnal (day/night) range.
Key design responses:
Use passive solar design with insulated thermal mass.
[See: 4.9 Thermal Mass]
Maximise cross ventilation.
[See: 4.6 Passive Cooling]
Evaporative cooling or ceiling fans should be used if required.
Consider convective (stack) ventilation, which vents rising hot air while drawing in cooler air.
Site home for solar access and exposure to cooling breezes.
[See: 4.3 Orientation]
Shade all east and west glass in summer.
[See: 4.4 Shading]
Install reflective insulation to keep out heat in summer.
[See: 4.7 Insulation]
Use bulk insulation in ceilings and walls.
Build screened, shaded summer outdoor living areas that allow winter sun penetration.
Use garden ponds and water features to provide evaporative cooling.
| ZONE 4 |
| Hot dry summer, cool winter |
 |
Main characteristics:
Distinct seasons with low humidity all year round.
High diurnal (day/night) temperature range.
Low rainfall.
Very hot summers common with hot, dry winds.
Cool winters with cold dry winds.
Key design responses:
Use passive solar principles with well insulated thermal mass.
[See: 4.5 Passive Solar Heating; 4.9 Thermal Mass]
Maximise night time cooling in summer.
[See: 4.6 Passive Cooling]
Consider convective (stack) ventilation, which vents rising hot air while drawing in cooler air.
Build more compact shaped buildings with good cross ventilation for summer.
Maximise solar access, exposure to cooling breezes and cool air drainage. Protect from strong, cold winter and dusty summer winds.
[See: 4.3 Orientation]
Shade all east and west glass in summer.
[See: 4.4 Shading]
Provide shaded outdoor living areas.
Consider adjustable shading to control solar access.
Auxiliary heating may be required.
[See: 6.6 Renewable Energy]
Use evaporative cooling if required.
Avoid air-conditioning.
[See: 6.2 Heating and Cooling]
Use reflective insulation to keep out summer heat.
[See: 4.7 Insulation]
Use bulk insulation for ceilings, walls and exposed floors.
Consider double glazing.
Use ponds and water in shaded courtyards to provide evaporative cooling.
Draught seal thoroughly. Use airlocks to entries.
| ZONE 5 |
| Warm temperate |
 |
Main characteristics:
Low diurnal (day/night) temperature range near coast to high diurnal range inland.
Four distinct seasons. Summer and winter can exceed human comfort range. Spring and autumn are ideal for human comfort.
Mild winters with low humidity.
Hot to very hot summers with moderate humidity.
Key design responses:
Use passive solar principles.
[See: 4.5 Passive Solar Heating; 4.6 Passive Cooling]
Use insulated thermal mass.
[See: 4.9 Thermal Mass]
Use high insulation levels.
[See: 4.7 Insulation]
Maximise solar access in winter.
[See: 4.5 Passive Solar Heating]
Minimise all east and west glazing. Use adjustable shading.
[See: 4.4 Shading]
Use double glazing to insulate windows.
[See: 4.10 Glazing]
Minimise east and west wall areas.
Use cross ventilation and passive cooling in summer.
[See: 4.6 Passive Cooling]
Use convective ventilation and circulation.
Site homes for solar access and exposure to cooling breezes.
Draught seal and use airlock entries.
No auxiliary heating or cooling is required in these climates with good design.
Use reflective insulation for summer heat.
Use bulk insulation to walls, ceilings and exposed floors.
| ZONE 6 |
| Mild temperate |
 |
Main characteristics:
Low diurnal (day/night) temperature range near coast to high diurnal range inland.
Four distinct seasons. Summer and winter can exceed human comfort range. Spring and autumn are ideal for human comfort.
Mild to cool winters with low humidity.
Hot to very hot summers, moderate humidity.
Key design responses:
Use passive solar principles.
[See: 4.5 Passive Solar Heating; 4.6 Passive Cooling]
High thermal mass solutions are recommended.
[See: 4.9 Thermal Mass]
Use high insulation levels, especially to thermal mass.
[See: 4.7 Insulation]
Maximise north facing walls and glazing, especially in living areas with passive solar access.
[See: 4.3 Orientation]
Minimise all east and west glazing.
Use adjustable shading.
[See: 4.4 Shading]
Use double glazing and heavy drapes with sealed pelmets to insulate windows.
Minimise external wall areas (especially east and west).
Use cross ventilation and passive cooling in summer.
[See: 4.6 Passive Cooling]
Use convective ventilation and heat circulation.
Site new homes for solar access, exposure to cooling breezes and protection from cold winds.
Draught seal thoroughly and use entry airlocks.
No auxiliary heating or cooling is required in these climates with good design.
Use reflective insulation to keep out summer heat.
Use bulk insulation to walls, ceilings and exposed floors.
| ZONE 7 |
| Cool Temperate |
 |
Main characteristics:
Low humidity, high diurnal range.
Four distinct seasons. Summer and winter exceed human comfort range, variable spring and autumn conditions.
Cold to very cold winters with majority of rainfall.
Hot dry summers.
Key design responses:
Use passive solar principles.
[See: 4.5 Passive Solar Heating]
High thermal mass is strongly recommended.
[See: 4.9 Thermal Mass]
Insulate thermal mass including slab edges.
[See: 4.7 Insulation]
Maximise north facing walls and glazing, especially in living areas with passive solar access.
Minimise east, west and south facing glazing.
Use adjustable shading.
[See: 4.4 Shading]
Use double glazing, insulating frames and/or heavy drapes with sealed pelmets to insulate glass in winter.
Minimise external wall areas (especially east and west).
Use cross ventilation and night time cooling in summer.
[See: 4.6 Passive Cooling]
Site new homes for solar access, exposure to cooling breezes and protection from cold winds.
[See: 4.3 Orientation]
Draught seal thoroughly and provide airlocks to entries.
Install auxiliary heating in extreme climates. Use renewable energy sources.
[See: 6.2 Heating and Cooling; 6.6 Renewable Energy]
Use reflective insulation to keep out heat in summer.
Use bulk insulation to keep heat in during winter. Bulk insulate walls, ceilings and exposed floors.
| ZONE 8 |
| Alpine |
 |
Main characteristics:
Low humidity, high diurnal range.
Four distinct seasons. Winter can exceed human comfort range.
Cold to very cold winters with majority of rainfall. Some snowfall.
Warm to hot, dry summers, variable spring and autumn conditions.
Key design responses:
Use passive solar principles.
[See: 4.5 Passive Solar Heating]
High thermal mass is recommended but must be well insulated.
[See: 4.9 Thermal Mass]
Use high levels of insulation.
[See: 4.7 Insulation]
Insulate thermal mass including slab edges.
Maximise north facing walls and glazing, especially in living areas with passive solar access.
Minimise east, west and south facing glazing.
Use adjustable shading.
[See: 4.4 Shading]
Use double glazing and insulating frames. Augment with heavy drapes and pelmets.
Minimise external wall areas.
Use night time cooling in summer.
[See: 4.6 Passive Cooling]
Use convective ventilation and circulation.
Site homes for solar access and protection from cold winds.
[See: 4.3 Orientation]
Draught seal thoroughly and airlock entries.
Auxiliary heating may be required.
[See: 6.2 Heating and Cooling]
Use reflective insulation to keep out summer heat.
[See: 4.7 Insulation]
Use bulk insulation to walls, ceilings and exposed floors.
CLIMATE SENSITIVE DESIGN
The importance of climate sensitive design can not be overrated.
Eaveless cold climate designs (borrowed from Europe) do not work in Australia |
Many homes are built without eaves to save as little as $2,500. Builders may then add an air conditioner to counteract the overheating effects of the sun. This environmental burden can easily be avoided.
Homeowners pay hundreds of dollars more than they need to each year in heating and/or cooling bills because they are not taking advantage of free heating and cooling from passive design.
HUMAN THERMAL COMFORT
The main factors influencing human comfort are:
- Temperature.
- Humidity.
- Air movement (breeze or draught).
- Exposure to radiant heat sources.
- Cool surfaces to radiate for cooling.
Sound building envelope design will moderate all of these factors except humidity.
To do this effectively, envelope design should be varied to suit the climate. It can significantly improve comfort levels whilst reducing heating and cooling bills.
Humans are comfortable only within a very narrow range of conditions. Human body temperature must remain at a constant 36.9°C. The body generates heat – even while at rest. We must lose heat at the same rate as it is produced or gain heat at the same rate it is lost. The diagram below shows the various ways by which our bodies achieve this.
Losing body heat
We mainly lose heat through the evaporation of perspiration. High humidity levels reduce evaporation rates. When relative humidity exceeds 60 per cent, our ability to cool is greatly reduced.
Evaporation rates are also influenced by air movement. Generally, a breeze of 0.5m per second provides a one off comfort benefit equivalent to a 3°C temperature reduction.
We also lose heat by radiating to surfaces cooler than our body temperature. The greater the temperature difference, the more we radiate. Whilst not our main means of losing heat, radiation rates are very important to our perception of comfort.
Gaining body heat
When the heat produced by our bodies is insufficient to maintain body temperature, we insulate by putting on more clothes, shelter from wind and draughts, or shiver (increasing the production of body heat).
This is because we generate most of the heat required from within. A secondary source of heat gain is radiation. As with cooling, radiation is very important to our perception of comfort.
BUILDING THERMAL COMFORT
Thermal comfort rating (or building envelope performance) tools are computer programs that model the amount of heating and cooling energy required to maintain comfortable temperatures in a building. They take into account climate, season and envelope design.
[See 1.5 Rating Tools]
A thermal comfort rating only reveals the energy performance of a building’s design and fabric. It does not measure other areas of energy consumption (eg appliance efficiency, transport and embodied energy).
In warmer climates, these variables can account for more energy consumption during the lifespan of your home than the performance of the envelope.
| ADDITIONAL READING |
|---|
| Contact your State / Territory government or local council for further information on passive design considerations for your climate. www.gov.au |
| Australian Bureau of Meteorology www.bom.gov.au/climate/environ/design/design.shtml |
| BEDP Environment Design Guide DES 20 Arid Climates and Enhanced Natural Ventilation. GEN 12 Residential Passive Solar Design. |
| Commonwealth of Australia, Australian Model Code for Residential Development (AMCORD) (1995), AGPS Canberra. |
| Hollo, N. (1997), Warm House Cool House: Inspirational designs for low-energy housing, Choice Books, Australia. |
| Wrigley, Derek (2004), Making Your Home Sustainable: A Guide to Retrofitting, Scribe, Carlton North, Victoria. |
Principal Author:
Chris Reardon
Contributing Author:
Paul Downton