General information drawn from Your Home and energy.gov.au, not design advice for a particular house. The official places to check are Your Home and the Bureau of Meteorology’s local climate data.
The zone descriptions Your Home uses place parts of Western Australia in five of Australia’s eight building climate zones, from the tropical north at Exmouth to the mild south coast at Albany. Each zone asks something different of cooling, and official advice for one does not carry over to the next.
Where the zones fall in WA
Your Home explains that the eight zones come from the National Construction Code, and that knowing your zone helps make sure a home suits local conditions. This table lists only the WA places the zone descriptions name, so it is a selection, not the full text.
| Zone | Description | WA places named |
|---|---|---|
| 1 | Hot humid summer, warm winter | Northern Australia from Exmouth |
| 3 | Hot dry summer, warm winter | From Carnarvon on the coast across the deserts; energy.gov.au also names Newman |
| 4 | Hot dry summer, cool winter | The coastal hinterland, including Yalgoo and Warburton |
| 5 | Warm temperate | The coastal strip from 27 to 34 degrees south, including Geraldton, Perth and Bunbury; coastal strips around Esperance and Eucla |
| 6 | Mild temperate | The southern coast and hinterland around Albany |
Inside each zone are many smaller subzones, shaped by things like wind patterns and height above sea level, and Your Home says those local conditions matter too. For a finer reading, the Nationwide House Energy Rating Scheme uses 69 local climate zones, which you can look up by postcode, and the Bureau of Meteorology keeps climate data for local areas.
The north: cooling without heating
Your Home’s passive cooling guidance treats the hot humid climate of zone 1 as one “where no heating is required”. energy.gov.au’s guide for northern Australia follows from that: “Select cooling-only units for tropical climates and reverse-cycle air conditioners for sub-tropical and hot arid climates where both heating and cooling functions are needed.” Its tropical design tips include shading such as wide eaves, window awnings and verandahs.
The hot arid zone: a case for evaporative
For zone 3, energy.gov.au describes hot, dry summers, warm winter days with cold nights, low rainfall and dry winds all year. Its tips for hot arid homes include “Invest in evaporative cooling to manage indoor comfort levels”, and its air conditioner advice adds that in hot arid climates “you may consider alternative technologies such as evaporative cooling”. The evaporative cooling guide looks at what that choice asks in return.
Inland: using the cool of the night
Zone 4’s hot dry summers come with cool winters, and inland nights can do some of the cooling work. Your Home says “Cool night air is a reliable source of cooling in inland areas where cool breezes are limited and diurnal temperature ranges usually exceed 6−8°C.” In climates where day and night differ by 6°C or more, it adds, thermal mass can also be used to cool a home. energy.gov.au’s hot arid tips point the same way: appropriate use of thermal mass such as brick walls and concrete slabs, and a light-coloured roof to reflect heat.
Perth and the south: heating as well as cooling
Zones 2 to 6 are, in Your Home’s words, “temperate and warm climates (Climate zone 2−6) where both heating and cooling are required”. That takes in Perth, Bunbury, Esperance and Albany. Your Home describes reverse-cycle air conditioners as “the most energy-efficient heater and cooler of all types, irrespective of fuel source”, which is why a system that does both jobs is worth weighing in a two-season climate. In the south, Your Home also notes that concrete slabs laid on the ground can help with passive cooling where deep earth temperatures are low, as in most of southern Australia. Perth’s coastal ally, the sea breeze, has a guide of its own.
A different map on the label
Non-ducted household air conditioners must carry the Zoned Energy Rating Label, which rates heating and cooling efficiency in three broad Australian climate zones, not the eight building zones above.
Planning for hotter years
Your Home notes that the zones reflect today’s climate, and that “heatwaves expected to become more common for all parts of Australia”. Its advice is to consider both the current and the predicted climate of your region when buying, building or renovating. WA’s Air Conditioning Rebate, covered in the rebates guide, is aimed at areas of high heat discomfort; the sources behind this guide do not list which towns those are.
energy.gov.au says to choose a correctly sized system for your local climate, house and room design, and that “It pays to get professional assistance”. A licensed installer who knows your zone can size it for your home.