Passive design reduces or eliminates the need for auxiliary heating or cooling, which accounts for about 40% (or much more in some climates) of energy use in the average Australian home.
The importance of passive design cannot be overstated. Paying attention to the principles of good passive design suitable for your climate effectively ‘locks in’ thermal comfort, low heating and cooling bills, and reduced greenhouse gas emissions for the life span of your home.
Passive design utilises natural sources of heating and cooling, such as the sun and cooling breezes. It is achieved by appropriately orientating your building on its site and carefully designing the building envelope (roof, walls, windows and floors of a home). Well-designed building envelopes minimise unwanted heat gain and loss.
The most economical time to achieve good passive design in a home is when initially designing and building it. However, substantial renovations to an existing home can also offer a cost-effective opportunity to upgrade thermal comfort — even small upgrades can deliver significant improvements. If you’re buying a new home or apartment, assess its prospects for thermal comfort and/or ability to be cost effectively upgraded to reflect good passive design principles in its climate.
For best results, ‘passive’ homes need ‘active’ users — people with a basic understanding of how the home performs with the daily and seasonal climate, such as when to open or close windows, and how to operate adjustable shading.
There are several different and interrelated strategies contribute to good passive design including:
- Design for Climate
- Passive Solar Heating
- Passive Cooling
- Thermal Mass
Design for climate
Good passive design ensures that the occupants remain thermally comfortable with minimal auxiliary heating or cooling in the climate where they are built. Each of the eight main climate zones in Australia has its own climatic characteristics that determine the most appropriate design objectives and design responses.
Identifying your own climate zone and gaining an understanding of the principles of thermal comfort helps you make informed design choices for your home.
The Nationwide House Energy Rating Scheme (NatHERS), with its star classifications, is an additional and useful resource.