‘Passive design’ is design that works with the local climate to maintain a comfortable temperature in the home. Good passive design should reduce or eliminate the need for additional heating or cooling depending on your location and often relies on an active occupant to work properly. A passively designed home can deliver a lifetime of thermal comfort, low energy bills, and low greenhouse gas emissions.
With passive design, building features such as orientation, thermal mass, insulation and glazing work together to take advantage of natural sources of heating and cooling, such as sun and breezes, and to minimise unwanted heat gain and loss. It is best to use passive design principles when designing or building a new home, but many features of passive design can be added through renovations or simple home improvements.
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Australia has 8 main climate zones (as specified by the National Construction Code), and it is important to make sure your home is designed to suit your climate zone. Different passive design strategies suit different climates.
Passive solar heating lets in winter sun and ensures that the building envelope keeps heat inside. It must be matched by careful design and management of summer heat in many climates.
Passive cooling techniques cool both the house and the people in it, using elements such as air movement, evaporative cooling and thermal mass.
Orientation is the way you place your home on its site to take advantage of the sun and the prevailing winds in your location. Good orientation can significantly improve comfort and reduce your heating and cooling needs.
Thermal mass is the ability of a material to absorb and store heat energy. Appropriate use of thermal mass in your home can save significantly on heating and cooling costs.
Insulation acts as a barrier to heat flow and is essential for keeping your home warm in winter and cool in summer. Some types of insulation can also help with weatherproofing and soundproofing.
Glazed windows and doors have a significant effect on your home’s thermal performance – up to 40% of a home’s heating energy can be lost and up to 87% gained through glazing. Choose the right glazing for your climate and orientation.
Appropriate shading — which can include eaves, awnings, shutters, and plantings — can maximise thermal comfort by allowing in winter sun but blocking summer rays. The most appropriate strategy will differ with climate and orientation.
Skylights are a good source of natural light, and careful choice and placement can minimise any contribution to glare or heat gain.
Ventilation with fresh air is essential for a healthy home, but it should be controlled rather than through unwanted air leaks. Sealing your home is one of the simplest upgrades you can make to increase your comfort and reduce energy costs.
Condensation in a home can cause rot and mould. With a more airtight home, you must pay more attention to appropriate building membranes and management of ventilation.
‘Passive House’ is a design standard developed in Germany that aims to achieve high levels of thermal comfort and energy efficiency with insulation, airtightness, window and door design, and heat recovery ventilation systems.