High-performing windows

Issue 20 Words: Sarah Robertson

What makes windows and other double glazing units high-achievers in your home?

Windows are possibly the most complex elements in a home, says Tracey Gramlick, executive director of the Australian Window Association (AWA). Windows are connection points between our inside and outside worlds; and importantly, they let in natural light, heat and fresh air.

Choosing energy efficient windows will make your home more comfortable, can reduce energy costs and help to create a brighter, cleaner and healthier home environment. Windows expert Dr Peter Lyons, of Peter Lyons & Associates, says that at a time when modern materials enable us to create efficient buildings, the spotlight has shifted to windows as “the weak link”. Windows can have an enormous effect on heating and cooling a house. The AWA estimates up to 40 per cent of a home’s heating energy can be lost through windows and up to 87 per cent of its heat gained through them. Choosing high-performing windows and placing them appropriately can reduce energy costs significantly and improve thermal comfort. The art is in knowing how different windows, whether you choose double glazing, low-e-coated single-glazed units, timber or aluminium frames, will interact with the design of your home.

There are a large range of window systems available in Australia, from single to double-glazed and triple-glazed units with aluminium, timber, uPVC, composite and other frames, argon gas fills, low-e coatings and more. If you know the basics of the heating and cooling impacts of windows, rely on rating systems and experts to guide your decision and weigh up price and visual amenity, you can find a window system to suit and keep your home performing effectively.


One of the first things to know about windows is that their performance doesn’t depend solely on the number of glazing layers (such as double glazing), but also on whether the glass is tinted or coated, plus the type of frame, climate and the window’s orientation. On top of these considerations, a home’s comfort level will be influenced by design factors such as how much glazing it has, whether it is shaded, how much heat can be captured by thermal mass and whether heat can be vented out when necessary.


For homeowners, the Window Energy Rating Scheme (WERS) is a good starting point on windows that might best meet your needs.


Climate and orientation are vital when determining the performance of windows in your home. The Building Code of Australia simplifies Australia’s climate zones to just eight, but home energy rating schemes currently divide Australia into 69 different zones, and this is soon to be increased to 80. As well, the impact of a window on a house’s annual energy load depends on its orientation, as well as factors such as thermal mass.


WERS – http://www.wers.net/wers-home


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Cover of Issue 20
You can read more about High-performing windows in Issue 20 of Sanctuary magazine.

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