Windows are critical to the overall energy efficiency of a home – as much as 40% of the heat lost from a home is lost from windows and up to 50% of unwanted heat gain is through the windows.
Window Energy Rating Scheme (WERS)
This scheme provides an independent, unbiased star rating for residential windows based on their energy performance. Rated windows carry a sticker that certifies their winter and summer energy efficiency, as well as their ability to provide furnishings with protection from fading. For each of these three categories, a number of stars from one to five is given – the more stars, the better the performance.
For more information on the Window Energy Rating Scheme, visit www.wers.net.
Preventing Winter Heat Loss
Appropriate window selection and protection can reduce heat loss through windows by up to 70% and save you around $200 each year in reduced heat loss and up to $500 per year if heating and cooling are taken into account.
There are a number of ways this can be achieved:
Installing double glazed windows, which consist of two panes of glass separated by a sealed air space typically between 6mm and 20mm wide. Double glazing reduces heat loss by up to 64% more than a single glazed window while still allowing natural light and views, and decreases noise transmission. A cheaper alternative is double glazing 'film' which is fitted to the frame of an existing window, creating an air space between the film and the glass. This should last two seasons.
Installing Low-E glass (low emissivity glass), which has an invisible coating that reflects radiant heat back into the room (generally only available in double gazed windows). Improves performance by up to 38% over conventional double glazing.
Hanging closely-woven, close-fitting curtains with boxed pelmets or solid strips above the curtain rail.
Using tightly fitting Holland or Roman type blinds with closely woven fabrics.
Installing insulated shutters on the inside or outside of a window which fit tightly against the window frame.