“Glazing is the weak point in the thermal envelope if you’re using standard glass and a standard frame like aluminium.”
Wheeler says a good rule of thumb to follow is to have windows making up no more than 25 per cent of the total floor area of the house, and to place them carefully.
“Once you go beyond that 25 per cent there will be a heat exchange through that house that no amount of insulation in the walls and roof will compensate for,” he says. “You need to look at position, orientation, size and how the windows open. And if you’re going to glaze more than 25 per cent, upgrade your glass.”
Australian Window Association CEO Tracey Gramlick says 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, so it’s well worth investing in energy-efficient windows.
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