Windows and doors

Windows do not usually account for much heat loss, approximately 5 - 10%, but their manufacture can be very energy intensive. The light that they bring into buildings can be used to help heat buildings



The choice in window frames is really limited to aluminium, wood or uPVC.

uPVC has a very high embodied energy and is also linked to large scale pollution in the manufacturing process. They are also not easily recyclable.

Wood can be long lasting, is environmentally friendly and a good insulator.

Aluminium is not a good insulator and has a very high embodied energy rating but can be easily recycled.


Single glaze windows are not good insulators, so using double or even triple glazed units can save a lot of heat energy being wasted. There are also different types of glass that have better insulation properties than others.


Doors like windows are not responsible for a great deal of heat loss on their own, but the draughts associated with them can be - up to 15%. So design is important to minimise this waste. This can be achieved by creating lobbies around external doors to create an additional barrier to draughts. Where this is not possible simple draught proofing methods can still cut heat loss dramatically.

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