GreenTips

The first consideration when selecting a window system is its energy performance. Heat loss through the window during its life is likely to have a much greater environmental impact than any environmental impact resulting from its production. The window efficiency rating scheme has been established to provide information on the thermal performance of different window systems. In many cases, double glazing low-e timber framed windows will provide excellent insulation levels.

Most window systems can be sourced in either single or double glazed versions. Triple glazing is available overseas, but is not readily available in NZ.

The heat loss of double glazed units can be further improved with an inert gas fill or radiant film that is designed to reflect heat back into the room.

In commercial buildings keeping solar gains out is often more important than keeping heat in. For this reason, glazing systems can be tinted with reflective films or tinted glass to reduce the unwanted gains.

Window systems can often leak heat out through the frames. This is often characterised by condensation on the frames. Some systems (such as timber windows), are naturally well insulated, whereas others such as steel and aluminium will need to incorporate thermal breaks.

When selecting frames with wooden components, ensure that the timber is from a sustainable resource. (See our timber information page.) Aluminium and steel frames are available with a high recycled content.

Further information is available on aluminium, steel window systems, and advanced façade systems.

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