Healthy Homes Self Assessment Online Check

Window insulation: The heat loss from windows can account for 40% or more of the total heat lost in a typical, otherwise reasonably well insulated home. Once ceilings and floors are insulated, windows are usually the weakest part of the thermal envelope.

HomeFit requires homes to have either good curtains (see info tab below for definition) or double glazing in the living room and bedrooms.

Do all the windows in the living spaces and bedrooms have either 'good' curtains and/or double glazing?

Yes No

Windows - what to look for

'Good' means that curtains are:

floor-length and touch the floor, or have pelmets above them or close-fitting tracks with only a minimal airgap between the top of the curtain and the wall (sill-length curtains are less effective)
fitted tightly against the wall or window frame
wider than the window frame
double layer

'Good' blinds must have a snug fit with the window frame, creating a good seal to trap the air in the gap between them and the window. Roman blinds and pleated (cellular, or honeycomb) blinds are often good; roller, wooden and Venetian blinds are usually not.

Double glazing works by creating an insulating layer of gas between two panes of glass.

Retrofit double glazing is still quite expensive in New Zealand so it's worth repeating that it's not required in HomeFit as long as the home has 'good' curtains. However, double glazing is very effective at reducing heat lost through windows and will make the home significantly more comfortable. Consider retrofitting when carrying out a major refurbishment or replacing windows.

These 'good' curtains are full length, touch the walls and floor and are double layered.

These curtains are too short and are not "closed" at the top, because of the rail they are hanging from. This means that cold air will fall from the window and cause draughts.

This roller blind hangs away from the window so loses heat around the sides.

These cellular or "honeycomb" blinds are effective at keeping in warmth. They hang very close to all four sides of the window frame and their cells trap air = insulation.

Double glazing has an inner and outer pane of glass separated by a small gap. Single glazing has only one piece of glass. Look at the edge of the window - double glazing has an obvious gap between the two panes.

Why having window insulation is important

Double glazing and curtains operate in the same way; by creating still air spaces that act like insulation. Double glazing is now required under the New Zealand Building Code for new homes and in many cases costs no more than single glazing to install. It can still be reasonably expensive to retrofit to existing homes, so we offer it as an alternative to good curtains to show better window performance in HomeFit, and if you have both you are more likely to get HomeFit PLUS.