Insulation vital for tackling heat loss

Alot of your home’s heat can escape through your windows. One way to minimise this heat loss is by providing insulation for your windows.

There are a few main types of window insulation including curtains, blinds or double glazing.

Most houses have some form of curtains or blinds on the windows.

For these to be effective they need to trap a layer of air behind them and have enough thickness to trap some air inside them, too.

Blinds are usually very thin and often don’t really seal off the air behind them. Generally they will provide very limited insulation unless they are specifically designed thermal blinds.

To provide good insulation curtains should be made from thick, thermally backed material and preferably be double layered.

Your curtains should be a tight fit against the wall and either be floor to ceiling or have pelmets on them. Closefitting thermal curtains that cover the entire width of the window, fall to the floor, and have pelmets that are installed tight against the wall can reduce the heat loss through single-glazed windows by about 60 per cent.

This applies only with the curtains drawn, and curtains are therefore not a substitute for double-glazed windows.

For double glazing, good curtains can reduce heat loss through windows by 40-50 per cent.

Having your curtains open during the day in winter and closing them just before it gets dark will help keep rooms warm.

A well designed double-glazed window with a wooden, PVC or thermally broken aluminium frame:

Can halve the heat loss through the window Significantly improves thermal comfort Reduces external noise Reduces condensation. Some double-glazing is better than other double glazing. For best performance, look for the following things:

Frames that are thermally broken, or made from an insulating material such as U-PVC or wood. These will perform better thermally than windows with standard aluminium frames. It can reduce window heat loss by between 20 per cent (thermally broken aluminium frames) and 40 per cent (PVC or wooden frames), compared to double-glazing in standard aluminium frames.

This allows light and heat in, but reflects escaping heat back to the inside. Low-e glass cuts window heat loss by about 20 per cent to 30 per cent, compared to doubleglazing without low-e.

Multiple layers of good seals to keep draughts, moisture and noise out. The joint between the glazing unit and the frame also needs to be well-sealed.

Spacers made of plastic or stainless steel to separate the glass panes (instead of aluminium) to reduce heat loss and condensation at the glass edge.

An inert gas filling (such as argon) between the glass layers. This acts as a better insulator than air, reducing window heat loss by about three to nine per cent, compared to double-glazing with air filling.

Close-fitting thermal curtains will reduce heat loss through double-glazed windows even further.