Double glazing buyers guide

Looking out

ReNew takes a look at window and door glass insulating options to help you make the best choice.

Windows often make or break the look of a home, but there’s a lot more to them than aesthetics. The importance of reducing heat flows through windows and doors should not be overlooked. A great deal of heat can flow through single pane glass, and an otherwise well-insulated house can suffer considerable heat transfer. In fact, a single pane plain glass window is not much better than a hole in the wall when it comes to its insulating ability.

There are two main problems. Firstly, heat is lost by direct radiation—warm objects inside the room radiate heat, which passes straight through the window glass to the outside.

Secondly, warm air is rapidly cooled against the glass, falling to the floor to be replaced by more warm air. This is called a convective current and it can literally suck heat out of a room as fast as you can add it. For example, if you have ducted heating, the outlets are often directly under or above the windows—this dramatically increases heat loss by increasing the temperature differential and breaking up the air layer on the inside of the window. Installing deflectors on the heating vents (around $10 each) deflects the hot air away from the window, saving up to 20% on heating costs.

Insulate those windows
Windows can be insulated in a number of ways. Covering them with thick curtains or using roller or vertical blinds is a good place to start, but they must have pelmets at the top to prevent convective currents circulating, otherwise they will do very little. However, this means that the windows are only insulated when you can’t see out of them, so you can have a well-insulated house, or enjoy your view, but not both. If you find pelmets ugly or impractical, then you may be able to fit a strip of wood or other material between the top of the window frame and the curtain rail or track.

Pleated blinds (such as the double layered Luxaflex Duettes) can seal well at the top because they can be mounted against the window frame.
External roller shutters are an alternative to curtains or blinds, but they also have the problem that once in place, they let in no light.

The ideal solution is to improve the insulating properties of the glass itself.

Read the full article in ReNew 115

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