Windows lose heat through draughts, and direct heat loss through the glass. Both can be significantly reduced with double glazing. But don’t rush to replace your windows with new plastic frames just yet. If your window frames are in good condition, think about improving the windows you’ve got.
First, if your windows are draughty, look at using draught excluders that can be found in any good DIY shop.
Next, a quick and cheap improvement for windows is a secondary glazing film – much like cling film. This is stuck to the inside of the window frame using a double-sided tape. The film is then gently heated with a hairdryer to shrink it, leaving a clear, wrinkle free surface. This is very effective. There air trapped between the film and the glass provides a barrier to direct heat loss. Depending on how it is fitted, you may not be able to open the treated windows, but the film is very easily removed. Kits can be found in most DIY shops.
The next step is full secondary double glazing.
If your house is a listed building, or in a conservation area, you will need planning permission to replace windows – which is by no means certain. In this case, secondary double glazing, fitted inside the existing windows, may be the only option.
In any case, if your windows are in good condition, you should consider secondary glazing anyway. It is much cheaper and less disruptive than full re-glazing.
Secondary double-glazing works by installing a second glazing pane inside the original. This is usually a high-quality plastic as opposed to glass (plastic is lighter making it easier to fit to existing frames without reinforcement). The fitting is sometimes with a plastic section screwed onto the frame, or sometimes with self-adhesive magnets. The second option makes the panes easy to remove for cleaning.
There are a few do it yourself secondary glazing kits on the market. You measure your windows and order the kit. It comes ready to fit.
Or, if you prefer, there are companies that will provide a complete service – measure, make and fit.
Secondary glazing is only half as effective as modern double glazing, but much less expensive.