There's only so much insulation your curtains can provide if your windows themselves aren't energy efficient. Single-glazed windows can leak heat from your home and make living spaces draughty even when the heating is cranked up. Swapping out single glazing for A-rated double glazing can save you between £140 and £160 on your annual heating costs, according to the Energy Saving Trust.

While upgrading your windows is usually relatively straightforward, it might not be quite so simple if your home is a protected listed building. If it's not possible to replace your windows, secondary glazing, which involves fitting a pane of glass or transparent material on the inside of an existing window, may be a more appropriate option.

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