If you can't install double glazing - for example if you live in a conservation area, period property, or listed building - you can install secondary glazing, use heavy curtains, or do both.
A secondary pane of glass and frame can be fitted inside the existing window reveal. This won't be as well sealed as a double-glazing unit, but will be much cheaper to fit, and will still save energy - you could save about £100 a year on fuel bills. Low emissivity glass will improve the performance of secondary glazing.
Secondary glazing kits are available for the proficient DIYer to install themselves - these cuts down on costs and are a non-intrusive way of insulating your windows.
Heavy curtains, sealed blinds and shutters
Curtains lined with a layer of heavy material can reduce heat loss from a room through the window at night and cut draughts. Hollow blinds, fitted into place with a sealed frame, and sealed shutters will also help cut draughts and keep your heat in for longer.
Installing energy-efficient glazing
Before installing double glazing, check with your local planning office if you:
Most people will have double glazing fitted professionally.