A three bedroom semi detached house with no insulation costs more
than three times as much to heat as an energy-efficient house with
full insulation and a modern boiler. It can lose up to 75% of heat
through the roof, walls, windows, floors and doors.
Heat can be lost around ill-fitting doors and windows. Insulation will help to retain
the heat in winter and also helps to keep the house cool during a very
hot summer.