Heat rises, so the majority of heat from a home is lost through the roof.
Loft insulation helps to prevent this problem by adding an insulating layer between the roof of the house and the heat-producing rooms. This layer of insulation prevents the rising heat from escaping out of the roof. This can reduce heating bills by up to 20%, as less energy is required to keep the house warm.
The latest recommendation by the Energy Savings Trust for depth of loft insulation is 300mm, or 12 inches.