There are three main ways heat can be transferred into homes:
Radiation: heat that travels from a heat source to warm a surface, e.g. sun radiation shining through a window heating the floor and furniture.
Conduction: heat transferred through solid objects, e.g. heat being transferred from the outside surface of a block (the outside of the home), to the inside surface of a block (the inside of the home).
Convection: heat carried by the circulation of fluids, the circulation continues until the temperature evens out, e.g. when hot air in a room rises, drawing cooler air from below.
Heat energy is transferred from homes by conduction through the walls, floor, roof and windows. It is also transferred from homes by convection. For example, cold air can enter the house through gaps in doors and windows, and convection currents can transfer heat energy in the loft to the roof tiles. Heat energy also leaves the house by radiation through the walls, roof and windows.
Heat is lost through:
the roof – fit loft insulation
windows – fit double glazing and curtains
gaps around the door – fit draught excluders
the walls – fit cavity wall insulation
the floor – fit a carpet
Ways to reduce heat loss
There are some simple ways to reduce heat loss, including fitting carpets, curtains and draught excluders.
Heat loss through windows can be reduced using double glazing. There may be air or a vacuum between the two panes of glass. Air is a poor conductor of heat, while a vacuum can only transfer heat energy by radiation.
Heat loss through walls can be reduced using cavity wall insulation. This involves blowing insulating material into the gap between the brick and the inside wall, which reduces the heat loss by conduction. The material also prevents air circulating inside the cavity, therefore reducing heat loss by convection.
Heat loss through the roof can be reduced by laying loft insulation. This works in a similar way to cavity wall insulation.