2. Using thermograms to investigate heat loss
Thermograms are useful for examining heat lost from a house, as they show the temperature distribution over its surface.
The yellow and orange roof and window areas are the warmest – these are the worst insulated parts of the house.
The dark wall areas are the coolest – these are the best insulated parts of the house.
Photo credit: Alfred Pasieka / Science Photo Library
Thermogram of a house showing the distribution of heat over its surface. The colour coding ranges from white to yellow for the warmest areas (greatest heat loss) through red to purple and green for the coolest areas (greatest insulation). This thermogram shows that the roof and windows (yellow) are poorly insulated, while the walls (red, purple and green) are losing the least heat. Thermograms are often used to check houses for heat loss, so that they can be made more energy efficient through improved insulation.
A poorly insulated house loses more energy and so costs more to heat. It also means that more pollution, particularly carbon dioxide, is created in order to heat the house.

3. Heat transfer – energy loss
Where is the most heat lost from a poorly insulated house?
roof 20%
windows 12%
Worksheet 3 accompanies this slide.
This worksheet suggests how students can investigate heat loss by attempting to insulate a shoebox.
walls 36%
doors 4%
floor 28%

4. Examining insulation What are the different types of home insulation?
insulating layer
of air
Double glazing adds an extra pane of glass to each window. This means that there is a layer of air or a vacuum between the two panes.
This helps to prevent heat loss by conduction.
side-view
of double glazing
Loft insulation is plastic foam that contains trapped air and so acts as an insulator to stop conduction of heat through the roof tiles.
Draught excluders are hairy or spongy strips which are placed under doors to prevent the movement of convection currents.

5. prevents convection currents
Examining insulation
Curtains reduce heat loss by covering up gaps around windows through which convection currents sometimes pass.
Cavity wall insulation involves placing a layer of plastic foam insulation in between two layers of outside walls. This prevents heat loss by both conduction and convection currents.
convection currents
in the cavity
foam insulation
prevents convection currents
Placing a sheet of shiny foil behind radiators prevents heat radiation reaching the wall and conducting outside. Instead, it is reflected back into the room.