1. Describe how heat is transferred by conduction and convection.
3. How does this stop heat loss by convection?
2. This is cavity wall insulation. It contains a foam
which traps air. How does this stop heat loss by
conduction?
4. Cavity wall insulation costs £3250 to install.
It saves the family £250 per year.
Calculate its payback time.

2. Describe how heat is transferred by conduction and convection.
3. How does this stop heat loss by convection?
2. This is a section through a double glazing unit.
How does this stop heat loss by conduction?
4. Double glazing costs £4600 to install.
It saves the family £200 per year.
Calculate its payback time.

3. Describe how heat is transferred by conduction and convection.
3. How does this stop heat loss by convection?
2. This is Draught excluder.
How does this stop heat loss by conduction?
4. Draught excluders costs £16 to install.
It saves the family £10 per year.
Calculate its payback time.

4. Describe how heat is transferred by conduction and convection.
3. How does this stop heat loss by convection?
2. This is Hot water boiler jacket.
How does this stop heat loss by conduction?
4. Hot water boiler jacket costs £80 to install.
It saves the family £30 per year.
Calculate its payback time.