Chapter 2

Question 1

Thermal conductivity

Answer 1

A measure of how quickly thermal energy is passed through a substance by conduction.

Question 2

Buildings and heat

Answer 2

Buildings can be designed to reduce heat loss to the surroundings.
E.g
Thicker walls and double glazing - lower conductivity.

Question 3

Heating in homes

Answer 3

In order to save money, people can change the materials used in housing.
Energy-saving solutions cost money to buy and install. The payback time of an energy-saving solution is a measure of how cost-effective it is.

Question 4

Equation to calculate payback time

Answer 4

Payback time (years) = cost of installation (£) ÷ savings per year in fuel costs (£)

Question 5

Results of payback time

Answer 5

If the payback time is too long, the energy-saving solution is not cost-effective

Question 6

Factors that affect the conductivity of the walls of a house

Answer 6

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.