1. P1.1.4 Heating and
insulating buildings
evaluate the effectiveness of different
types of material used for insulation,
including U-values and economic factors
including payback time

2. KEY WORDS
Energy
Work
Transfer
U-values
Payback time
Specific heat capacity

3. One way to reduce the amount of heat that escapes from
a house is to insulate it so that the heat energy escaping
is reduced
Where is the most heat lost?
What can be done to reduce the heat loss?

4. Important ways of reducing heat loss in a home are:
• Loft insulation – this is a thick layer of fibre glass laid
across the loft space. It reduces conduction and
convection.

5. Important ways of reducing heat loss in a home are:
Cavity wall insulation – this is foam squirted between
the gaps between bricks. It reduces conduction and
convection.

6. Important ways of reducing heat loss in a home are:
A jacket for the hot water tank this reduces conduction and
radiation.

7. Air is an insulator/ poor conductor
Convection stopped foam is an insulator/ poor
conductor

8. Heat is conducted through the
glass
Heat passes through the glass and
air by radiation
Heat crosses the gap by
convection
Light
X-rays
Sound
Radio

9. Cuts down convection currents
Air pockets trap air (from moving)
Foam is a poor conductor/ good
insulator
Evaporation of water
takes energy from the house

10. convection
conduction

11. 100 – (15+15+10+25) = 35%
Cavity wall insulation and roof
insulation

12. Payback time – the time taken to recoup the
initial payment - for these is calculated by:
Initial cost ÷ annual saving
Example
It costs £250 to install and fit loft insulation in a
house. It saves £50 a year.
How long is the payback time?
Solution
Using: Payback time = Initial cost ÷ annual saving
Then £250 ÷ £50 = 5 years.

13. U-values
a) U-values measure how effective a material is as an insulator.
The U-value shows how fast heat can transfer through a material.
The higher the U-value the faster the heat transfer.
b) The lower the U-value, the better the material is as an insulator.
Good insulators have a low U-value.

14. 1 – it has the highest U-value

15. 3 and 4 OR 1 and 2
U-values for the 20 mm windows are the same or
higher than those for the 16 mm windows
therefore the 20 mm windows are no more energy
efficient than 16 mm windows

16. c) Solar panels may contain water that is heated by radiation from
the Sun. This water may then be used to heat buildings or provide
domestic hot water.

17. The specific heat capacity of a substance is the amount of energy
required to change the temperature of one kilogram of the substance by
one degree Celsius.
E is energy transferred in joules, J
m is mass in kilograms, kg
is temperature change in degrees Celsius, °C
c is specific heat capacity in J / kg °C
It indicates how much energy a substance can store.
E = m x c x

18. Example
How much energy is required to heat 3 kg of water from
20 °C to 100 °C. The specific heat capacity
of water is 4200 J/ kg°C.
Solution
Using E = m x c x
Substituting
m = 3 kg
c = 4200 J/ kg°C
T = 100-20 = 80 °C
Gives E = 3 x 4200 x 80
= 1008000 J

19. Example
How much energy is required to heat 2 kg of water from
10 °C to 110 °C. The specific heat capacity
of water is 4200 J/ kg°C.
Solution
Using E = m x c x
Substituting
m = 2 kg
c = 4200 J/ kg°C
T = 110-10 = 100 °C
Gives E = 2 x 4200 x 100
= 840000 J

20. Other ways of reducing energy loss include
replacing filament bulbs with low energy light bulbs
and LED lighting

22. Replacing old appliances with
energy efficient ones
Newer appliances have an
energy label. More efficient
appliances are rated A.
Other ways of reducing energy loss include

23. An advertisement in a shop claims that:
‘Replacing an old freezer with a new ‘A’ rated freezer will benefit the
environment.’
Do you agree that replacing the freezer will benefit the environment?
YES
Less electricity used /
energy needed
Less fossil fuels burned
Less polluting gases
emitted
NO
Old freezer must be
disposed of
Hazardous chemicals inside
freezer eg CFCs
Lot of Energy used in
producing new freezer