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Heat Questions - GCSE Level

Q14. A householder wants to reduce her energy bills.

She collected information about a number of ways of reducing energy used.

The information is shown in in the table below:

Ways of reducing energy used
Cost to buy and install in £
Money saved per year in £
Install an energy-efficient boiler
2,000
320
Insulate the loft
400
200
Install double-glazed windows
12,000
120
Install cavity wall insulation
415
145

 

(a) Use the information in the table to compare the different ways of reducing the energy used.

Your answer should include some calculations.

This type of question is marked in two ways:

- the examiner looks for relevant points

- but also for a logical sequence...

It is not just a 'tick fest' - but a marker does look to see how many relevant points you have made, then considers how you have strung them together to put your answer into a 'level'

Level 3:

There is a comparison of energy saving methods and their cost effectiveness with appropriate calculations. Comparison to include further detail.
5 - 6 marks
Level 2:

There is at least one clear comparison of energy saving methods and their cost effectiveness with an appropriate calculation
3 - 4 marks
Level 1:

There is a relevant statement about an energy saving method

1 - 2 marks
Level 0:

No relevant information
0 marks

 

Examples of physics points that should be made in the response:

Examples of relevant statements:

energy efficient boiler saves the most (energy / money) per year

loft insulation costs the least to install

double-glazing costs the most to install

Examples of statements that include cost effectiveness:

loft insulation is the most cost effective in the long term

double-glazing is the least cost effective

loft insulation has the shortest payback time

double-glazing has the longest payback time

payback time calculated for any method

Examples of further detail:

for cost effectiveness install in the following order: loft, cavity wall, boiler, double-glazing

for reducing energy use install in the following order: boiler, loft, cavity wall, double glazing

don't install double-glazing for insulation purposes

double-glazing won't pay for itself in your lifetime

justified choice of best / worst method

Extra information - payback time calculations:

energy efficient boiler: time to recoup the outlay = 6.25 years

loft insulation: time to recoup the outlay = 2 years

double glazing: time to recoup the outlay = 100 years

cavity wall insulation: time to recoup the outlay = 2.86 years

[6 marks]

(b) Increasing the amount of insulation in a house affects the total U-value of the house.

(i) What is meant by the term 'U-value'?

A U-value gives information on how effective a material is as an insulator. The lower the U-value the better the insulator and the lower the rate of energy transfer through it.

[1 mark]

(ii) How is the U-value affected by increasing the amount of insulation?

It decreases.

[1 mark]

(8 marks total)