When our homes are warm we feel
comfortable and we can relax.
If the inside is warmer than the
outside, then energy will be lost.
Once we have heated the house we must keep replacing the heat otherwise it will
cool down.
1. List the things that might effect how much you would have to pay to keep a
house comfortably warm.
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2. What things could you do to reduce the cost of heating a house?
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3. Why do you think it is important to reduce the amount of energy used to heat a
house?
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One of the most important factors that influence the cost of heating is our choice of
energy source or fuel.
1. Some energy sources cost a lot more than others. Below is a table of typical
fuel costs for two consecutive years 2004 and 2005.
Energy
Source/Fuel
2004
2005
pence/kWh pence/kWh
Oil
3.20
3.74
Coal
4.10
4.32
Natural Gas
4.38
3.77
Stored Gas (L.P.G.)
5.15
5.10
Electricity Ordinary Rate
9.69
10.47
Electricity Economy 7
Rate *
3.44
4.17
% Rise in
cost from
2004 prices
*Special meters are installed for Economy 7, which only measures the amount of electricity used at
night. Ordinary rate is used during the day.
a. Which is the most expensive energy source for both years? _______________
b. Calculate the % rise in price for each energy source compared to 2004 prices.
c. Which energy source/s increased in price?
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d. Which energy source increased in price the most?
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e. Which energy source/s decreased in price?
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f. Which energy source decreased in price the most?
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g. If you had to make a judgement about reducing your fuel bills which energy
source might you decide to opt for? Explain.
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2. Two very similar houses heat their homes in different ways.
(a) Complete both the Gas and Electricity bills if the price of each energy unit is:
1 unit of Gas is 1.92 pence and 1 unit of Electricity is 9.45 pence.
(b) Which bill is the most expensive? ___________________________________
(c) What could you do to reduce the cost of heating your house?
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Generating some of our own energy might be a way forward to reducing energy
bills. There are various ways in which we could do this:
The kinetic energy in the wind is converted into electricity.
Domestic wind turbines could be used to generate small amounts of
electricity. Installation of a reasonably sized wind turbine will cost £2,500 to
£5,000. In a good location (with an average wind speed of 5 metres per
second), you should get between 1,500 and 2,000 kWh per year. This would
offset £150 to £200 of grid electricity, so the payback time is still fairly long.
Solar panels use the heat energy from the sun to heat
water, which can be stored in a hot water tank for
future use. The cost of a commercial flat plate system,
including installation, for an 'average' house ranges from about
£2,000 to £5,000. For a family of four, a well designed Active
Solar Heating system should contribute between 1,500kWh
and 2,000kWh, which will be equivalent to 40 to 50% of the
household's water heating energy needs. The value of this
saving will depend on the type of energy displaced.
Again the payback time will be fairly long.
Solar Panels
Solar cells convert sunlight directly into electricity. A
Photovoltaic roof will cost between £6,000 and £7,000. A
1 kilowatt (1kW) system will cover about 10 square
metres, and produce about 750kWh (units of electricity)
over a year - mostly in the summer. As 1kWh of gird
electricity costs about 10p, this annual output would offset
about £75 - so you can see that the payback time is
currently quite long.
Summary
On a windy site, a wind system may be a better financial option than solar PV or solar
heating, but bear in mind that good wind sites are more rare than good solar sites, and a
turbine will need more ongoing maintenance than a solar roof. However, each method of
generating energy would save you money on you energy bills but you would take a long
time to cover the initial installation costs.
Extension work
You are a global citizen who is concerned about reducing your fuel
bills but you are also concerned about the environment.
Discuss what factors might influence your decision about the type of
energy source you would use to heat your home.
Write a report using the following frame.
Describe the factors that you have considered.