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Energy costs are at the forefront of everyone’s minds and using a heat pump can help reduce your heating bills, as up to 75% of the energy used can be provided from the ground. How much the heating bills will be and how much CO2 will be produced is very difficult to gauge unless a full SAP report is carried out on the individual property. This is simply because there are too many variables involved, for example the level of insulation, the ambient temperature, whether hot water is being produced, electrical tariffs, etc.
As a guide the current energy costs (Dec 07) are as follows:-
Gas 2.55p/kWh
LPG 5p/kWh
Electricity 9.3p/kWh
Oil 3.7p/kWh
Using a house with a space heating load of 15,500 kWh the annual costs of heating this property would be:-
| Fuel |
Annual cost (based on figures above) |
| Gas |
£395 |
| LPG |
£775.00 |
| Direct Electricity |
£1,441 |
| Heating Oil |
£573 |
If a heat pump is used in conjunction with underfloor and good insulation (with a COP of 4) then the cost of the electricity used for space heating would be approximately £360 per year. This cost could be further decreased if off-peak tariffs are used to run the heat pump.
If the heat pump was connected to radiators (COP of 3) then the cost of electricity used for space heating would increase to £480 and off-peak tariffs cannot be used. Payback periods would increase and the running costs will be higher than using a modern day gas condensing boiler.
(Figures quoted are illustrative only)
Carbon Emissions
From a green perspective, a ground source heat pump has one of the lowest CO2 emission rates per kWh of energy produced.
The following table is produced by the DTI in conjunction with BRE and gives CO2 emissions per kWh for different fuels.
| Fuel |
Kg CO2/kWh |
| Electricity |
0.43 |
| Natural Gas |
0.19 |
| Coal |
0.3 |
| Oil |
0.25 |
| LPG |
0.21 |
Although a Ground Source Heat pump uses electricity (which has the largest emission rate) as it can operate with a COP of 4, i.e. for every one kW of electrical energy used it produces 4 kW of thermal heat, the actual CO2 emission rate for providing heat to a building is 0.11kg CO2/kWh.
This shows a CO2 reduction of 43% over gas and 57% over oil. Using a green tariff would lower the actual CO2 emissions even further.
By selecting a Ground Source Heat Pump to provide a building’s heating requirement the Carbon emissions of the building is reduced and hence the building is more likely to pass building regulations.
For examples on how changing fuel sources, increasing insulation or adding solar panels to buildings, can alter a building’s carbon emissions, we suggest you visit www.playtheregs.com. The site is a simple on-line SAP assessment program written by the National Home Energy Rating (NHER) scheme and gives an indication on how changing a building’s characteristics can alter its SAP rating and carbon emissions.
Click here for details of off-peak tariffs.
Click here for a factsheet on ground source heat pumps, Building Regulations and Carbon Emissions.
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