Heat Pumps, Ground Source, Geothermal, John Cantor, Wales, UK  
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Carbon Dioxide Pollution figures for various fuels (updated 2010)

(SAP 2009 version 9.90)
See assumptions below.

Running cost for various heating methods

Updated June 2008.

Notes and assumptions.

It is now quite difficult to compare fuel prices due to 2-tier pricing. Furthermore, prices are presently changing. Please check your local supplier.
Oil cost 55p/ litre.( 2008), LPG, 39p/ lit. Electricity 12.5p/unit
Gas condensing boiler efficiency 90%
Oil boiler efficiency 85%
LPG condensing boiler efficiency 88%
Electricity 100% efficient at point of use. Off-peak storage heaters often 85%, but electricity pollution figures are often better at night, so these two factors tend to cancel each other out.

The COP (coefficient of performance) of a heat pump is the ratio of input to output.

Variation in efficiency with heated water temperature.

You MUST understand this graph, please have a good look.

The above graph shows how important it is to keep the heated water temperature as low as possible. To attain a COP of 4, it is necessary to keep the heated water down to 35°C. This is only possible with a good underfloor heating system. If radiators are used, then they must be oversized to keep the temperature down as far as possible.
The red line shows how much the efficiency improves if spring water is used. Unfortunately, this is not commonly available.
The difference between the two lines demonstrated how important it is to have a large ground collector area that will keep the source water as warm as possible.

The Graph below might be useful when assessing the benefit of running a heat pump.

The vertical scale on the left shows CO2 pollution per kWh of heat delivered. The two horizontal lines show figures for mains gas and oil heating. The curves are for heat pumps with COP's up to 5. Direct electric heating has a COP of 1, and this is shown on the left.
The UK government figure for CO2 pollution caused by electricity generation has been 0.422 (kg co2/kWh). However the SAP 2009 version 9.90 figure is 0.591 (kg co2/kWh). The actial present figure is around 0.5, and will tend to be high in mid winter when coal power station are brought on-line to meet increased electricity demand.


The graph below gives an indication of the possible harm caused by a refrigerant leak compared to the saving of CO2 released during a 10 year period of a heating system. Like the domestic fridge, refrigerant leaks are very rare.

Graph taken from expected consumption for a year 2002 regs. house.
10,500kWh space heating, 3,600kWh. hot water.
See ECOLOGY page for more details



John Cantor Heat Pumps © 2007