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By Graham Stringer MP - 17th November 2010
Graham Stringer MP examines the contribution of heat pumps to energy efficiency measures ahead of his Westminster Hall debate on the subject.
In the drive to reduce carbon dioxide and improve the environment it is tempting that anything badged as renewable gets public subsidy. The huge waste of public money and the industrialisation of the countryside with the investment in wind farms has shown that with this approach the cure can be worse than the illness.
In the adjournment debate on Wednesday on 'heat pumps' I want to explore whether the mistake with wind farms is about to be repeated with heat pumps.
Let me start by saying that I am impressed by the potential contribution that heat pumps could make to our future energy needs, but we must get complete assurance that the installed technology actually delivers what it says on the box. These pumps are a big investment for the householder and taxpayer and both deserve that reassurance.
Heat pumps extract heat from the ground or air and redirect the heat for space heating and hot water. The efficiency of heat pumps is measured by their co-efficient of performance (CoP) - the ratio of heat produced per unit of electricity consumed in generating that heat. A CoP of 3 means that 3 kWh of heat are output for 1kWh of electricity used to run the pump. Higher CoP values represent relatively more efficient heat delivery.
However, CoP values vary by season: the colder the ground or air, the more work the pump has to do to raise the temperature to acceptable levels for domestic heating and the more energy is consumed. Poor design and installation can also affect CoP. In well insulated buildings with low temperature under floor heating (40 degrees centigrade), ground source heat pumps can be beneficial. Conversely, poorly insulated buildings where the pump is required to heat high temperature radiators (60 degrees centigrade) and hot water, their performance is less impressive.
The 2009 European Directive on Renewable Energy excludes low performing heat pumps from contributing to the renewable energy targets, where it states that 'Only heat pumps with an output that significantly exceeds the primary energy needed to drive it should be taken into account'. From other data we can deduce that that the EU implicitly requires that heat pumps achieve a CoP of 2.875 before their energy can contribute to the renewable energy target.
Shockingly the most recent study of currently installed heat performance showed only 9 out of 47 sites with air source heat pumps achieved the EU standard.
Worse than this, a study undertaken by Atlantic Consulting – "Fluorocarbons' Contribution to Air-Source Heat-Pump Carbon Footprints" - showed that the contribution of fluorocarbons to the carbon footprint of a heat pump was considerable.
Ministers have claimed to me in written parliamentary answers that these rates are negligible. They are not. In power generation fluorocarbons added 20 per cent to the carbon footprint of a heat pump.
Currently the government is considering, in detail how the renewable heat incentive (RHI) will work.
Heat pumps are definitely sustainable heating systems as they extract heat from renewable sources. But before they are invested in, someway has to be found of assessing and certifying each installation so that it makes a positive rather than a negative contribution.
Article Comments
There is a big regulatory problem in terms of making sure that heat pumps are properly specified and installed and only then in a well insulated house. However there is an operational problem as well, if the householder leaves the window open, heat is lost and the radiator temperatures rise as a result, the efficiency of the heatings system falls (as it says above). Of course that applies to a gas centrally heated house, it is just that the problem is compounded if are using a heat pump.
I would argue that, yes, heat pumps don't always work efficiently. But the much bigger problem is getting householders to manage their heating systems properly. There is a very big group of householders that have reasonable incomes that don't give much thought to their heating systems or heat loss or the control systems. A lot of householders don't understand why they should use room thermostats and how to make best use of thermostatic radiator valves (TRVs) or even why you should shut your curtains at night and they aren't really inclined to find out.
John Ackers
19th Nov 2010 at 11:12 am
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