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Upcoming Changes to Part L - Heat Pumps

Closing the heat pump loophole

If you’ve ever dabbled with the use of a heat pump heating system in a new house, you’ll have discovered that this is a good way of showing compliance with the SAP calculation without having to worry about spending extra on insulation details... sometimes passing the SAP by 15 or even 25 percent.

This happens because of the way homes which have electric heating are treated in the Target Emission Rate assessment...

Using Electric Heat Pumps..

If a house uses an electric heat pump, panel heaters or storage heaters for main heating, the target in the SAP is the same which, considering a heat pump is three to four times more efficient than a panel heater, is seen by many to give heat pumps an unfair advantage in the assessment.

Draft documents are now available online which give us an indication into how Part L / Section 6 may be changed as part of the next update, which could go live later this year.

According to the Welsh Assembly consultation papers, a new ‘Elemental Recipe’ equation is going to be used to work out Target Emission Rates in the future, which will be based on one of five heating types.

As this document stands, any dwelling which has electric heating will be measured against a target which is based on a heat pump with a CoP efficiency of 3.2 (otherwise written as 320%) providing 90% of the heating, and the rest from panel heaters.

So this means newly built houses with heat pumps will be assessed based on a similar heating type, so this will remove the current anomaly in SAP which means heat pumps fly through the assessment.

More difficult to show compliance

On the flipside, the use of panel or storage heaters will prove incredibly difficult to show full compliance, even with the inclusion of large PV arrays.

This is because a panel heater (which is 100% efficient) is being compared to a heat pump (which can reach figures of 300-400%), so you will need to compensate for this much lower efficiency by spending extra time, money and effort on improving all other elements of the building.

The other ‘Elemental Recipes’ are based on gas, LPG, oil and biomass boilers providing 100% of the dwellings heating demand. So far there has been no talk of using this approach for SAPs in England or Scotland, but alternative mathematical ideas are being considered.

Jon Ponting

Author: Jon Ponting

This article was published by Jon Ponting on 18.01.2013.