Your Heat Pump questions answered

Elmhurst’s Existing Dwellings Support Team has noticed a shift in the number of queries relating to heating systems. Following the release of the government’s Heat and Buildings Strategy and the Boiler Upgrade Scheme, the focus is now on heat pumps.

Damien Roberts, Existing Dwellings Manager What is a heat pump and how do they work?

There are different types of heat pumps such as air to water, water to air, and ground to water. They all work similar in concept to a fridge; they take heat from a low temperature source (like the air) and transfer this heat energy through a compressor, which increases the pressure of the energy thus increasing the heat. The heat is then circulated around the home through a heat exchanger.

Heat pumps are very efficient, with a greater quantity of heat being delivered through the home compared to the electricity it uses to generate this heat. The fact that they are a low carbon heating system is why government and the energy assessment industry are pushing to raise awareness and implement measures to encourage people to install them.

How does a heat pump reflect on an EPC?

Although Energy Performance Certificates (EPCs) do report the carbon emissions, the headline rating is a cost-based metric.

works well at predicting the energy costs of a home fitted with a heat pump, compared with, say, a condensing boiler. Where an assessor selects the make and model of a heat pump from the PCDF, the assumed efficiency will be over 300%. Despite this impressive efficiency, under current fuel prices a shift to a heat pump is likely to cost slightly more and therefore the EPC score will get slightly worse.

The government has referenced this in the Heat and Buildings strategy, stating that once the current spike in gas prices subsides, the price difference between mains gas and electricity will be addressed by shifting levies from electricity. When the price of gas and electricity is rebalanced, that will be reflected in the SAP methodology and the EPC rating for a home with a heat pump will improve to demonstrate both the reduction in cost and carbon.

It has been rightly pointed out that the EPC does not recommend any type of heat pump to be installed as an improvement measure. This is because the methodology has not been kept up to date, and therefore the EPC is actually dissuading consumers away from the solution that government believes is the right one. The good news is that the assessment process is effective and well established, and that that the physics on which the methodology is based has proved the test of time. Government realises that some of the variables (such as carbon intensity), and the logic in how the recommendations are presented, are now out of date assumptions and that is why they are working on an update.

With the methodology likely to change in 2022 we are pushing for changes to the current list of improvement measures (Appendix T) that are applicable to recognise heat pumps. This would mean that a stakeholder looking at an EPC in in the future would see a heat pump as a recommendation. This leads on to what we are doing now to help our domestic energy assessors deliver valuable energy advice to their customers. We are working on new training material for heating systems that will focus heavily on heat pumps providing more technical details on how they work and the impact on the EPC, which we hope to release later this year. We are also redeveloping our ‘Energy Report’, which our members can use as a tool for providing advice which will show the three different metrics of cost, carbon and energy used. Whilst this is not a replacement for the EPC, it could be used in addition to it and can be shown to customers reflecting how efficient their home will be by installing a heat pump.

The government has referenced this in the Heat and Buildings strategy, stating that once the current spike in gas prices subsides, the price difference between mains gas and electricity will be addressed by shifting levies from electricity.