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New Study Shows that Heat Pumps Work Well in Cold Weather Conditions.

Authored by Marco on March 27, 2023

Heat Pump GTEC

Interim performance results from the Electrification of Heat Demonstration Project (EoH) are in – and its good news all round for heat pumps.


The report, written by Energy Systems Catapult and published by the Department of Energy Security and Net Zero (DESNZ), analyses monitoring data recorded between November 2020 and August 2022 from more than 350 homes, crossing a broad spectrum of housing types and ages, with a variety of heat pumps in situ.


Key findings include:

  • Heat pumps are over three-times more efficient than top spec gas boilers
  • Average seasonal performance factor (SPF) of air source heat pumps (ASHPs) was 2.8, which equates to 280% efficiency
  • During cold weather, ASHP efficiency dropped only slightly to 244% on average.

How efficient are air source heat pumps?

ASHPs in the trial achieved an average Seasonal Performance Factor (SPF) of 2.8 or 280% efficiency. This is a significant improvement compared to previous field trials, namely the Renewable Heat Payment Premium, which collected data between 2011 and 2014.

The efficiency of high temperature ASHPs was similar to that of low temperature ASHPs. High temperature ASHPs use weather compensation controls to automatically request high temperatures when the temperature drops very low. The rest of the time, they operate at low temperatures which explains the similarity in efficiency.

Hybrid heat pumps did not perform as well as standalone ASHPs. Estimated overall efficiency from hybrid heat pumps commissioned to run automatically prioritising optimum cost was between 126% and 142% and they met between 32% and 50% of space heating demand.


What is Seasonal Performance Factor of heat pumps?

SPFs indicate the in-situ efficiency of a heat pump system over the course of 12 months, including all four seasons. To achieve a suitable level of accuracy for the trial, heat pumps that did not have 12 months of continuous monitoring were left out of the interim figures.


Do heat pumps work in cold winters?

Yes! This study has provided evidence that even when the temperature drops to below 0 oC, ASHPs can extract enough heat from the air at a decent efficiency to ensure homes remain warm and energy costs do not skyrocket.

During the coldest days of the study, average temperatures fell to -6oC. Heat pumps continued to operate at high efficiencies, dropping only marginally to 244% (median).

While the efficiencies identified in the report are good, we know we can do better with high quality training and the right software.


Are heat pumps cheaper to run than gas boilers?

Despite being around three-times more efficient than gas boilers, heat pumps are not necessarily cheaper to run – yet!

From October 2022 to March 2023, the average cost for 1 kWh of gas was around 10p, whereas electricity is more than three times higher at around 34p/kWh, which should roughly balance out the cost taking efficiency into account, although standing charges for electricity are also much higher than gas.

However, as we shift towards the electrification of the heating sector, things are changing. There is talk of shifting environmental taxes from electricity to gas, which could take around £600 per year off the cost of running a heat pump in a large home.

Additionally, we should start to see more energy suppliers offering discounted heat pump tariffs, such as Octopus Energy’s Cosy tariff, that offers variable off-peak rates and decreases costs overall.

Monitoring under the EoH will continue until September 2023, following which final results will be published, including data from ground source heat pumps.

View our training courses to find out more about becoming a heat pump installer.


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