Interim Electrification of Heat research touts heat pump efficiency gains

New findings from the Electrification of Heat (EoH) Demonstration Project concludes that there is growing evidence that heat pumps are suitable for use in a wide number of UK homes.

Data from hundreds of homes has been collected from the ongoing EoH research. The project is funded by the government to study the practicalities of installing and using heat pumps in the UK.  The latest interim findings from the study noted that innovations in system design and the opportunities for using higher temperature heat pumps would ensure well designed installations can function effectively even in colder UK temperatures.

The Interim data, which has been published by the Energy Systems Catapult, was taken from the monitoring of 742 heat pumps between November 2020 and August 2022.

System efficiency

Among the main conclusions of the interim findings were that the median Seasonal Performance Factors (SPFs) recorded during this testing period was measured at 2.80 – a significant increase on previous measurements taken from separate heat pump trials conducted between 2011 and 2014.

The SPF is used to understand the in-situ efficiency of a heat pump system over the course of 12 months, researchers on the project stated.

A statement on the EoH interim findings said that innovations across the sector in the design of heat pump systems themselves was a likely contributor to improvements in the average SPFs rating over the last ten years.  Researchers added that there was room for further efficiency improvements to be made around the operation and design of heat pumps.

They said: “Whilst the average performance has improved, performance variation remains high. This suggests that progress is still required to improve the consistency of heat pump design and installation to support a large-scale rollout of heat pumps in existing homes and to deliver positive environmental and consumer outcomes.”

Another focus of the EoH study was looking at how heat pumps performed during colder days in the UK. This focus looked at occasions where average daily temperatures fell to around -6 deg C.

Researchers on the project said that there was only a marginal decline in system performance.  The median system efficiency was recorded at 2.44 on the coldest days during the research period.

Researchers stated: “This result indicates that heat pumps continue to operate with high efficiency – providing the requisite heat to homes – in a wide range of property types even in cold weather conditions.”

High temperature heat pumps

The research looked at the implications for using high temperature air source heat pumps. These technologies are described as being able to achieve flow temperatures similar to those of gas boilers, the EoH stated.

One potential benefit of these systems is a reduction in the need for a deeper retrofit of existing buildings to ensure effective heating, the findings said.

Energy Systems Catapult added that the interim data released from the EoH project found that the high temperature heat pumps used in the project performed at a similar efficiency to the low temperature systems used in the research.

The researchers stated: “Heat pumps are controlled to only demand higher temperatures when it’s colder outside. During the project, these weather compensation controls rarely demanded higher temperatures, allowing the units to maintain good heat pump efficiencies whilst keeping a wider variety of properties warm year-round.”

Further updates to the EoH analysis will be made after the completion of the project monitoring period in Autumn 2023.

Marc Brown, business leader of homes at Energy Systems Catapult, said the latest interim findings showed the improvements being made by manufacturers in the performance of heat pumps.

He said: “With the release of this data, we can finally put to bed the notion that heat pumps do not work in cold weather conditions and that they are inefficient to run. We’ve observed the exact opposite. They are three times more efficient than gas boilers and work in cold weather conditions. Innovation is changing the game in the heating sector.”

Mr Brown said that it was important for the industry to not become complacent about the need for further research and development in how low carbon heating systems are used in UK homes.

He added: “At the risk of sounding like a broken record, innovation and training are critical to the success of a mass rollout of heat pumps. We’ve done the hard work and demonstrated that heat pumps work – the UK is heat pump ready. Now we need to apply those learnings. The government and the industry should commit to investing in upskilling existing installers in low carbon heating solutions and doing more to attract new talent into the sector.”