Thursday, April 11, 2024

Heat pumps: Up to three quarters of homes in study ‘fitted with wrong size’

Around 70% of homes with heat pumps tested in a study were found to have had the wrong size installed, new research suggests.

It means that the householders faced higher energy costs – or a colder home – as a result.

The findings from the joint study by three energy monitoring experts – Build Test Solutions, Veritherm and Elmhurst Energy – will fuel the argument of those who point to the success that other European nations have had with heat pump installation.

“The UK Government has set a target of 600,000 heat pumps installed by 2028 but without a more accurate approach to measurement, people will never trust the new green technology and that figure won’t be achieved,” says Richard Jack, technical director at Build Test Solutions.

“Heat pumps are really important for decarbonising heat and achieving net zero but it is crucial that we maximise efficiencies. Before any heat pump is installed, specific heat loss measurement is needed to ensure the correct size for the property’s requirements.

“The performance gap between the assumed and actual heat loss calculations will have significant implications for residents if we don’t make changes – with the risk of higher costs and colder homes.”

The study of 56 homes (measuring heat loss through BTS’s SmartHTC system or a Veritherm overnight test) included several types of dwelling, weighted towards detached and more recently built homes.

Oversized heat pumps cost more to run

The research found that the difference in heat loss between that calculated and the measured heat loss was a substantial 35 per cent. There was a significant bias towards overestimating the heat loss; 59 per cent of houses.

An oversized heat pump incurs higher capital costs, of around 10 per cent on average, alongside higher maintenance costs and lower running efficiency.

With an undersized heat pump, the risk is that the home will not be warm enough during the coldest periods, driving the occupant to turn to more expensive heating methods, such as a fan or oil heater.

Making measurement mainstream

“Measuring the thermal performance of a home should be the first step in any consumer heat pump journey,” said Mr Jack. “Measurement helps engage residents, leading to higher heat pump uptake and trust, and reduces risk when making this investment.”  

Build Test Solutions, Veritherm and Elmhurst Energy suggest that both industry standards and software tools should be updated to recognise the role of measured heat loss as part of the heat pump design process, sizing and specifying.

Chris Ricketts, head of consultancy at Elmhurst Energy adds: “Heat loss measurements provide a more accurate method to determine the overall heat demand of a building, which can feed down to the design process and improve efficiencies.

“It is a service that installers can integrate within their offering, using software tools to capture and present the data. Residents see value in this information, and the savings that can be achieved through doing this accurately more than covers the costs.”

Tom Fenton, CEO at Veritherm said: “If the industry does not work together, residents will be forced to pay unnecessary costs, and we’ll never make heat pumps a trusted low carbon heating alternative for our homes.”

Read the full report and find further resources from Build Test Solutions, Veritherm and Elmhurst Energy at

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