10 March 2025
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One of the most common misconceptions about heat pumps is that they are not suitable for older properties. To separate fact from fiction, Olivia Downing, Head of Marketing at NIBE UK, explores the latest research and shares two case studies which demonstrate the effectiveness of heat pumps in historic listed buildings.
Heat pumps have been proven to work well in all properties, regardless of type or age. However, many homeowners – and some installers – still have unanswered questions about their effectiveness in older properties. The common misconception that heat pumps are only suitable for new build homes could cause a significant barrier to adoption in the UK, which has the highest proportion of older housing stock in Europe. When designed and installed correctly by a trained and qualified engineer, heat pumps are a highly efficient, low carbon heating solution for both new build and older properties, in most instances costing less than a gas boiler to run, even with the UK’s wide spark gap between electricity and gas. Our heat pumps have been successfully used in a wide variety of existing buildings, from 1950’s family homes to Listed buildings built more than 600 years ago.
What does the research say?
Critics claim that heat pumps cannot work in older homes, those built with solid brick or stone walls or where insulation is lacking, however, large-scale feasibility trials and field studies counter this claim. The Electrification of Heat (EoH) demonstration project1, which installed 742 heat pumps systems and monitored their performance between October 2020 and September 2023, at an average of 2-minute time intervals. The heat pumps were installed in a wide variety of UK homes, including 58 properties built before 1919 and 105 properties built between 1919 and 1945. Analysis revealed no statistically significant variations in Seasonal Performance Factor (SPF) based on house type or age. Heat pumps in older properties performed consistently well, maintaining an average SPF of above 2.7 in real-world conditions.
Data from the Fraunhofer Society2, a leading applied research organisation based in Germany, further supports the effectiveness of heat pumps in older homes. Monitoring the performance of 300 heat pumps over 20 years, heat pumps were found to outperform gas boilers even in buildings over a century old. Heat pump users, including those in older homes, report high satisfaction with their heating systems, according to a survey by Nesta. The survey compared heat pump users to gas boiler users and found similar satisfaction levels. Overall, 81% of heat pump users, and 83% of those living in Victorian or older properties, were satisfied or very satisfied with their heat pumps compared to their previous heating systems.
From historic elegance to sustainable excellence
Lea Hall, a Grade II* listed property in Essex, illustrates the potential of upgrading older properties with heat pumps. Built in the 1400s and set within 49 acres of meadows, woodlands, and watercourses, Lea Hall is a double-moated country home steeped in history. When developer AJ Wadhams purchased the property in 2017, the goal was to create a futureproof, sustainable living space while respecting its heritage features. Together with energy efficiency upgrades, that included thermal lime render, sheep’s wool wall insulation and underfloor heating, the system was given a low carbon upgrade by Delta Mechanical UK Ltd, combining NIBE’s Ground Source Heat Pump (GSHP) with seven NIBE Air Source Heat Pumps (ASHPs) and monitored by myUplink, which helps residents to take complete control over the heat pump system while further improving energy efficiency. The system is now providing efficient low-carbon heating across the property, including all seven bedrooms. Will Blair from Delta Mechanical said, “Lea Hall presented a great opportunity to showcase how heat pumps are suitable for both new and existing properties, regardless of their age or energy efficiency rating.”
Breaking down barriers in older homes
While heat pumps form the core of domestic decarbonisation strategy, there is no single technology with the capability to do it all. By combining the latest developments in renewable technology, we can remove some of the common barriers to installation and drive energy efficiency to the maximum. This approach was adopted by Holt Plumbing & Heating, when they were contracted to upgrade the heating system at Lackington Mill, an 18th century former water powered corn mill on the River Piddle in Dorset. A NIBE GSHP was specified for its power, high seasonal performance factor (SPF) and dual compressors, which make it ideal for properties with large heating requirements. However, the property featured several ornamental trees with deep root systems that made digging boreholes or even installing a horizontal ground loop very difficult. The owner was keen to preserve the trees, so Holt suggested the addition of NIBE PhotoVoltaic Thermal units (PV-T), an innovative heat source for NIBE GSHPs which removes the need for extensive groundworks or boreholes. In combination with a GSHP, underfloor heating and four Mechanical Ventilation and Heat Recovery (MVHR) units, this system reduces energy demand and optimises comfort, transforming a character property steeped in history into a luxury sustainable home fit for the future.
Solutions for all homes
The misconception that heat pumps are unsuitable for older properties has been thoroughly debunked through research and real-world case studies. Projects like Lea Hall and Lackington Mill demonstrate how heat pumps, combined with thoughtful upgrades and modern technologies, can deliver low-carbon, highly efficient heating in properties of any age.
For installers, the key to success lies in understanding the unique challenges of older properties and tailoring solutions accordingly Detailed property assessments should be conducted to address factors such as insulation, heat loss and the feasibility of groundworks. Innovative technologies, such as PV-T, can be utilised to overcome site-specific challenges, such as preserving heritage features or navigating restricted outdoor spaces. Proper training and certification are also critical, including manufacturer training on specific products and technologies. Additionally, clear communication with homeowners about expected costs, benefits, the best way to run their system – heat pumps are not the same as gas boilers so end users must be educated on their efficient operation - and potential energy savings, can help set realistic expectations and build trust. Retrofitting existing homes is a significant part of the decarbonisation challenge and represents a substantial opportunity for installers. By adopting advanced solutions and applying professional expertise, installers can confidently expand their scope to include older properties, contributing to the UK’s shift toward sustainable, low-carbon heating systems.
Source
1. https://es.catapult.org.uk/report/electrification-of-heat-home-surveys-and-install-report/
2. https://www.ise.fraunhofer.de/en/research-projects/wp-effizienz.html
