Heat Pumps in Historic Buildings

[edit] Air Source Heat Pump Case Studies – Large Buildings Published 13 January 2026 Download Air Source Heat Pump Case Studies – Large Buildings (PDF, 2.56 MB)

Electrifying heat is key to reducing reliance on fossil fuels for historic buildings. No technology is better placed to electrify heat for space heating than heat pumps. The technology is mature, and if the entire heating system is well-designed, it will deliver comparable running costs to a natural gas system. Air source heat pump (ASHP) technology can be installed quickly and has lower capital costs than other heat pump technologies. This makes air source a key technology in the decarbonisation of space heating.

This report is a continuation of the previous study ‘HEAG0316: Heat Pumps in Historic Buildings, Air Source Heat Pump Case Studies – Small-scale Buildings’, and focuses on five large historic buildings across four sites. In 2022, we commissioned environmental building services engineers, Max Fordham LLP, to review the performance of ASHPs in larger historic buildings. The research aligns directly with Historic England’s objectives for climate change and sustainability.

The four site visits took place between November 2022 and February 2023. The engineers from Max Fordham LLP carried out visual inspections of the ASHP installations and associated heating systems. They also interviewed building users to gauge their opinions on running costs, thermal comfort, noise, cold air plumes, and visual appearance. The engineers took as many quantitative measurements as possible, but time constraints and minimising the intrusiveness of site visits meant that most of the findings were qualitative.

The key findings were:

• ASHPs work well in historic buildings and are a readily available means of decarbonising heating systems.
• Issues with the heating system’s performance were usually caused by the design of the heating distribution or delivery, rather than by the ASHPs themselves. For example, convectively heating draughty areas with a high air change rate can be problematic, regardless of whether the heat source is a boiler or a heat pump.
• The visual and noise impacts of the ASHP units were not an issue for any of the users, as was the case in the previous ASHP study.
• Carbon dioxide refrigerant systems present unique opportunities for reusing existing pipework, reducing embodied carbon emissions, and reducing unintended emissions caused by refrigerant leaks.
• Building users need to have a good understanding of how to use system controls to maximise the efficacy of the system.

Contents

• Introduction
• Method
• Key observations and findings
• Case Studies
• Conclusions
• Acknowledgements
• Additional Information

Series: Guidance Publication Status: Completed Pages: 64 Product Code: HEAG326

Accessibility: If you require an alternative, accessible version of this document (for instance in audio, Braille or large print) please contact [mailto:customers@HistoricEngland.org.uk customers@HistoricEngland.org.uk]

This article appears on the Historic England website as "Heat Pumps in Historic Buildings" dated January 2026.

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