The suitability of clean heating options for challenging dwelling types

Only around 11% of occupied homes in Scotland have renewable or low-emission heating systems, with the majority still relying on high-emission sources like gas and oil. To meet Scotland’s net zero greenhouse gas emissions target by 2045, over 2 million homes will need to transition to clean heating systems.

Heat pumps and electric resistive heating are the main clean heating options available today and they are likely to work well in most homes. This project investigates the feasibility of clean heating, especially heat pumps, in challenging home types in Scotland, in terms of practicality and cost effectiveness.

We reviewed academic research, industry literature and case studies, and conducted a combination of surveys and semi-structured interviews with industry experts. We identified the advantages, disadvantages, contradictory evidence and research gaps surrounding the application of clean heating technology in Scotland.

We reviewed studies and identified the following challenging dwelling types:

• Older properties from before 1919
• Rural properties
• Small properties
• Flats and tenements.

Findings

Overall, while there are challenges to implementing heat pumps across different property types, innovative solutions and careful planning can facilitate their adoption and contribute to decarbonising heating systems in Scotland. We found:

• Older properties: Buildings from before 1919, often with solid walls and potentially holding protected status, may pose challenges for both insulation upgrades and heat pump installations due to planning constraints and preservation concerns. Whilst it is common to prioritise improving energy efficiency prior to the installation of heat pumps, recent studies have concluded that heat pumps can operate effectively when installed into homes that have not undergone energy efficiency upgrades. It is also important to note that while increasing energy efficiency stands as a crucial objective, the structural integrity and overall condition of the building need consideration. It is important to ensure a building is in good condition before installing new heating systems, in particular, repairing structural issues, water ingress and damage. Consequently, any new heating technologies will be more effective and contribute to the building’s overall energy performance.
• Rural properties: Rural areas can present unique challenges due to grid capacity limitations and vulnerability to power cuts. However, heat pump adoption rates are already highest in off-grid regions due to cost savings compared to existing off gas network fuel sources. Evidence shows that heat pumps can operate well in cold climates, with studies evidencing effective performance compared to gas boilers, even at extremely low temperatures. No significant barriers to heat pump adoption have been identified. Heat pumps with additional corrosion protection are available for coastal areas. However, a lack of local contractors, increased servicing costs and higher costs for energy efficiency improvements pose challenges in remote areas, particularly the Scottish islands.
• Small properties: Space constraints, such as limited room for hot water storage and radiator upgrades, present challenges for heat pump installations. No evidence of a quantitative threshold to define ‘small’ was identified. Innovative solutions like compact heat batteries or external hot water storage may offer alternatives.
• Flats and tenements: In addition to the challenges presented above, flats and tenements face difficulties due to constraints on external locations for air source fans, as well as coordinating changes with neighbours and building owners, due to differing tenancy arrangements. Case studies highlight the importance of careful planning and resident input in determining suitable locations. These are similar to the challenges to basic repairs and maintenance of blocks of flats and tenements and to fabric improvements, such as insulation. Fifth generation heat networks, with individual indoor heat pumps supplied by communal ground sources may provide a potential solution.

If you require the report in an alternative format, such as a Word document, please contact info@climatexchange.org.uk or 0131 651 4783.