The Electrification of Heat (EoH) demonstration project is funded by the Department for Business, Energy and Industrial Strategy  (BEIS) and seeks to better understand the feasibility of a large-scale rollout of heat pumps across the UK.

EoH aims to demonstrate that heat pumps can be installed in a wide variety of homes and deliver high customer satisfaction across a range of customer groups. It is also evaluating products and services that increase the appeal of heat pumps and identify optimal solutions for a wide range of homes.

The project is managed on behalf of the government by a consortium led by Energy Systems Catapult and including LPC Delta-EE and Oxford Computer Consultants. Three Delivery Contractors (DCs) were appointed in June 2020 to recruit consumers, survey properties, install heat pump heating systems and monitor their performance. The DCs are:

• E.ON: working with Newcastle City Council and Your Homes Newcastle in the Newcastle area;
• OVO Energy: working with Kaluza, RetrofitWorks, Parity Projects and SunAmp in the South East of England; and
• Warmworks: working with Changeworks in the South East of Scotland.

The project had a target to install heat pumps in up to 750 homes across Great Britain in a representative range of housing archetypes, with the majority on the gas grid. The project recruited participants from the public to go through a customer journey including home suitability survey and heat pump design.

This report provides insights and data from the home survey, design and installation stages of the project. It should also be noted that the findings in this report are in the context of the knowledge, skills and experience of the surveyors, designers and installers who carried out relevant stages of this project. The three DCs took different approaches to the project stages, and these differences impact the comparability of some results. There are also a few instances where the results are subjective as the associated questions may have been interpreted differently by contractors.

The aims of this report are to provide a view of:

• The homes involved in the project e.g. property type, age, size, etc,
• Types of heat pumps installed and additional measures required,
• Costs of installations,
• Barriers to heat pump installations, and
• Lessons from the home survey, design and installation stages.

Key points

Properties involved in the trial

Electrification of Heat successfully demonstrated a key aim of the project – that heat pumps can be installed in a wide range of domestic properties across the UK.

Heat pump types installed

Of the 742 heat pumps installed:

• 41% were low temperature air source heat pumps (ASHP),
• 33% were high temperature air source heat pumps,
• 21% were hybrid heat pumps,
• 1% were individual ground source heat pumps (GSHP) and
• 4% were shared ground source heat pumps.

Additional measures installed

• 93% of homes that had a heat pumps installed required at the replacement of at least one radiator.
• 81% of homes required a new thermal store, such as a hot water tank, either because the property had a combi boiler before and no thermal store, or because the original cylinder did not have a suitably sized coil for a heat pump.
• A small number of homes – 33 flats – had a heat battery installed instead of a hot water tank, due to lack of space.
• 15% of properties required energy efficiency upgrades – in the majority of cases this was loft insulation, and a few properties received cavity wall insulation or door replacements.
• A small number of properties – 27 homes – required measures to keep heat pumps within noise limits.
• Participants did not raise concerns around aesthetics.

Costs of heat pump systems installed

• Average total cost per property was about £14,800 including the heat pump unit, additional measures and installation. However the benefits of bulk buying and economies of scale should reduce costs.

Barriers to heat pump installation

• Only 12% of properties surveyed were considered unfeasible based on technical constraints.

The main non-participant barriers were:

• Practical – external or internal space constraints: eg. 8% of properties lacked of external space for an outdoor units and 5% of properties were too close to a neighbours to meet noise limits. Only 2% of properties lacked of internal space for a thermal store or larger radiators.
• Technical – heating capacity constraints: eg. 7% of properties needed a heat pump larger than products available for this trial to  meet property needs and 4% of properties had other comfort requirements that could not be met in this trial.
• Economic – cost of upgrades required: eg. 4% of properties were assessed to need measures too costly for how some DC’s set their project budget (eg. OVO set a cap of £15,000 per property).

Overcoming these barriers was explored in the project as far as possible. For example:

• Engagement with the local planning authority helped to facilitate discussions around noise and permitted development.
• Contractors spent considerable effort finding ways to minimise disruption for customers.
• The local DNO was engaged to try and speed up the processing of connection applications .

However, overcoming all barriers was not within the control of the project. For example, exploring solutions to microbore piping issues, such as installation of low loss headers, was beyond the scope of this project.

Lessons Learned

Design standards, tools and assumptions

Through the project it emerged that there are different understandings and interpretations of MCS standards and how to achieve compliance. Feedback from project delivery partners is that there is an overall industry trend towards surveyors being overly cautious in their design assumptions for calculating the heat demand of a property, leading to over-sizing of heat pumps. Questions also emerged as to whether manufacturer design tools should be accredited and for better industry understanding of MCS standards.

Manufacturer documentation and guidance

Guidance from manufacturers on installation of heat pump units can be lacking or inconsistent.

Customer expectation management

On average, heat pump installations took 2-4 days to complete by a team of two installers and one electrician, including the installation of new radiators and water tanks but excluding installation of any energy efficiency measures. To maintain customer satisfaction, DCs found it was important to discuss the potential disruptions early on in the engagement process, clearly communicate how long installers would be in their home, and provide an alternative heat source for the installation period.

DNO approvals

For properties where load checks were required by the local Distribution Network Operator (DNO), these checks sometimes took several months to complete, delaying heat pump installations. Lack of standardisation in decision-making and inability to handle batch requests within the DNO organisation was also reported as issues by some DCs. If these challenges are not resolved, DNO approvals could become a significant barrier to the mass roll out of heat pumps.

Best practice and recommendations

The report found that the sector has an opportunity to improve the delivery and consistency of the installation supply chain. This could be achieved by:

• Conducting a review of the design and installation requirements and guidance as well as the installer certification process such that it ensures high quality installations and increases consumer confidence in the industry.
• Offering support and training for domestic heat pump system designers and installers.
• Standardising the heating system design tools to ensure a consistent design standard.