Around 15% of homes across Great Britain are flats, so it’s important that they’re included in the transition to clean heat. Nesta is finding out if the process of getting an air source heat pump installed in your own flat is any different from installing one if you lived in a house.

Surprisingly, there are some significant differences. This is partly because most flats are owned by leasehold, subject to freeholder consent, and partly because a lack of outdoor space and proximity to your neighbours can make it difficult to position your heat pump without needing planning permission.

We recently published our report identifying barriers to heat pump adoption, which set out some of the challenges any homeowner faces when they want to install a heat pump. 

This project draws out the additional challenges that flat owners will come across on their journey to installing a heat pump. Even though there will be some constraints in terms of tighter spaces, the issue we’re looking at here that’s significantly different for flats is the process of approval, which includes planning permission and freeholder consent.

Before we started this project, we looked at how flats are currently heated. We found that a significant number of flats in low-rise buildings were dependent on fossil-fuel heating systems. Low-rise blocks and converted flats are also more likely to have an individual heating solution that could easily be changed, without needing the whole block to upgrade. We found that many higher-rise blocks are either using (or are better suited to) a shared system, or they are already using electric heating, which has the potential to be low-carbon. So we’re focusing on low-rise blocks of flats, up to around four storeys, and maisonettes.

This project will delve into the rationale behind the extra requirements that apply to flats to see if the rules can be simplified. We think some things could change at national government level, whether that’s the UK, Wales or Scotland’s rules. We’re going to develop some theories around this and test them out with people who own or manage flats.

We think some other things could be made easier more locally, where planning authorities could choose to take a different approach, such as the Royal Borough of Kensington and Chelsea has done in simplifying the approval process for upgrading windows in conservation areas.

This project is all about making low-carbon heat an easier option. This will help us to reach our mission goal of significantly reducing carbon emissions from our homes. We’ve hit on a few things which are getting in the way, and we’ve split them into three strands:

Permitted development rights (PDR)

• If you can pass the tests for space, noise and line of sight, it’s possible to put in a heat pump without needing to make an application for planning permission. We want to know how likely it is for flats to pass these tests.
• Under current rules, only one heat pump is allowed per block under permitted development rights. We want to test some theories about when more than one should be allowed.

Full planning applications

• If you own a flat, making a planning application for anything requires a tedious amount of additional work ,including potentially costly independent assessments on things like flood risk. We think that this is irrelevant for heat pumps and want to make the application process more proportionate. 

Freeholder consents

• A lease for a flat usually specifies that the freeholder must give their consent for any works on the flat. Sometimes their neighbours within the block of flats own a share of the freehold. So it could mean having to persuade everyone in your building. We’re hoping to understand what influences those decisions.

We approached these three strands in different ways. 

To test the practicality of the permitted development rights tests, we worked with real-life flats and their owners. We looked for a good selection of the most common types of low-rise flats across Great Britain. Using a combination of calculations, we can make using simple software, and the in-person calculations of the people who live in the flats, to work out the likelihood of achieving a pass. 

This exercise identified where it’s more likely a heat pump can be located. It also helped give an indication if it’s more likely for flat owners with a garden, for example, than it is for others, such as those on floors above ground.

We also plan to work with some of these flats to calculate the impact of installing two heat pumps on the same block. 

Finally, worked with a selection of leaseholders and freeholders to explore the tensions with lease requirements. Our aim was to identify what could change, for example, varying the conditions of leases or changing how the freehold is managed or controlled. What we hope to achieve is well-informed, sound advice for both leaseholders and freeholders to help guide those conversations and influence decision-making opportunities.

 To get a sense of what drives decision making, we held three focus groups with the freeholders of leasehold flats. These were a combination of agencies, individual landlords and leaseholders themselves who had a shared freehold with their neighbours. We asked them about the sort of requests they get to make modifications to the property and how frequently those are for green upgrades. We also asked them how they deal with those requests, or hypothetically how they would deal with them if they’ve not had one yet.

Across the three focus groups, we found that leaseholders don’t often ask for green upgrades from their freeholders but the focus group participants reported being increasingly aware of green upgrades  and curious about them. Most commonly, participants cited conversations with leaseholders around insulation and EV charging points. 

We explored heating system upgrades with participants, focusing on air source heat pumps. Responses from freeholders ranged from not knowing what they were through to those that had their own installed at home. Freeholders told us that when something comes up that they know little about, their first instinct is to get hold of information about it, searching online, asking friends and family or speaking with their trusted tradespeople. 

A key driver for decision making here is uncertainty. Freeholders told us they needed some assurances that the work would be done well, professionally and leave no mess for them to clean up afterwards.

We spoke with participants about current planning rules which only allow for one air source heat pump to be installed on a block of flats under permitted development rights. This prompted an interesting discussion about how they manage their portfolio of properties. A key driver for decision making here is fairness and being able to support all leaseholders in the same way. Most freeholders pushed back against the idea of first-come-first-served when it comes to only permitting the first flat to install a heat pump without a planning application.

What was clear from the discussions across all three groups was that the better prepared the leaseholder was with trusted information or advice and assurances around risk and liability, the easier the freeholder would find it to make a decision. Even though most said they would also seek their own independent advice too.

With freeholder consent in place, the installation of a heat pump at a flat must still comply with planning regulations. It is possible to do this within permitted development rights provided the heat pump can meet all the requirements around location, noise and visibility.

We ran a practical experiment to assess which characteristics might make it easier to comply. Using the Carno installer software app, we visited a range of flats to test whether some could pass in the same way as a house could, if it has sufficient outdoor space. We looked at flats with back gardens and courtyards at ground level, and terraces above ground floor and found that they could pass the standard MCS020a assessment which is measured one metre in front of the neighbour’s nearest habitable window. 

We were unable to identify noticeable opportunities in denser urban settings as it is less clear where a heat pump could be positioned and the necessary distance from habitable rooms often isn’t there. It is worth seeking advice from a professional installer as all properties are different. It will also not be possible to install a heat pump on a flat under permitted development rights regardless if there is already a heat pump installed on the block.

We want to dive deeper into the permitted development rules that only allow one heat pump per block of flats. We plan to look at this across a range of archetypes. To do this we will work with an acoustician and a professional heat pump installer. 

We’re testing two things: where can you put a heat pump if you don’t have garden or terrace space and what happens when you have more than one heat pump on the block of flats, can you still pass the tests for location, noise and visibility?

We’d like to use this information to determine whether the ‘one heat pump per block’ rule should be re-evaluated.

We’re also interested in learning more about the history of planning decisions for air source heat pumps in GB. Using AI tools, we’ll be interrogating almost all previous planning applications that have been submitted. We’d like to know how many of these were for flats, what was involved in the application process and the outcome.

Here we’re exploring two more things: whether planning applications for flats are disproportionately onerous in practice and the conditions that are placed on flat owners before they are granted planning permission.

We’d like to use this information to build a case for simplifying the planning process for flat owners.