Heat pumps in London: flats, close neighbours and existing heat networks

Permitted development rights for air source heat pumps in England extend to blocks of flats, but with tighter limits than for houses. The outdoor unit on a block of flats must not exceed 0.6 cubic metres, compared with 1.5 on a house, and only the first installation on a block is permitted development. After that, every further unit needs planning permission.

Leaseholders face a second hurdle: the lease almost always reserves the external walls, roof and gardens to the freeholder, so a unit needs the freeholder's consent regardless of planning. Converted Victorian houses split into flats are common across inner London and raise exactly these issues.

• house or flat, and who owns the external walls
• freeholder's consent, if you are a leaseholder
• whether another flat in the block already has a unit
• conservation area or listed building status
• distance from the unit to the nearest neighbour's window

Source: planningportal.co.uk

To qualify as permitted development, the installation must comply with the MCS 020a planning standard, which assesses noise at the nearest neighbouring window. In a dense terraced street, rear extensions and closet wings often put a neighbour's bedroom window only a few metres from the obvious unit position. A careful installer measures and calculates this, and may suggest a quieter model, an acoustic enclosure or another position.

Large parts of London are conservation areas, and each borough designates its own. In a conservation area, a unit on a wall or roof facing a road is not permitted development. Listed buildings have no permitted development rights for heat pumps at all. Before commissioning a survey, check your borough's conservation area maps; a rear position is usually the route that avoids an application.

Some London boroughs already have substantial heat networks. The government's heat network zone opportunity report for Southwark, for instance, notes residential networks including SELCHP that supply heat to around 17,000 properties, and identifies strategic zones at Thames Southbank, Camberwell, Elephant and Castle and around SELCHP itself.

The categories the government has consulted on requiring to connect in a zone are new buildings, large non-domestic buildings and communally heated residential blocks. If you own a house with its own boiler, zoning does not stop you fitting a heat pump. If you live in a council or housing association block already on a network, the heating is the landlord's decision.

Source: assets.publishing.service.gov.uk · gov.uk

The Boiler Upgrade Scheme applies in London through MCS-certified installers, and eligible low-income households in privately owned homes may qualify for the Warm Homes: Local Grant through their borough. Heat pump installations in homes are currently zero-rated for VAT.

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