Air conditioning in a listed building in London

The two consents

A listed building in England needs two different kinds of permission for air conditioning, and they are easy to confuse.

Consent	What it covers	Who decides
Listed building consent	any work that affects the building’s special architectural or historic interest, inside or out	the council, often with its conservation officer
Planning permission	external development, such as the outdoor unit	the council’s planning team

Normally a heat pump that also heats can go on a house without planning permission under Class G permitted development. But the Planning Portal is clear that permitted development rights do not apply to installations within the curtilage of a listed building. So for a listed house, the outdoor unit needs planning permission as well as listed building consent.

Listing covers the whole building, inside as well as out, and often later additions and boundary walls. A grade II listing is not just the front façade.

Islington’s listed terraces

Islington is one of the boroughs where this comes up most. Barnsbury, Canonbury and the squares around Highbury and Islington are lined with listed Georgian and early Victorian terraces, many split into flats. The council lists 42 conservation areas, and many listed buildings sit inside them. Our Islington area page covers the borough’s planning picture.

The same is true elsewhere in central London: Bloomsbury squares in Camden, stucco terraces in Kensington and Chelsea, and Georgian houses in Westminster. The Barbican Estate in the City of London is listed as well, so external alterations there are tightly controlled.

What conservation officers look for

Every case is judged on its own merits, but a well prepared application usually shows that the scheme:

• puts the outdoor unit where it cannot be seen from the street or from public spaces, typically in a rear lightwell, a lower ground floor area or behind a parapet on a rear roof
• avoids cutting through historic features such as cornices, panelling, shutters and decorative ceilings
• uses existing openings or later fabric for pipe routes where possible, such as a modern rear extension
• can be removed in future without lasting damage
• does not cause noise problems for neighbours

A heritage statement explains why the chosen routes cause the least harm, and a noise assessment shows the outdoor unit will not disturb anyone.

Practical design approaches

In a Georgian terrace, the plan often looks like this:

1. Outdoor unit at the rear, in the lower ground floor area or on the roof of a later rear extension.
2. Pipe route through a modern part of the building, a service cupboard or alongside existing pipes.
3. Indoor units placed in less sensitive rooms, or concealed in joinery such as bookcases or window seats, with discreet grilles.
4. Condensate drained to an existing waste pipe or with a small pump, avoiding new holes in historic walls.

Ducted systems can work in listed buildings where there is a later ceiling or a service void, but cutting new ducts through historic floors and ceilings is often refused. Our guide to ducted air conditioning explains how they work.

Flats in listed buildings

Many listed London houses are now flats. In that case you need:

• freeholder consent under your lease, often a licence for alterations
• listed building consent from the council
• planning permission for the outdoor unit

The freeholder may also want to see the conservation officer’s view before agreeing. Where an outdoor unit is not acceptable, a portable unit that does not touch the fabric may be the only option.

Getting the order right

1. Find the listing description on the National Heritage List and confirm what is listed.
2. Talk to the council’s conservation team about whether air conditioning is likely to be acceptable and where.
3. Get a survey and a design that works with the building.
4. Prepare drawings, a heritage statement and a noise assessment.
5. Apply for listed building consent and planning permission together.
6. Only start work once both are granted.

Who should do the work

As with any system, the refrigerant must be handled by an engineer with an F-gas qualification working for a certified company, listed on gov.uk. In a listed building, the installer also needs to follow the approved drawings exactly, since moving a pipe route or a hole by a few feet can breach the consent. Our home air conditioning page explains how we survey and plan installs, and our guide to conservation areas covers the rules for unlisted homes nearby.

Common reasons applications struggle

Most refusals and long delays come back to a few avoidable problems:

• a visible outdoor unit on a street elevation, a roof slope or a prominent side wall
• new holes through historic fabric where an existing opening or later wall could have been used
• surface mounted trunking across decorated rooms, cornices or panelling
• no noise evidence, leaving the council unable to judge the effect on neighbours
• vague drawings that do not show exactly where pipes, drains and cables will run

Each of these can usually be designed out at the survey stage. A slightly longer pipe run to a hidden rear position, a unit inside an existing service cupboard, or an indoor unit on a later partition wall rather than an original one can make the difference.

Cooling without fixed air conditioning

Where a fixed system is not acceptable, there are still ways to reduce overheating in a listed home. Internal shutters, which many Georgian houses already have, block a lot of sun if closed during the day. Secondary glazing, which often needs listed building consent itself, can help with both heat and noise. Ceiling fans and portable units need no consent if they do not touch the fabric. These will not match a split system on a 35°C day, but they can make a top floor bedroom bearable.