Air conditioning in listed buildings

Listed building consent comes first

If a building is listed, you need listed building consent from your local planning authority to alter it in a way that affects its character or appearance. Historic England says that carrying out unauthorised works to a listed building is a criminal offence, and that the authority can require unauthorised work to be reversed. Historic England’s guidance explains how to apply, and that there is no fee.

Works inside can affect a building’s character as much as works outside. So an outdoor unit on a wall, a hole for pipework, or trunking across a panelled room may all need consent. Your council’s conservation officer can tell you what applies to your building, and it is wise to talk to them before you commit.

Planning rules are separate

Listed building consent is not the same as planning permission. The Planning Portal explains that permitted development rights for air source heat pumps on houses do not apply within the curtilage of a listed building. In practice, an outdoor unit at a listed property will usually need a planning decision as well as consent. Cooling-only air conditioning is not covered by those permitted development rights anywhere, so check with the council. This is general information, not legal advice.

How we approach a listed building

We plan the least intrusive scheme that will work, and design it so it can be removed later without lasting harm. That usually means:

• Outdoor units out of sight: rear courtyards, enclosed yards, behind parapets on flat roofs, or in outbuildings, never on a principal elevation if we can avoid it.
• Pipe routes through existing voids: floor voids, roof spaces, cupboards, old service routes and chimney flues where suitable, keeping new openings to a minimum.
• Few, small openings: placed in later or less sensitive fabric, cored carefully and made good with materials agreed with the conservation officer.
• Discreet indoor units: ducted units in a loft or void with small grilles, floor-standing units or units hidden in joinery, rather than wall units on historic plaster.
• Reversible fixings: into mortar joints rather than historic brick or stone, so the work can be undone.

What we provide for the application

After the survey we can supply a written description of the proposed works, the equipment data, outdoor unit size and position, pipe routes, the number and size of openings, and noise data from the manufacturer. Photos and a marked-up plan help the conservation officer understand what is proposed. Many owners use a heritage consultant or architect to prepare the application itself, and we work with them on the technical detail.

Old walls, damp and condensation

Historic buildings were built to breathe. Solid walls with lime mortar and plaster manage moisture in a different way to modern cavity walls. We avoid cement-based sealants on lime, route condensate drains so water never runs into old walls, and take care with insulation around pipework. Air conditioning dries room air as it cools, which is usually helpful, but sudden swings in temperature and humidity can stress old timber and finishes, so we set it up for gentle, steady running.

Hotels, offices and churches in listed buildings

Many listed buildings are hotels, offices, shops, pubs or places of worship. Commercial projects follow the same consent process, and often need careful phasing so the building can stay open. See hotel air conditioning and our guide to churches and village halls.

Heat pumps in listed homes

Air-to-air heat pumps can heat as well as cool, and some listed homeowners use them to replace oil or electric heating. If you are considering a grant, the Boiler Upgrade Scheme has strict conditions, including that an air-to-air system replaces fossil-fuel heating and meets the full heating demand, installed by an MCS certified installer. We are MCS certified and can tell you whether your project could qualify.

Conservation areas

A building does not have to be listed for its setting to matter. In conservation areas, the Planning Portal says a heat pump outdoor unit must not be installed on a wall or roof that fronts a highway, or nearer a highway than the building, if it is to be permitted development. Article 4 directions can remove permitted development rights altogether in some areas. We look at these rules for your address and plan unit positions with them in mind. The council has the final say, so check with them before work starts.

Time and cost

Listed building work takes longer, mainly because consent can take weeks and the install itself is slower and more careful. The price reflects the scheme, so we give a fixed-price quote after the survey once the approach is agreed. We cover listed buildings across London and the South East, from town houses and cottages to hotels, offices and churches, and we are happy to meet your conservation officer or heritage consultant on site.