Retrofitting cooling into period and listed buildings

Consent comes first

Before any design work:

• Listed buildings require listed building consent for works affecting character, which includes external plant and frequently includes internal routing through historic fabric. Unauthorised works to a listed building are a criminal offence, and this is not an area to proceed hopefully.
• Conservation areas may have permitted development rights restricted, including by article 4 directions. Check with the local planning authority for your specific property.
• Even where permitted development applies, the conditions on size, siting, height and noise still have to be met.
• Some buildings have other designations – national park, area of outstanding natural beauty – with their own implications.

The practical approach with a listed building is to speak to the conservation officer early and informally, with a proposal that shows you have thought about minimising harm. That conversation is far more productive than submitting an application and being refused.

Reduce the load before you add plant

Frequently the most effective intervention in an older building is not cooling at all. Period buildings are often better at managing heat than people assume, and the problems are usually specific.

1. External shading. Shutters, awnings, blinds outside the glass, or a tree. Dramatically more effective than internal blinds, which absorb heat after it has already entered. Many period buildings originally had shutters and losing them is a real change in behaviour.
2. Solar control film or secondary glazing with a solar control coating. Secondary glazing is frequently acceptable in listed buildings where replacement windows are not, and it helps in winter too.
3. Night ventilation. Older buildings with high thermal mass cool overnight if you open them up, and hold that coolness through the following day if you close them up in the morning. That was how they were designed to work, and it still works.
4. Loft insulation, where the rooms that overheat are directly under the roof – which they usually are.
5. Reducing internal gains – equipment, lighting, occupancy where possible.
6. Ceiling fans, which are quiet, cheap, use very little electricity and make a room feel several degrees cooler through air movement.

Doing these first frequently reduces the cooling requirement enough that a smaller, less intrusive system will do – which makes everything else easier, including the consent conversation.

Routing, which is the real problem

Refrigerant pipework, condensate drainage, power and control cabling all have to get from the indoor unit to the outdoor unit. In a modern building this is straightforward. In a period building it is the whole job.

The single most useful thing at survey is a proper look at what voids and redundant services the building already has. Period buildings are full of them, and using one is both cheaper and far more likely to get consent than creating a new one.

Indoor unit choices for period interiors

• Ducted units, concealed in a ceiling void, a cupboard or a loft, with only a discreet grille visible. The best answer aesthetically where there is any void to use, and it is what conservation officers prefer.
• Floor-mounted consoles, which sit at skirting level and read more like a radiator than a piece of plant. Also better for heating.
• Slim wall units where nothing else works, positioned to be as unobtrusive as possible.
• Cassettes, where there is a suspended or accessible ceiling – rare in period domestic property.
• Colour and finish can sometimes be specified to blend rather than contrast.

Whatever the type, position matters for both appearance and performance – and a unit sited for appearance alone that distributes air badly will be disappointing.

The outdoor unit in a sensitive setting

Usually the most contentious element, and the one a planning or conservation officer looks at first.

1. Rear or concealed elevations rather than anything visible from a highway or a public vantage point.
2. Ground mounted and screened by planting at a distance that maintains airflow clearances – planting is far more acceptable than a built enclosure.
3. Within an existing outbuilding enclosure, where airflow can genuinely be maintained.
4. Behind an existing wall or outbuilding, using what is already there.
5. Not fixed to original fabric where a later structure is available.
6. Colour-matched where visible.
7. Noise considered, because period properties are frequently close to neighbours in historic street patterns.

A proposal that demonstrates the outdoor unit is invisible from any public view, reversibly fixed, and inaudible at the boundary is a proposal with a good chance.

Practical realities of period buildings

• Nothing is square or standard. Allow more time.
• Walls are thicker, which affects core drilling and pipe runs.
• Lath and plaster does not behave like plasterboard and needs care.
• There may be asbestos in later alterations, particularly mid-twentieth century work.
• Electrical supplies are frequently marginal and may need attention.
• Floors may be original and should not be cut into casually.
• Structural timber must not be notched or drilled without proper consideration.
• Surprises are normal – previous alterations, blocked voids, unexpected structure.

The right contractor for a period building is one who has worked in them, who will discuss routes before drilling anything, and who understands that a reversible solution is worth more than a tidy one.