Can You Install Air Conditioning in a Summer House? UK Guide

Can you install air conditioning in a summer house?

Yes, and for most garden rooms it is the single best upgrade you can make. A summer house with a wall-mounted air conditioning unit is usable all year round: heated cheaply in winter, cooled in July when a glazed garden building turns into a greenhouse, and kept dry in between.

We fit them in garden offices, gyms, studios and ordinary summer houses, and the job is usually one of the quickest we do.

Why not just an electric panel heater?

Most summer houses come with, or end up with, an electric panel heater, and it is the expensive way to do it. A panel heater turns one unit of electricity into one unit of heat. An air conditioning unit is a heat pump, and turns one unit of electricity into roughly three to four units of heat, so the same warmth costs a third or a quarter as much to run.

The bigger difference shows in summer. A panel heater does nothing for a garden room that hits 35 degrees behind its own glazing, which is exactly when you most want to use it. The heat pump cools it. It also dehumidifies, which protects the furniture, electronics and soft furnishings you leave in there over winter.

Sizing: small building, big glazing

A summer house is small in floor area, but floor area is not what drives the sizing. Garden buildings have a high proportion of glazing, lighter construction than a house, and often a felt or thin timber roof that soaks up the sun. All of that pushes the load up, so a summer house often needs a similar capacity to a much larger room in a house. Most garden rooms land on a 2.0 or 2.5 kW unit, and we confirm the sizing on the survey rather than guessing from the floor plan.

Construction and fitting

Timber-framed buildings take a wall-mounted indoor unit without any trouble, fixed through to the framing rather than just the cladding. The outdoor unit usually sits on a ground stand beside the building on a small paved or slabbed base, with a short pipe run between the two. On a well-built garden room the whole installation is normally done in half a day to a day.

The electrics

The one thing a summer house must have is a proper power supply: an armoured cable from the house on its own circuit, not an extension lead. If your building already has one, we connect to it. If you are still at the planning stage, or the building has no supply yet, Circuit Works' garden room electrics guide explains what is involved, and it is far easier to get the supply right when the building goes in than to retrofit it afterwards.

Planning permission

Garden buildings and their equipment generally fall under permitted development, and a small outdoor unit beside a summer house rarely needs a planning application, subject to the usual conditions on size, siting and noise. Listed settings and conservation areas have extra rules. Our planning permission guide covers the detail.

What it costs

A summer house installation starts from around £1,500 fully fitted, the same as a single room in a house, and the survey confirms the exact price in writing. Running costs are small: a 2.5 kW unit heating a garden office costs pennies per hour, and you only run it when you are in there.

Making the decision

If you are choosing a summer house now, it is worth planning the air conditioning and the electrics together, because the position of the power supply, the outdoor unit and the wall unit all interact. Tell us what you are planning and we will factor it into the survey. If the building is already up and wired, request a fixed-price quote and we will take a look.

Summer house air conditioning: common questions

Can it run off an extension lead?

No. It needs a proper supply from the house on its own circuit. The garden room electrics guide explains what that involves.

Will it heat the summer house in winter?

Yes. Heat pumps heat effectively even on cold days, at roughly a third to a quarter of the running cost of a panel heater, and keeping the building gently warm and dry protects everything stored in it.

Is a timber building strong enough for the unit?

Yes. The indoor unit is light and fixes through to the timber framing, and the outdoor unit sits on a ground stand rather than on the building.

What size unit does a garden room need?

Usually 2.0 to 2.5 kW, but glazing, construction and orientation matter more than floor area, so we size it on the survey.