Loft Conversion Air Conditioning

Loft conversions are often the hottest rooms in the house. The roof takes the full force of the sun, and roof windows let in strong light for much of the day. Warm air from the rest of the house also rises into the room. A loft bedroom can stay warm well into the night.

Why Loft Rooms Overheat

• Heat through the roof. The roof is in the sun all day, and heat builds up through the afternoon.

• Roof windows. Windows set into the roof slope face the sky, so they catch more sun than ordinary windows.

• Rising warm air from the floors below.

• Limited ventilation. Roof windows can be hard to leave open at night, and opening them does little on a still, warm night.

External blinds on roof windows help a great deal, and we suggest them as a first step. When they are not enough, air conditioning is the reliable answer. Our guide on how to cool down a room covers the simple measures first.

Which Type of Unit Suits a Loft?

• Wall-mounted units are usually the simplest choice. They often go on a gable wall or a straight section of wall below the slope.

• Floor-standing consoles sit low on the wall, so they suit rooms where the sloping ceiling leaves little space higher up. They fit neatly against the low wall under the eaves.

• Ducted units sit out of sight in the eaves or a void, with only grilles visible in the room. They need space and are best planned during the conversion itself.

Wall units need clear space above and around them for airflow, which is not always available under a sloping ceiling. We check this at the survey and agree the position with you.

Where Does the Outdoor Unit Go?

Options include a bracket on the gable wall, a flat roof or the ground, with the pipework run neatly down the outside of the house or through the eaves. Under permitted development in England, an outdoor unit cannot go on a pitched roof, and on a flat roof it must be at least 1 metre from the edge.

Long pipe runs are possible, within each manufacturer's limits. For example, Mitsubishi Electric allows up to 20 metres of pipework between the outdoor unit and an MSZ-LN25 indoor unit, with up to 12 metres of height difference.

What Size Unit Does a Loft Room Need?

Loft rooms usually need more cooling than a room of the same floor area downstairs, because of the heat coming through the roof and windows. A typical loft bedroom needs 2.5 to 3.5 kW, and a large loft with several roof windows may need more. We calculate the right size for each room at the survey. See our guide to what size air conditioner you need.

Planning a New Loft Conversion?

If you are still planning the conversion, talk to us early. It is much easier to run pipework, a condensate drain and the electrical supply most systems need before plastering and decorating. A ducted unit is only practical if the space is planned in.

Heating in Winter

Loft rooms can be hard to heat from the existing radiators. The same system heats the room efficiently in winter, controlled separately from the rest of the house. Read more about air conditioning as a form of heating.

What Does It Cost?

As a guide, one room typically starts from around £2,500. Lofts with long pipe runs, a floor console or a ducted unit may cost more. We give you a clear written quote after a free survey, and most single-room systems are fitted in a day.

Frequently Asked Questions

Do I need planning permission?

Usually not for a house in England. The outdoor unit must not be on a pitched roof, must be at least 1 metre from the edge of a flat roof and must meet the size and noise limits. Listed buildings and some conservation areas follow different rules. See our planning permission guide.

Can one unit cool the loft and the floor below?

Not reliably. Each room works best with its own indoor unit. A multi-split system lets you put a unit in each room from one outdoor unit.

Will the unit be noisy in a loft bedroom?

No more than in any other bedroom. The quietest wall units are rated at 19 dB(A) on their lowest fan setting. See our guide to bedroom air conditioning.

Call 01772 288651 or use the form below to book a free survey. We will measure the room, recommend the right system and give you a clear written quote.

Last updated: November 2026.