Air conditioning for loft conversions: why do they get so hot?

Loft conversions are brilliant. Until summer arrives, at which point the lovely new bedroom, home office or guest room you spent a small fortune creating starts to feel like somewhere you could grow tropical fruit.

There are a few reasons loft rooms get particularly hot.

You are at the top of the house

Heat generated throughout the home rises. Your loft is waiting at the top to collect it.

The roof takes the full sun

Unlike rooms lower down the house, a loft conversion sits directly underneath roof surfaces that have been absorbing solar heat for hours.

Roof windows add more heat

Skylights bring in a lot of very welcome natural light. They also bring in heat, and a room with several roof windows can get warm surprisingly quickly on a bright day.

Opening a window only goes so far

Once it is genuinely hot outside, opening a window is not introducing a refreshing breeze. Fans help you feel cooler by moving air over your skin, but they do not lower the temperature of the room. That is the difference proper cooling makes.

What kind of system works well in a loft

A small wall-mounted split system is often ideal.

You have an indoor unit in the loft room connected to an outdoor unit positioned elsewhere on the building. The exact installation depends heavily on the roof and the property layout, so lofts are one of the cases worth getting properly assessed rather than guessed at.

The installer will be looking at:

• where the indoor unit can sit without blowing straight at the bed or desk
• the pipework route down through the property
• condensate drainage
• a sensible position for the outdoor unit
• roof structure and access

What if the loft is a home office

This is one of the cases where the sums are easiest.

If you are working in one room all day, it rarely makes sense to condition the entire house. You keep the office at a comfortable temperature and leave the rest of the property alone.

And because the unit provides heating as well as cooling, the same system warms the office in winter. That is particularly useful if everyone else is out and you would otherwise be running the central heating for one person sitting upstairs.

What if the loft is a bedroom

Then noise moves up the priority list alongside cooling capacity.

A good bedroom unit should have a quiet operating mode, and it should not be positioned so that you are sleeping directly beneath the airflow. The goal is simple: make the room boringly comfortable. You should not really notice the system once it is running.

Our bedroom air conditioning guide goes through noise levels, placement and sizing in more detail.

Can it be retrofitted to an existing loft

Often, yes.

You do not need to install cooling while the loft conversion is being built. An experienced installer can look at possible pipe routes, drainage and outdoor-unit positions and work out what is practical.

It is obviously easier to plan during the original conversion. But if your loft already exists and you have discovered that it reaches roughly the temperature of a greenhouse every July, this is usually still very fixable.

What it is likely to cost

Loft installations are priced on how awkward the work is rather than on the room itself. Pipe run length, outdoor-unit position, roof structure and access all matter, which is why some lofts are straightforward and some are not.

We do not publish average figures, because an average is wrong for most individual homes and a wrong number is hard to unpick later. What drives the price is covered in our guide to air conditioning installation costs, and the free Check gives you a range for your own property. If you are still weighing it up at all, is air conditioning worth it in the UK is the place to start.