If you only cool one room, make it the bedroom. Poor sleep is the thing people complain about most during a heatwave, and loft conversions and south or west-facing bedrooms can stay warm long after the evening has cooled down outside. Here's how to get bedroom air conditioning right.

Why bedrooms overheat

  • Heat rises. Upstairs rooms collect warm air from the rest of the house.
  • Roofs soak up sun. Loft rooms under a slate or tile roof can be several degrees warmer than the floor below.
  • Afternoon sun. West-facing windows let in the most heat just before bedtime.
  • Modern homes hold heat. Well-insulated, airtight new builds, such as those on newer estates around Droitwich, Worcester and Evesham, are very good at keeping heat in, including heat you'd rather lose in summer.

Quiet matters most

Bedroom units are chosen for how quiet they are. Manufacturers rate many modern wall units at around 19 to 22 dB(A) on their lowest fan setting, depending on the model. Look for a model with a night or quiet mode, a display you can switch off, and a gentle airflow setting. Portable units can't match this. We explain why in our portable vs fitted guide.

The outdoor unit matters too. It should sit away from your bedroom window and your neighbours' windows, both for comfort and to meet the permitted development noise limit.

Getting the size right

Most bedrooms need a unit of around 2.0 to 2.5 kW, but it depends on the room. A bigger unit isn't better. An oversized unit cools the room too quickly, switches off and on repeatedly, and doesn't remove humidity well, which leaves the air feeling cold and clammy. Each unit should be sized from the room's dimensions, windows and aspect.

Where the indoor unit goes

  • High on a wall, usually above or opposite the door, so cool air spreads across the ceiling before settling.
  • Not blowing directly onto the bed. Most units have adjustable louvres, but placement comes first.
  • On or near an outside wall where possible, which keeps the pipe run short and neat.
  • With a sensible route for the condensate drain, either outside by gravity or via a small, quiet pump.

Setting it for sleep

Pre-cool the room for an hour before bed, then let it hold at around 20 to 23°C overnight. Use sleep mode, which raises the target temperature slightly through the night. On muggy nights, dry mode on its own can make the room comfortable while using less energy.

What it costs to run

Once the room is down to temperature, a typical bedroom unit draws a few hundred watts. Our costs guide shows how to work out the cost on your own tariff, with a worked example.

Two bedrooms, one outdoor unit

If you want to cool more than one bedroom, a multi-split system can run two or three indoor units from a single outdoor unit. It's tidier, and on a semi or terraced house it keeps you within the one-unit permitted development limit.

Send us an enquiry and we'll pass it to an independent local installer, who can recommend a suitable unit after a survey.