Bedroom
air conditioning
A bedroom is the hardest room in the house to get right, and not because it is difficult to cool. It is because you are asleep in it, which makes noise the specification and everything else secondary.
- Free survey and a fixed written price
- Sized from a calculation, not from the floor area
- One day on site for most single rooms
Brands we work with
A bedroom air conditioning unit costs 1,750 to 2,800 pounds fitted including VAT. A typical double bedroom of 14 square metres needs about 2.5kW, and the quietest wall units run at 19 dB(A), which is below the background level of a quiet room.
The single most common mistake in a bedroom is fitting a unit that is too big, and the reason it matters is noise rather than money.
What size a bedroom actually needs
Using the same model as the sizing calculator on this site: 0.14kW per square metre, adjusted for aspect, floor and glazing.
| Room | How it works out | Unit |
|---|---|---|
| Single bedroom, 10 m², north facing, ground floor | 10 × 0.14 = 1.40, less 10% for aspect | 2.0kW |
| Double bedroom, 14 m², east facing, first floor | 14 × 0.14 = 1.96, plus 5% for floor | 2.5kW |
| Double bedroom, 14 m², south facing, top floor | 1.96, plus 18% aspect and 10% floor | 2.5kW |
| Large bedroom, 20 m², west facing, large glazing | 2.80, plus 18% aspect and 18% glazing | 3.5kW |
| Loft bedroom, 16 m², south facing | 2.24, plus 18% aspect and 30% for the loft | 3.5kW |
Why an oversized unit is the thing that wakes you up
An inverter air conditioner is at its quietest when it is working gently and continuously. It reaches the temperature you asked for and then sits there, fan barely turning, compressor ticking over at a fraction of its capacity.
A unit that is too big for the room cannot do that. It pulls the room down to temperature quickly, stops, waits while the room drifts back up, and starts again. Every one of those restarts is a change in sound, and a change in sound is what wakes people, not a constant one. It also leaves the room clammy, because a system that runs in short bursts never runs long enough to take much moisture out of the air.
So the sizing on a bedroom is not a budget decision, it is a comfort decision, and it is the reason we would rather do the calculation than sell you the next size up.
The numbers worth asking a supplier for
Sound pressure at the lowest fan speed, in dB(A), for the indoor unit. The best wall units are 19 dB(A). Rustling leaves is about 20 and a quiet bedroom at night is typically 25 to 30, so a 19 dB(A) unit at sleeping distance is below the room it is in.
Sound pressure for the outdoor unit, at one metre, because that is the number a neighbour experiences. Domestic outdoor units sit between about 46 and 52 dB(A), and position and anti-vibration mounts change what arrives at a window more than the model does.
Both figures are published by every manufacturer for every model. If a quote does not name the model, it cannot be checked. There is more on outdoor noise, including what to do if a neighbour complains, on the noise page.
Where the indoor unit goes in a bedroom
Not above the bed and not pointing at it. Air discharged onto a sleeping person is the commonest reason somebody stops using a system they paid for, and it is entirely avoidable at survey.
The usual answer is the wall the bed head is on, discharging along the length of the room over the bed rather than down onto it, or the opposite wall high up with the vanes set flat. Where the room only allows one position, a unit with a good auto-vane and a comfort mode earns its money.
It also has to be somewhere the condensate can fall outward to a drain, and somewhere the filters can actually be reached, because a filter that needs a stepladder and moving the bed is a filter nobody cleans.
What it costs
| Scope | System | Installed price |
|---|---|---|
| Single bedroom | 2.0 to 2.5kW wall unit | £1,750 to £2,400 |
| Double bedroom | 2.5 to 3.5kW wall unit | £1,900 to £2,800 |
| Two bedrooms, one outdoor unit | 2 unit multi-split | £3,200 to £4,400 |
| Three bedrooms | 3 unit multi-split | £4,500 to £7,500 |
| Annual service | Any make | £95 plus VAT |
Every figure on this site is an estimate based on published UK market ranges and our own installation experience. It is not a quotation. The price you are given after the free survey is the price you pay.
Other rooms
Loft conversions
A loft conversion is reliably the hottest room in a London house, and it is hot for three reasons at once: the roof above it, the heat rising into it from the rest of the house, and insulation that was designed to keep warmth in during winter.
Loft conversionsConservatories
A conservatory is the one room where we will sometimes tell you not to buy air conditioning yet.
ConservatoriesHome offices
A home office is a small room with a person and several hundred watts of electronics in it, occupied for eight hours at exactly the time of day the sun is on the building.
Home officesSize any room
The calculator behind every figure on this page, in kW and BTU, with the working shown.
Sizing calculatorBedrooms: common questions
How quiet is air conditioning in a bedroom?
The quietest wall units run at 19 dB(A) at their lowest fan speed, which is quieter than rustling leaves and below the background level of most bedrooms at night. Most good units are between 19 and 24.
Whether you hear it in practice depends more on sizing than on the model. A correctly sized unit runs continuously and gently at that lowest speed; an oversized one keeps starting and stopping, and it is the change you notice.
What size air conditioning does a bedroom need?
A single bedroom of around 10 square metres is usually 2.0kW and a double of around 14 square metres is usually 2.5kW. A loft bedroom needs roughly 30 percent more than the same room downstairs, and a south or west facing room about 18 percent more than a north facing one.
There is a calculator that does this properly on the sizing page.
Will it dry the air out?
It will reduce the humidity, which in a British summer is usually the point. Cooling air below its dew point takes water out of it, and a room at 24 degrees and 50 percent humidity feels considerably better than the same room at 22 and 70.
It does not dry a room out the way a dehumidifier does, and if you find it too dry the usual cause is a set temperature that is lower than it needs to be. 22 to 24 overnight is comfortable for most people and costs much less to run than 18.
Can one outdoor unit do two bedrooms?
Yes, and it is usually the sensible way to do it. A multi-split runs two to five indoor units from one outdoor unit, which means one outdoor position to find, one set of brackets and one thing for a neighbour to look at.
The indoor units do not have to match, so a quiet flagship in the main bedroom and a plainer unit in the spare room is a normal and sensible way to spend the budget.
Free survey for a bedroom
We measure the room, do the heat load calculation properly, and give you a fixed written price with the model on it. If a smaller unit is the right answer, we will tell you.
Monday to Friday 9am to 7pm, Saturday 10am to 3pm, Sunday closed
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