Air Conditioning Cost by Room: Size and Price for Every Room (UK 2026)
What size air conditioning each room needs and what it typically costs to install in the UK — bedroom, living room, home office, loft conversion and more, with the £2,500 grant explained.
By Max Tuleberg · Founder, Vento · Last updated 24 October 2026
Founder of Vento. Worked on the tools before building the software.
Most single rooms cost around £1,500–£3,000 to air condition in the UK, supplied and fitted with one wall-mounted split. Several rooms on one system (a multi-split) typically cost around £3,000–£7,000+ in total. Below is the size each room usually needs and where it tends to land on price.
Size and cost by room
| Room | Example floor area | Indicative size | Typical installed cost | What to watch |
|---|---|---|---|---|
| Single bedroom | 7–10 m² | 0.7–1.5 kW | £1,500–£3,000 (single split) | Quiet indoor unit matters most. |
| Double bedroom | 11–15 m² | 1.1–2.3 kW | £1,500–£3,000 (single split) | The most common single-room install. |
| Main bedroom | 15–20 m² | 1.5–3.0 kW | £1,500–£3,000 (single split) | En-suite and dressing areas add to the area. |
| Home office | 8–12 m² | 0.8–1.8 kW | £1,500–£3,000 (single split) | Computers and screens add heat; size towards the top. |
| Living room | 18–25 m² | 1.8–3.8 kW | £1,500–£3,000 (single split) | Big windows or south-facing glass push it up. |
| Open-plan kitchen-diner | 25–35 m² | 2.5–5.3 kW | £1,500–£3,000 (single split) | Cooking and glazing add load; often 5 kW or more. |
| Loft conversion | 15–25 m² | 1.5–3.8 kW | £1,500–£3,000 (single split) | Sun on the roof makes lofts run hot; size at the top or above. |
| Conservatory / garden room | 12–20 m² | 1.2–3.0 kW | £1,500–£3,000 (single split) | Heavy glazing — usually needs well above the rule of thumb. |
Sizes use a common UK rule of thumb — roughly 0.1–0.15 kW of cooling per square metre — applied to example floor areas. Measure your own room and use the size calculator for a closer figure. Costs are indicative supplied-and-fitted ranges; long pipe runs, difficult access and premium brands push them up.
One room or several?
If you want more than one room cooled (or heated), ask about a multi-split: two to four indoor units running from a single outdoor unit, typically £3,000–£7,000+ in total. It is usually cheaper per room than separate systems because you only pay for one condenser and one set of external work.
Rooms that need more than the rule of thumb
- Conservatories and garden rooms — glass lets in far more heat than walls, so they can need well above the rule of thumb.
- Loft conversions — the roof takes direct sun all day; size towards the top of the range or above.
- South- or west-facing rooms with large windows — afternoon sun is the biggest single load in most UK homes.
- Home offices and kitchens — computers, screens and cooking all add heat.
For any of these, a proper room-by-room heat-load calculation beats floor area every time — it's what a good installer will do at the survey.
Can a grant cut the cost?
Possibly. If the system is an air-to-air heat pump — air conditioning used to heat your home as well as cool it — that can meet all of your home's space heating on its own and replaces your existing gas, oil, LPG or electric heating, a £2,500 Boiler Upgrade Scheme grant can come off the price in England and Wales. That usually means a multi-split or ducted system covering the home — one room on its own, or cooling only, doesn't qualify. See who qualifies for the grant.
What it costs to run
A modern inverter split is cheap to run for cooling in a UK summer — see our running costs guide for worked examples, or the running cost calculator for your own figures.
This guide is general information for UK installers, not legal or regulatory advice. Always check the current regulations and manufacturer instructions for your specific job.
Frequently asked questions
How much does it cost to put air conditioning in one room?
As an indicative 2026 guide, a single wall-mounted split for one room typically costs around £1,500–£3,000 supplied and fitted in the UK. A small bedroom sits at the lower end; a large, sunny living room, loft or conservatory towards the top. A single room on its own won't usually qualify for the £2,500 Boiler Upgrade Scheme grant, because the system has to heat the whole home.
What size air conditioner do I need for a bedroom?
Using the common UK rule of thumb of roughly 0.1–0.15 kW per square metre, a typical double bedroom of 11–15 m² needs around 1.1–2.3 kW. Wall-mounted units commonly come in sizes around 2.0–2.5 kW, so most bedrooms suit the smallest standard units.
Is it cheaper to air condition several rooms at once?
Usually, per room. A multi-split runs two to four indoor units from one outdoor unit and typically costs around £3,000–£7,000+ in total, which works out cheaper per room than separate systems because you share one condenser, one set of external works and one visit.
Why does a conservatory need such a big unit?
Because glass lets in far more heat than a solid wall. A conservatory can need well above the 0.10–0.15 kW per m² rule of thumb, so it should always be sized with a proper heat-load calculation rather than floor area alone.
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