Kitchen & Open-Plan Air Conditioning Cost UK (2026)
The open-plan kitchen-diner is the hottest room in most modern British homes: bifolds facing the garden, a glass roof, an oven and hob, a fridge and dishwasher, and a dozen people in it at once. It is also the hardest room to cool well from one wall. Here is what it costs to air condition properly in 2026, which unit layout suits which room, and the kitchen-specific points your engineer should raise.
What kitchen and open-plan air conditioning costs
All figures are 2026 supplied-and-installed prices from F-Gas certified engineers, including the outdoor unit, pipework and commissioning, with VAT.
| Room and layout | Typical installed cost | Notes |
|---|---|---|
| Small kitchen-diner, one larger wall unit | £2,000–£3,000 | Up to ~30 m², unit sized at the top of the single-split range to cover appliance heat |
| Open-plan extension, ceiling cassette | £2,000–£4,000 | Needs a ceiling void; four-way airflow covers long rooms and bifolds. See the cassette guide |
| Long or L-shaped space, two wall units on one outdoor unit | £2,800–£4,500 | Two-room multi-split pricing; heads at each end for even coverage |
Air Con Surrey 2026 baselines for Surrey and the South of England, VAT included. Whole-floor ducted systems (£7,000–£15,000+) are covered in the ducted guide.
The overall range for this room type is £2,000–£4,500. A kitchen-diner costs more than a living room of the same floor area because of the higher capacity needed, the longer pipe runs typical of rear extensions, and the higher chance of a cassette or two heads rather than one wall unit. For how a quote is built up see the installation cost guide.
Why kitchens need more cooling than the floor area suggests
A kitchen-diner has a bedroom's solar and fabric gains plus a set of deliberate heat sources, and on a Sunday lunchtime they all run at once.
- Cooking. An oven and hob can release a kilowatt or more into the room for an hour at a time; the extractor removes some of it.
- Appliances. Fridge-freezers, wine coolers and dishwashers reject heat continuously, and hardest on hot days.
- Glazing. Bifolds, roof lanterns and a south- or west-facing aspect bring solar gain far above a standard window.
- People and volume. Eight people at a table are roughly a kilowatt of heat, and vaulted ceilings hold far more air than the floor area implies.
A good engineer surveys rather than quoting off floor area alone. Under-sizing is the common kitchen mistake; a unit that copes in May and loses the fight in July is a poor investment at any price.
Which unit layout suits your room
One larger wall unit (single split costs) suits compact kitchen-diners up to around 30 m² where a short wall away from the hob is free; position it to blow along the room, not across the cooking zone. A ceiling cassette is best for long extensions with bifolds if there is a ceiling void, or one is being built: four-way airflow from the centre with nothing on the walls. Two heads on a multi-split is the pragmatic answer for L-shapes and no-void ceilings, a wall unit at each end or one in the kitchen and one in the adjoining snug or conservatory.
If you are still designing the extension, introduce the builder and the engineer early: a service void, a planned outdoor unit position and a pre-cored pipe route can take several hundred pounds off the price and make a cassette possible; the same goes for garden rooms. See our wall vs ceiling comparison.
Grease, smells, running costs and heating
Grease and filters. Airborne cooking oil is the enemy of any coil. Keep the indoor unit away from the hob, use the extractor, rinse filters monthly in summer and budget for an annual service at £75–£150.
Running cost. A 2.5 kW unit draws 0.7–0.9 kW, about 18–23p an hour at roughly 26p/kWh; a kitchen-sized 3.5–5 kW unit draws proportionally more at full tilt, then throttles back once the room is at temperature. See running costs for worked examples.
Heating. Glazed extensions are often the coldest room in winter. A modern unit is an air-to-air heat pump with a SCOP of 3.5–4+, so the same system heats the space efficiently on spring and autumn mornings. It is not eligible for the Boiler Upgrade Scheme (air-to-water only); see air conditioning vs heat pump.
Siting the outdoor unit. Rear extensions usually put the condenser in the garden: normally permitted development within siting and size limits, but conservation areas and listed buildings need consent, and a spot away from patio seating and neighbours' windows keeps everyone happy.
Sources & methodology
- Installed prices are Air Con Surrey 2026 baselines from engineer quotes across Surrey and the South of England, including VAT; access, pipe run and brand tier move individual quotes.
- Electricity at ~26p/kWh under the Ofgem cap from July 2026 (£1,663/yr typical dual fuel); heat-gain commentary reflects standard cooling-load practice, and a survey replaces rules of thumb.
- Installation must be carried out by an F-Gas certified engineer.
FAQs
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