Garden office
air conditioning
A garden office is a small insulated box with a glass front, which is exactly why it is too hot to work in by June and too cold by November. One small unit fixes both.
- Free survey and a fixed written price
- Sized from a calculation, not from the floor area
- One day on site for most single rooms
Accredited, and fitting the brands you know
Air conditioning we have fitted
Our own jobs, photographed on site. Real rooms, real outdoor positions, nothing from a catalogue.
Air conditioning
Outdoor unit on wall brackets
Above brick, isolator and cabling run tidy
Air conditioning
Condenser going up on straps
Lifted into a wall position, no scaffold
Air conditioning
Wall unit, commissioned
Set to 24 degrees and handed over
Air conditioning
Black wall unit in a sitting room
Chosen to sit with the room, not against it
Air conditioning
Ceiling cassette
Recessed flush into the ceiling
Air conditioning
Samsung Wind-Free
Cooling without a draught on the room
Air conditioning
Rooftop commissioning
Pressure tested and charged on gauges
Air conditioning
Outdoor unit at ground level
On paving beside the house, easy to service
Air conditioning
Black wall unit, running
Quiet enough for a bedroom
Air conditioning
One-way ceiling cassette
Only the grille shows
Air conditioning
Outdoor unit on paving
Against render, clear of the boundary
Air conditioning
Condenser high on a wall
On brackets where the ground was not an option
Most garden offices need a 2.0 or 2.5kW wall unit, which costs 2,400 to 3,200 pounds fitted including VAT. A larger or mostly glass garden room usually needs 3.5kW.
The question that decides the job is rarely the unit. It is whether the power supply already run down the garden can carry it.
Read the full guide: 6 sections, about 3 minutes
What size a garden office needs
Using the same model as the sizing calculator on this site. A garden room counts as a ground floor room; what pushes the size up is the glass and the use.
| Room | How it works out | Unit |
|---|---|---|
| Garden office, 8 m², east facing | 8 × 0.14 = 1.12, plus 12% office use | 2.0kW |
| Garden office, 10 m², south, glazed doors | 1.40, plus 18% aspect, 18% glazing, 12% office | 2.5kW |
| Garden room, 12 m², west, mostly glass | 1.68, plus 18% aspect, 30% glazing, 12% office | 3.5kW |
| Garden gym or studio, 15 m², south, glazed doors | 2.10, plus 18% aspect, 18% glazing, 5% use | 3.5kW |
The power supply is the real question
A garden room is usually fed by an armoured cable from the house to a small consumer unit inside it, and that cable was sized for the lights, a heater and a computer. Whether it can take an air conditioner as well depends on the cable, the protective device at the house end and what else is on it, and we check all three at the survey.
It is usually fine. A 2.5kW cooling unit draws well under a kilowatt of electricity while it runs, less than the panel heater it often replaces. Where the supply genuinely is too small, a new circuit is quoted as its own line rather than discovered on the day.
Where the two units go on a timber building
The indoor unit is fixed into the wall studs or onto a backing board, never into the cladding or the insulated panel alone. On a glass-fronted room with little solid wall, a floor-standing unit under the window is the usual answer.
The outdoor unit stands on a proper base beside or behind the building, with the pipe run a metre or two long, which makes a garden office one of the simplest installations we do. The condensate goes to a gravel soakaway or a drain rather than onto the decking.
Garden rooms often sit close to the boundary, and the outdoor unit has to meet the same permitted development conditions as one on the house, including the distance from the boundary. All eight conditions.
Winter is the better half
Most garden offices are heated with a plug-in or panel heater, which turns one unit of electricity into one unit of heat. The same air conditioner in heating mode turns it into roughly three to four, so a garden office that is used every working day through the winter costs noticeably less to keep warm.
For somebody who works from the garden all year, that usually matters more than the cooling does.
What it costs
| Scope | System | Installed price |
|---|---|---|
| Garden office up to about 10 m² | 2.0 to 2.5kW wall unit | £2,400 to £3,200 |
| Larger or glass-fronted garden room | 3.5kW wall unit | £2,550 to £3,500 |
| Floor-standing unit instead | Where the walls are mostly glass | Add £150 to £350 |
| Dedicated fuse board in the garden room | Where the existing one has no spare way | Add £450 to £850 |
Every figure on this site is an estimate built from the quotations we issued in 2026 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
Bedrooms
A bedroom is the hardest room in the house to get right, and not because it is difficult to cool.
BedroomsLoft 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 officesBasements
A basement is the one room in a London house that stays cool on its own, until it becomes a kitchen, a cinema or a gym with glass doors to a lightwell.
BasementsSize any room
The calculator behind every figure on this page, in kW and BTU, with the working shown.
Sizing calculator
Your estimate
£2,400to£3,200
Supplied, fitted, commissioned and certificated. Includes VAT.
Send this on WhatsAppPrice it for this room
One room, so the two things that move the number are how big it is and which kind of indoor unit you want.
Last step: where do we send your written price?
Every figure on this site is an estimate built from the quotations we issued in 2026 and our own installation experience. It is not a quotation. The price you are given after the free survey is the price you pay.
Garden offices: common questions
Do I need planning permission for air conditioning on a garden office?
Usually not, if the outdoor unit meets the permitted development conditions, which are about its size, where it sits and how far it is from the boundary.
The boundary distance is the one a garden room at the end of the garden most often fails. The conditions, in a table.
Can it run off the garden room's existing electrics?
Often, yes. A small unit draws less than most heaters. We check the cable, the protection at the house and the other loads at the survey before quoting.
If the supply is too small, the new circuit is a separate, visible line on the quote.
Is a portable air conditioner good enough for a garden office?
Rarely. A portable unit has to push its hot air out through a hose in an open window or door, which undoes the insulation the garden room was built with, and it is loud enough to be heard on every call.
A fitted unit is silent inside, and it heats in winter, which a portable cooler does not.
Will it keep the garden office warm in winter?
Yes. It is a heat pump and heats as well as it cools, down to well below freezing outside, and it costs far less to run than an electric heater.
Free survey for a garden office
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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