Home office air conditioning
By Airva Editorial Team · Checked against published UK guidance · Updated
A home office is the one room in a house that is occupied for eight hours at a stretch, by someone who cannot leave, sitting next to equipment that generates heat continuously. It is also, in most houses, a converted box room or a spare bedroom that was never intended to be used that way — often the smallest room, frequently at the top of the house, and quite often facing the afternoon sun.
Two things separate a home office from a bedroom of the same size: the heat load is higher than you think, and you will be on video calls, so the noise specification matters for a different reason.
Count the equipment
Bedroom sizing assumes a sleeping body and little else. A home office adds a continuous internal gain that people routinely leave out of the calculation:
- A person working produces meaningfully more heat than a person sleeping.
- A desktop computer under load is a real heat source, and a gaming or workstation-class machine substantially so.
- Monitors, especially two or three of them, run warm all day.
- Docking stations, laptop chargers, a printer, network kit — individually small, collectively not.
- Lighting, if the room is poorly daylit and lit artificially all day.
None of these are enormous individually. Together, in a small room, they are frequently the difference between a unit that holds temperature and one that does not. In a box room with two monitors and a desktop, the equipment can rival the solar gain.
Noise, and the microphone problem
Bedrooms need quiet so you can sleep. A home office needs quiet for a different reason: your microphone will pick up the unit even when you have stopped noticing it.
- Specify on the low fan speed figure, as with a bedroom — a modern unit around 20 dB(A) on its quiet setting will not trouble a call.
- Size correctly so it runs on low. An oversized unit short-cycles, and the restart is exactly the sound a noise-gated microphone lets through.
- Keep the airflow off the desk. Air moving across you for eight hours is uncomfortable well before the room is cold, and it moves papers.
- Mind the position relative to the camera. A wall unit directly behind you is in shot on every call, which is a presentational rather than a technical point, but people care about it after the fact.
Our quiet air conditioning guide covers what the published figures mean.
The winter case is usually stronger
Most people come to this looking for summer cooling, and then find the heating half is what they use most.
A home office is typically one room needing warmth from 8am on a weekday, in a house whose central heating is either off during the day or heating the entire building for one occupied room. A reversible unit heats that room quickly, under its own control, at roughly a quarter of the running cost of the plug-in electric heater most home offices actually contain.
That is a stronger everyday case than cooling, particularly in a garden room or garage conversion with no wet heating at all. See heating and cooling for how it performs in cold weather, and note that a reversible system is also the version that keeps permitted development rights, since the right excludes units used solely for cooling [1].
Working from home is not a workplace duty
One thing worth clearing up, because it comes up: the HSE workplace temperature guidance — a minimum of normally 16°C, no legal maximum, with employers required to keep temperatures reasonable and provide clean fresh air [3] — is written for workplaces the employer controls. It does not translate into an obligation on your employer to air condition your spare room.
Some employers will contribute to home working equipment as a matter of policy. That is a conversation worth having, but it is a policy question rather than a legal entitlement.
Which room, and which system
| Situation | Notes |
|---|---|
| Box room or spare bedroom | The common case. Small load but concentrated; a 2.0–2.5kW unit usually suffices once equipment is counted. |
| Loft conversion office | Hottest room in the house and often the coldest in winter. The clearest case for a reversible unit. |
| Garden room | Usually no heating at all, so the winter case dominates. Needs its own electrical supply consideration. |
| Garage conversion | Often poorly insulated; check the fabric before sizing. |
| Corner of a living room | Cooling the whole room for one desk is inefficient — consider whether the room needs it anyway. |
Where the office is one of several rooms you want covered, a multi-split usually makes sense — with one caveat that matters here more than elsewhere. All rooms on one outdoor unit must be in the same mode. A home office that needs cooling from equipment heat while bedrooms want heating in spring or autumn is precisely the case where that constraint bites, and it may justify a separate single split for the office.
Cost and running cost
A single-room home office installation typically falls in the £1,500–£3,500 range for a wall-mounted split. Where the room is a garden building, add the cost of a suitable electrical supply if one is not already present. Our cost guide covers the extras that appear late.
Running cost is modest for cooling and more significant for heating — which, given a home office is used through the winter, is the number to look at. The running costs guide works both from the current Great Britain average unit rate of 26.32p per kWh [2].
Frequently asked questions
What size air conditioning does a home office need? Usually 2.0–2.5kW for a small room, but the calculation must include the equipment. A workstation and multiple monitors add a continuous load that floor-area sizing misses entirely.
Will it be quiet enough for video calls? Yes, if specified for it. A correctly sized modern unit on low fan speed is around 20 dB(A). The risk is oversizing, because the short-cycling restart is what a microphone picks up.
Is air conditioning tax deductible for home working? That depends on your employment status and how the room is used, and it is a question for an accountant rather than an installer. Do not assume it is.
Does my employer have to provide it? No. Workplace temperature duties [3] apply to workplaces the employer controls, not to your spare room. Some employers contribute as a matter of policy.
Should I just use a portable unit? For a few weeks a year, possibly. For a room you work in daily, a fixed system is quieter, more efficient and heats in winter — which a portable generally does not.
Can one system cover my office and bedrooms? Yes, on a multi-split — but every room shares one mode. If the office needs cooling while bedrooms want heat, a separate unit for the office is the better design.
Get it sized for what is actually in the room
Tell us about the office — size, floor, orientation and what equipment runs in it — and we will match you with one vetted installer who will count all of it: get an installer match.