Working from home turns one room into an all-day heat load: you, a screen, and often a south or west window or a roof. A living-room split with the door open will not hold a box room upstairs. Survey the office itself, size that duty, and choose an indoor that is quiet on calls. Keep the outdoor unit off the wall you are sitting against if the microphone picks it up. The install is still an F-gas split, with the same planning and lease checks as any other room.
Eight hours in the room under the eaves
A few hours in a hot lounge is annoying. Eight hours in a small room under the eaves is the reason people buy. The survey should use that room's glass, the kit you run, and the fact the door stays shut so you are not cooling the landing. A 2.5 kW class unit is common for a small office and wrong for a glazed one. Let the numbers say so.
Do not buy a whole-house story for one desk. Multi-split is for when other rooms also need it. One well placed indoor is the usual home-working job. Survey the room you actually sit in. Energy Saving Trust describes air-to-air heat pumps. A living-room unit will only weakly cool an office upstairs, and it will stop holding the living room. Cool the room you work in.
The jet on your neck, and the condenser outside the window
A jet on your neck all afternoon is as useless as an undersized unit. Ask for the indoor on a wall that can sweep the room, not straight across the chair. WindFree-style or a very low fan setting is a comfort choice after the kW is right. Mitsubishi AY and similar quiet indoors are specified for this reason. Mitsubishi Electric publishes the sound data. Compare it. Do not invent a SEER winner. If the office is also cold on Monday mornings, say you want heating. A reverse-cycle split can take the edge off. It is not automatically the house heating system, and it should not be sold as an EPC trick.
You will run this unit on weekday afternoons, which is when neighbours are on calls too. Site it away from bedroom windows and away from the party wall if you can. Isolation mounts are not optional on a lightweight annex. A noisy indoor fan sits next to the microphone. A condenser outside the same window sits in the background. Choose a quiet indoor and a kind outdoor position. In England, the Planning Portal summary of Class G still requires that an air source heat pump used as permitted development is not used solely for cooling, and the other siting limits still apply. A home office does not get a special consent. Flats often still need permission and the freeholder. GOV.UK F-gas rules still apply. Working from home is not a domestic DIY exemption. Photos of the desk, the window and the outside wall, plus the hours you are in the room, are what the survey needs. If you rent, the landlord's consent comes first. The right indoor is the one that matches that room, not the one that matched a neighbour's lounge.
Frequently asked questions
Will the living room air conditioner cool my office if I leave the door open?
Only weakly, and it will stop holding the living room. Cool the room you work in, with the door closed, using a unit sized for that room.
What matters more on video calls, the indoor or the outdoor unit?
Both. A noisy indoor fan sits next to the microphone. A condenser outside the same window sits in the background. Choose a quiet indoor and a kind outdoor position.
Do home-office installs still need F-gas certification?
Yes for a split. Working from home is not a domestic DIY exemption.
Is 2.5 kW always enough for a home office?
It is common for a small office and wrong for a glazed one. Let the survey use that room's glass and the kit you run.
Does a home office get easier planning rules?
No. Class G still requires that an air source heat pump used as permitted development is not used solely for cooling, and the other siting limits still apply. Flats often still need permission and the freeholder.
Should I buy a multi-split for one desk?
Not unless other rooms also need cooling. One well placed indoor is the usual home-working job. Do not buy a whole-house story for one desk.
Core buying guides
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Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.