A full UK classroom can overheat from thirty people, afternoon sun and computers long before the building fabric is the whole storey. A split can trim that temperature if it is sized for a full room and the air is not dumped on one row of desks. It does not bring in the fresh air a teaching room needs. Ventilation stays in the design. Survey occupancy, windows and controls before you buy a domestic unit for a space that fills and empties with the bell. Refrigerant work needs an F-gas certified company. If campus cooling exceeds 12 kW of effective rated output, inspection duties can apply.
Body heat when the room fills
Body heat from a full class is large, sudden and gone at the bell. Sizing from an empty room measurement at 8am will be wrong. Add sun on a west wall, a projector and a bank of laptops. A small bedroom-style unit may cope with a seminar room of six and fail a standard class. The pattern is spiky. You want a unit that can respond when the room fills, then set back at lunch and after school. Keep the throw off the front row and the teacher's neck.
Fresh air when the windows stay shut
Recirculating air conditioning tempers the same air. Classrooms also need a fresh-air strategy so the room does not go stale with the windows shut against noise or pollen. Mechanical ventilation, opening windows under supervision, or a system designed to do both jobs can sit alongside cooling. Closing every window because the split is on is how air quality slides. Staff workplaces fall under HSE temperature guidance, which does not set one maximum figure and still expects reasonable conditions. Pupil comfort is the school's welfare responsibility. A fitter can install cooling. They should not be asked to sign off teaching-space ventilation they have not designed.
Victorian height, listed walls and the playground
High Victorian classrooms stratify. A wall unit high on one side may cool the ceiling and leave the desks warm. The survey might prefer a different format or more than one indoor. Listed school buildings can need consent before any outdoor unit is fixed. Pipe routes should respect fire compartments between classrooms. Outdoor units at ground level need protection from play and a position that does not hum into the next classroom's open window. F-gas certification covers the refrigerant work. Choose a contractor used to working in term-time constraints, and plan a pre-term service after a holiday shutdown.
Frequently asked questions
Will air conditioning be enough if we keep the windows shut?
It may hold temperature and still leave the room stale. Plan ventilation as well as cooling. A split recirculates.
Can one unit cool a standard class of about thirty?
Only if the survey shows the capacity matches people plus sun and equipment. Many small domestic units are below that peak. Do not buy from floor area alone.
Do schools need TM44 inspections?
The duty follows effective rated cooling output over 12 kW, not the word school. GOV.UK inspection rules can apply once the site is over that line. A single small room can sit under it. Several rooms on one site often go over it.
Should pupils have the remote?
No. Controls should be simple for staff. A locked setpoint beats a remote in a drawer, with a setback at lunch and after school.
Does an IT suite use the same unit as the classroom?
Note IT suites and server cupboards separately. A seminar room of six and a standard class are different peaks, and a cupboard full of equipment is a different load again.
Core buying guides
Start with these high-intent guides, then dig into the rest of the library.
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.