Summer term brings exams, sports days and some very warm classrooms. Many school buildings, from Victorian blocks to lightweight modular classrooms with big windows, struggle to stay comfortable in June and July. Air conditioning is one part of the answer, alongside shading, ventilation and how rooms are used.
This guide is for school business managers, bursars, heads and governors. It covers priorities, ventilation, timing, the legal checks on larger systems and how to brief an installer.
Which rooms to cool first
With a limited budget, start where heat causes the most trouble:
- Server and comms rooms. Network equipment runs all year and is the one place where overheating stops the whole school. Cool these on their own system. See our server room page.
- ICT suites. Rows of computers plus a full class make these some of the warmest rooms in the building.
- Exam and assessment spaces. Halls used for exams in the summer term, especially with large glazed areas.
- South and west facing classrooms, top-floor rooms and modular classrooms that heat up quickly.
- Medical rooms, staff rooms and offices used through the holidays as well as term time.
Before cooling a room, it’s worth checking the cheaper fixes: blinds or solar film on sunny windows, whether windows can open safely, and whether equipment is left running when it doesn’t need to be.
Ventilation and BB 101
The Department for Education’s Building Bulletin 101 gives guidance on ventilation, thermal comfort and indoor air quality in schools. It’s the starting point for any designer looking at overheating or fresh air in classrooms.
The key thing for governors to understand is that a wall-mounted or cassette air conditioning unit cools and filters the room air but doesn’t supply fresh air. A full classroom still needs ventilation. HSE says recirculating systems should be designed with fresh air inlets in its guidance on improving ventilation, and suggests CO2 monitors as a broad indicator: levels consistently above 1500ppm in an occupied room point to poor ventilation. Where fresh air is the real problem, mechanical ventilation with heat recovery may be a better first step.
Choosing the system
For a single classroom or office, a wall-mounted split is quick to install and easy to maintain. High-level positions and lockable or wired controllers stop the settings being changed by pupils. In rooms with suspended ceilings, cassettes keep units out of reach. For a whole block, VRF serves many rooms from shared outdoor units with central controls and timers.
Almost all modern systems are heat pumps, so they can heat as well as cool. That can help in rooms where the existing heating is poor, but it changes how you set up controls and timers with the site team.
Outdoor units need secure positions out of reach of pupils and balls, with clear access for maintenance. Pipes and condensate drains on external walls are protected or boxed in where they’re within reach.
Want it done properly? AirCon Doctor installs, repairs and services air conditioning and heat pumps across London and the South East, from our base in East Grinstead. We’re an F-Gas certified company and NICEIC approved. Get a fixed-price quote.
Planning around the school year
Installation work in occupied classrooms is disruptive, so most school projects are timed for the holidays. Summer is the main window, but it’s short and it fills up. A realistic timeline looks like this:
- Autumn or spring term: site survey, priorities agreed, quote and specification.
- Spring: approval through governors or the trust, and any planning or landlord questions answered.
- Holiday period: installation, commissioning and handover to the site team.
Schools set their own safeguarding requirements for contractors on site. Tell us yours at the start and we’ll confirm on the quote how the work will be arranged to meet them.
F-Gas, TM44 and records
The school or trust is the operator of its systems. Systems holding 5 tCO2e or more of refrigerant need leak checks at least every 12 months, with records kept. And if the total effective rated output of the air conditioning in a building is more than 12 kW, an accredited energy assessor must carry out an air conditioning energy inspection at least every five years. Several small units can add up past that threshold. Our TM44 page explains what’s involved.
A maintenance contract keeps servicing, leak checks and the asset list in one place, which helps when estates staff change.
Costs and budgeting
A single classroom or office with one wall-mounted split falls in our standard range of £1,200 to £2,200 + VAT. Multi-room, cassette and VRF projects are priced after a survey with a fixed-price quote, which you can use for budget approval. We can price in phases if you want to spread the work over more than one holiday. See our schools page and public sector page.
Quick answers
Is there a maximum temperature for classrooms?
There is no legal maximum workplace temperature. HSE says employers must provide a reasonable temperature and manage heat as a hazard. BB 101 gives design guidance on thermal comfort in schools.
Can air conditioning be installed during term time?
Sometimes, for one or two rooms that can be released for a day or so. Larger projects are best done in the holidays.
Does a school need a TM44 inspection?
If the total effective rated output of a building’s air conditioning is more than 12 kW, yes, at least every five years.
Related services
- School air conditioning
- Public sector air conditioning
- Server room air conditioning
- Ventilation systems and MVHR
- TM44 air conditioning inspections
More advice
- Air Conditioning for Offices: What You Need to Know
- Air Conditioning for Server Rooms: Complete Guide
- Can Air Conditioning Improve Air Quality?
- Air Conditioning Maintenance Contract: What It Includes and Is It Worth It?
- All advice
This guide is general information, checked against the sources linked on 30 October 2026. It isn’t legal, tax or financial advice. Rules, grants and product ranges change, so check the current position before you rely on it.