What it is and how it works

An air conditioning system moves heat rather than making it. Outdoors sits a condensing unit with a compressor. Indoors sit one or more fan units. Refrigerant circulates between them, carrying heat out of the building in summer and, when the cycle is reversed, into it in winter.

Commercial installations come in three shapes.

Split. One outdoor unit to one indoor unit. Simple, cheap, right for a single room, a shop or a comms room.

Multi-split. One outdoor unit serving several indoor units. Fewer things on the outside wall, which matters where space or appearance is constrained.

VRF. Variable refrigerant flow, for larger buildings. One outdoor system serves many indoor units, each controlled separately, with the refrigerant flow varied to suit what each zone is asking for. Heat recovery versions take heat out of a zone that is too warm and put it into one that is too cold at the same time, which is why they suit buildings with a sunny side and a shaded side.

Which one is right comes out of the heat load calculation, not the other way around.

Sizing, and why the survey matters

Oversized equipment is the most common fault we find on commercial sites. A unit that is too big cools the room fast, switches off, lets it drift, and switches on again. That short cycling wastes power, wears the compressor and leaves the room feeling uneven.

We calculate the heat load room by room: glazing area and orientation, occupancy, lighting, equipment, insulation and air movement. Then we size to that. The same survey checks the incoming electrical supply, because cooling is load, and on some sites the supply is the binding constraint rather than the space.

F gas and what you take on

Owning air conditioning that uses F gases carries duties, and they run for as long as you own the equipment.

Equipment holding F gas equivalent to 5 tonnes of CO2 or more must be leak checked at least every 12 months.
At 50 tonnes of CO2 equivalent or more, at least every 6 months.
At 500 tonnes or more, at least every 3 months, and an automatic leak detection system must be fitted.
Fitting automatic leak detection doubles the interval allowed between checks.
Hermetically sealed equipment containing less than 10 tonnes of CO2 equivalent is not subject to leak checks.

Whether your system crosses a threshold depends on the refrigerant and the charge, not on the size of the building. We set the answer out in writing at the design stage so the ongoing cost is visible before you buy.

Figures reviewed 20 September 2026.

Cooling with the rest of the building

The strongest reason to think about cooling and generation together is timing. Cooling load and commercial solar output peak on the same bright afternoons, so the roof covers the part of the year the running cost is worst. Battery storage carries that into the evening for a building still occupied at 7pm. Where the building needs heating more than cooling, a commercial heat pump is the other side of the same question, and we will say which one your building actually needs.

Pros and cons

Pros

The same equipment cools in summer and heats in winter, so one system covers the year
Demand peaks on bright hot days, which is exactly when a solar roof produces most
Zoning lets a server room, a shop floor and an office each hold their own temperature
Modern inverter-driven units modulate rather than switching on and off, which cuts running cost
Heat recovery VRF can move heat from a room that is too warm to one that is too cold

Cons

The standard rate of VAT applies to a commercial installation
Equipment above the F gas thresholds brings a legal duty to leak check it and keep records for as long as you own it
Outdoor units need somewhere to go, and on some buildings that needs planning permission or the landlord's agreement
Noise from outdoor units is a real constraint on a town centre or mixed-use site
Badly sized systems short cycle, cost more to run and wear out sooner, so the heat load survey matters
Cooling adds electrical load, so the incoming supply has to be checked before the design is fixed

Who it suits

Offices, shops, salons and restaurants that need comfort cooling through the summer
Server rooms, comms rooms and anywhere with equipment that has to stay cool all year
Buildings with rooftop solar looking for daytime load to use it on
Sites being refurbished, where the pipework and cabling can go in with everything else
Landlords fitting out a unit to let

What is included in a Bespoke installation

A room-by-room heat load calculation, not a guess from floor area
A survey of the incoming supply, the distribution board and the spare electrical capacity
Agreed positions for indoor and outdoor units, with the noise and planning position set out
Supply and installation of the units, pipework, drainage, controls and electrical connection
Commissioning, the controls explained to whoever will use them, and the handover pack
The F gas position for your system in writing, including whether it needs leak checks and how often

Frequently asked questions

Does air conditioning also heat the building?

Yes. A modern air conditioning unit is an air-to-air heat pump running in reverse, and it heats as well as it cools. In many commercial buildings it is the cheaper way to heat a space in shoulder seasons, because it moves heat rather than burning fuel to make it.

Do we have to have the system leak checked?

It depends on the refrigerant charge. Equipment holding F gas equivalent to 5 tonnes of CO2 or more must be leak checked at least once every 12 months, rising to every 6 months at 50 tonnes and every 3 months at 500 tonnes. Fitting an automatic leak detection system doubles the interval. Hermetically sealed equipment below 10 tonnes of CO2 equivalent is exempt. A single split in an office is often below the threshold, a VRF system across a building usually is not. We tell you which side of the line your system falls before you order it.

Do we need planning permission for the outdoor units?

It depends on the building, where the units go and whether the site is in a conservation area or is listed. Units on a flat roof behind a parapet are a different question from units on a street frontage. We give you the position for your building at the survey, and if an application is needed we say so before the quote is signed.

Can it run from our solar?

It is one of the better matches. Cooling demand rises with sunshine, so the load and the generation peak on the same afternoons. With commercial solar on the roof, a large part of the summer running cost can come off the array rather than the grid.

Is there 0% VAT on commercial air conditioning?

No. The zero rate for energy-saving materials applies to residential accommodation and buildings used solely for a relevant charitable purpose. Commercial premises are charged the standard rate, which a VAT registered business usually recovers in the normal way.