Business air conditioning

Commercial air conditioning differs from domestic in three ways that decide how a project runs, and all three surprise people.

Planning permission is usually required. The permitted development right that lets a householder fit an outdoor unit applies to domestic premises. Part 14 of the GPDO provides non-domestic classes for solar, ground source and water source heat pumps — but none for air source [2]. For most business premises, an external condenser means an application, and that application has a timeline you need to plan around rather than discover.

The compliance duties recur. F-gas leak checks at intervals set by refrigerant charge, and a statutory air conditioning inspection every five years above 12 kW combined output, for the life of the equipment [1][3]. A domestic install ends at commissioning. A commercial one starts a calendar.

The building sets the price, not the floor area. Plant access, out-of-hours working, ceiling type and electrical capacity move a commercial quote far more than square metres do, which is why these projects are priced from a survey rather than a list.

Start here: which project is this?

The right first page depends less on your sector than on the shape of the job.

• Fitting out a new space, or a space with none. Sequence matters more than equipment: new installation sets out the order that keeps a project on programme. Check electrical capacity early — supply, not floor area, is what most often forces a redesign.
• The existing system is failing, ageing or expensive to run. Replacement covers when a repair is the false economy, and how the 2025 refrigerant rules affect a like-for-like swap.
• You have inherited plant and are not sure what you owe. Start with TM44 intervals and F-gas checks, which sets out the two thresholds that decide everything, then maintenance.
• You are the landlord, not the occupier. Commercial landlord obligations covers how these duties are usually allocated, and why the lease rather than the deeds decides.

Two numbers decide your duties

Before sector, before system type, two figures determine which legal obligations apply. Your commissioning paperwork or the unit nameplates carry both.

12 kW effective rated output. Above this, the system falls within the statutory air conditioning inspection regime and must be inspected by an accredited energy assessor at intervals not exceeding five years [1]. This is the combined output of all units serving a building under one person's control — four 4 kW cassettes in a retail unit clear the threshold together even though none does alone.

5 tonnes CO₂ equivalent of refrigerant. Above this, F-gas leak-check duties bite: annual checks in the 5–50 tCO₂e band, six-monthly from 50 tCO₂e, quarterly above 500 tCO₂e, with intervals doubled where certified automatic leak detection is fitted [3][4].

The two are independent, which is what catches people out. A 9 kW split serving a server room escapes the inspection regime entirely and still carries enough refrigerant to trigger annual leak checks. Neither duty is a maintenance schedule: an assessor will not clean your filters, and a leak check confirms refrigerant is not escaping, not that the plant is running well.

Choosing a system

Commercial selection turns on zone count and how independently those zones must run.

• Split and multi-split — a handful of zones, straightforward plant, the lowest capital cost. The right answer for most small offices, shops and treatment rooms.
• VRF — many zones on one refrigerant loop, with heat-recovery designs able to heat one zone while cooling another. The default above roughly six to eight zones, and the reason a north-facing meeting room and a south-facing floor can both be comfortable at once.
• Ceiling cassettes — the usual indoor format where there is a suspended ceiling, giving four-way throw without wall clutter.

Capacity should follow a proper heat gain calculation — occupancy, equipment load, glazing and orientation, per CIBSE Guide A methodology [6] — not a rule of thumb per square metre. Offices are dominated by people and IT load, kitchens by cooking equipment, server rooms by a continuous sensible load that never varies with the weather. Those are different design problems, and a specification that ignores the difference will disappoint in the room that matters most.

Air conditioning by sector

Every space has demands that change the specification, not just the size.

Offices · retail · restaurants and hospitality · clinics and dental practices · gyms and fitness studios · server rooms · schools and classrooms · care homes · hotels · warehouses

On the duty to occupants: there is no legal maximum workplace temperature in the UK, but employers must keep temperature reasonable and assess the risk where work is thermally demanding [5]. That framing matters when cooling is being justified internally — it is a risk assessment question, not only a comfort one.

What it costs

Commercial pricing depends on floor area, zone count, occupancy pattern and system type. The commercial cost guide sets out the variables; for per-unit budgeting there is split system installation cost, and for reversible systems, commercial air-to-air heat pump costs.

What moves a quote is rarely the equipment schedule. It is plant access — whether a condenser reaches the roof by stair, hoist or crane — the ceiling type and how much of it must come down, whether the work must happen outside trading hours, and whether the electrical supply needs upgrading before anything else can proceed. Two identical schedules in two buildings can differ by a factor of two on those grounds alone, which is why a firm number comes from a survey rather than a form.

Efficiency and the recurring calendar

Running cost is the larger lifetime figure, and it is mostly decided at design. Commercial energy efficiency covers where it goes — zoning, controls and setpoint discipline usually beat equipment selection — and maintenance covers what a service visit should measure and how to read a contract before signing it.

Planning and compliance covers the permissions, F-gas duties and inspection regime that apply to business premises, including the point most guides miss: under-maintaining a system can shorten your statutory inspection interval rather than saving you work.

Get a business quote

Tell us about the premises and the project and we will review the enquiry individually. Start a business enquiry — one enquiry goes to one installer, and your contact details stay private until that installer accepts the job.