Air conditioning for shops, offices and warehouses: what actually changes

The same kW, four different problems

Two commercial buildings with identical floor areas and identical installed cooling capacity can behave completely differently, because what a building is for determines where its heat comes from, when it arrives, and what can physically be done about it.

This guide compares the four building types we are asked about most. The detail for each sits on our sectors pages; what follows is the comparison.

Offices: the simultaneity problem

An office faces several directions at once. On a bright spring morning the south and east elevations take substantial solar gain while the north side takes none — so rooms a few metres apart need opposite things from the system at the same moment.

That is why zoning should follow aspect rather than the floor plan, and why heat-recovery VRF suits offices so well: it can cool the sunny side while heating the shaded side, moving the heat between them instead of rejecting it outside. The classic complaint that "one side is freezing and the other is boiling" is nearly always a zoning fault rather than a plant fault.

Two office zones need separate treatment. Meeting rooms carry a high transient load and benefit from occupancy or CO₂-based control. Comms rooms run continuously all year and should never sit on the general office system, which will be scheduled off overnight and at weekends exactly when the comms room still needs cooling. See office air conditioning.

Retail: the building is open on purpose

Retail breaks the assumption underneath most cooling calculations — that the building is broadly sealed. A shopfront held open through trading hours admits outside air continuously, and on a hot day that infiltration load can exceed all the internal gains combined.

It cannot be engineered away, only designed for, usually with an air curtain sized for the full opening height. Three things determine whether that works: correct sizing, proper commissioning of jet angle and velocity, and — genuinely the most common failure — whether staff leave it switched on.

The second retail load is display lighting, chosen to make products look good rather than to be efficient, and concentrated over feature areas and window displays rather than spread evenly. Converting older halogen display lighting to LED removes a meaningful share of the cooling load, so if both a relighting scheme and a cooling replacement are planned, sequence them so the cooling is not sized against a load about to disappear. See retail air conditioning.

Warehouses: usually the wrong question

A large distribution unit encloses an enormous volume with a big, often lightly insulated roof and very few people. Cooling all of it to office conditions is rarely affordable and rarely necessary — so the productive response to "how much to air condition our warehouse?" is normally to narrow the brief.

The sequence that works: attack roof gain through insulation or reflective treatment; ventilate so accumulated heat can be flushed when outside air is cooler, which in the UK is most of the year; add air movement at the occupied zone, where large-diameter low-speed fans give a real cooling sensation without changing air temperature at all; and only then add refrigeration, targeted at the packing benches, the internal offices, or a temperature-controlled enclosure for stock with a stated specification.

Worth noting that in most UK warehouses heating is the larger annual cost, so if plant is being replaced anyway the heating question deserves at least equal attention. See warehouse and industrial cooling.

Restaurants and kitchens: extract governs everything

Hospitality is the most technically involved of the four, because the kitchen extract dominates the whole building. A large extract rate must be balanced by an equivalent supply of tempered make-up air; when it is not, the building runs at negative pressure and the symptoms are unmistakable — heavy front doors, whistling gaps, cold draughts through the dining room, and extract hoods that stop capturing properly because there is not enough air for them to move.

Grease adds two more problems: a combustible deposit inside ductwork, which makes kitchen extract cleaning a fire-risk control governed by TR19 Grease rather than a housekeeping task; and fouling of any condenser sited near the extract discharge, which is a common and easily missed cause of a cooling system that "used to cope".

Late-night operation next to residential neighbours makes noise a leading source of complaint, and a BS 4142 assessment here must use the night-time background rather than the daytime figure. See restaurant and kitchen ventilation.

What does not change

Whatever the building, the fundamentals are constant. The load must be calculated per zone, never assumed from floor area — see our sizing guide. The system must be commissioned with measured records. The controls must match real occupancy. And the same two legal duties attach to the air conditioning regardless of what the building does: F-Gas leak checking and record-keeping, and a TM44 inspection where effective rated output exceeds 12 kW — a threshold that aggregates across the whole building.

Frequently asked questions

Does building type really change which air conditioning I need?

Substantially. Offices commonly suit heat-recovery VRF because different aspects need heating and cooling simultaneously; retail is dominated by infiltration through an open shopfront; warehouses usually call for targeted spot cooling rather than whole-volume conditioning; and hospitality is governed by the balance between kitchen extract and make-up air.

Why does our shop struggle in summer when the office next door is fine?

Most likely the open shopfront. A door held open through trading hours admits outside air continuously, and that infiltration load can exceed all the internal heat gains combined on a hot day — a load a sealed office simply does not have. An air curtain, correctly sized and left switched on, substantially reduces it.

Is it worth cooling a whole warehouse?

Usually not. The volume is enormous, roof gain is significant and occupancy is low, so conditioning the entire space is expensive to install and to run for the benefit of few people. Addressing roof gain, ventilation and air movement first, then targeting cooling at occupied zones, offices or temperature-sensitive stock, delivers most of the benefit for far less.

Do the same regulations apply to every building type?

The core ones do. F-Gas leak checking and record-keeping apply to any refrigerant-bearing plant, and the TM44 inspection duty applies wherever a building's air conditioning exceeds 12 kW effective rated output, aggregating across all units. Some sectors add requirements of their own, such as TR19 Grease for kitchen extract ductwork.

Compare all four on the sectors index, or see commercial air conditioning for system selection and cost guides for indicative pricing.