A guide for business owners and facilities managers: how packaged, split, VRF and chilled water systems compare, how cooling loads are worked out, and where commercial systems save or waste energy.
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Air conditioning in a business gets judged differently from air conditioning at home. It runs longer hours and serves more people. It has to deal with heat from computers, lighting and equipment, and it comes with legal duties most domestic systems never get near. It's usually one of the bigger energy users in the building too, so decisions made at design stage show up on the electricity bill for years.
We've written this guide for owners, office managers and facilities teams who are thinking about a new system or an upgrade, or just want to run their existing one better. It compares the main technologies and explains how cooling loads are worked out. It also points out where energy most often gets saved or lost.
Commercial air conditioning is any system that heats or cools a workplace, shop, hospitality venue, public building or technical space such as a server room. The equipment can be anything from a single wall-mounted split in a small office to large multi-zone systems covering whole floors. The hardware isn't really what makes it different. It's the demands on it. Operating hours are long and occupancy changes, different zones want different things, and the operator has responsibilities under the F-Gas regulations and energy rules.
Most commercial buildings in the UK use one of four broad technologies, and each tends to suit a particular kind of building.
| Technology | How it works | Typical fit |
|---|---|---|
| Split and multi-split | Indoor units connected by refrigerant pipework to one outdoor unit | Small offices, shops, surgeries, individual rooms |
| Packaged units | All refrigeration components in a single cabinet, often roof-mounted, supplying air through ductwork | Single-storey retail, warehouses and buildings with roof space and existing ducts |
| VRF / VRV | One or more outdoor units vary refrigerant flow to many indoor units, each zone controlled separately | Multi-room offices, hotels, schools and mixed-use buildings |
| Chilled water | A chiller cools water, which is pumped to fan coil units or air handlers around the building | Large buildings and campuses with a central plant room |
What you actually see inside the building is usually a ceiling cassette or a ducted unit hidden above a suspended ceiling. Where there's no ceiling void, wall-mounted and floor-standing units are used. Indoor air handlers come in where conditioned air has to be distributed through ductwork.
In a lot of buildings, some rooms need cooling at the same moment others need heating. Think of a sunny south-facing meeting room next to a cooler north-facing office. Heat recovery VRF can move heat out of the zones being cooled and into those being heated, cutting the total energy needed. It suits buildings with mixed orientations and uses, so if that pattern looks likely, raise it at design stage.
Commercial cooling is sized on heat gains. Floor area on its own tells you very little. A meeting room for twelve people needs far more cooling than an archive room the same size. A proper load assessment adds up:
Next the designer splits the building into zones with similar needs, allowing for the fact that they won't all peak at once, and thinks about how the space might change. Open-plan offices often get partitioned later on, and a system designed with flexible indoor unit positions copes much better with a refit. Undersize it and you'll get complaints on the hottest days. Oversize it and you've wasted capital on a system that runs inefficiently the rest of the year.
Under the Workplace (Health, Safety and Welfare) Regulations 1992, employers have a duty to keep indoor workplace temperatures reasonable. Past the legal minimum, temperature directly affects concentration, comfort and the number of complaints you get. A low number on the thermostat isn't the goal. Even conditions are. That means no cold draughts over desks and no hot spots by the windows, with humidity kept in a comfortable range.
Air conditioning recirculates and conditions the air in a room. On its own it brings in no fresh air. Most workplaces also need mechanical or natural ventilation to meet fresh air requirements, and the two systems should be designed together. Our page on ventilation with air conditioning explains how they combine.
Commercial equipment is compared on seasonal efficiency figures. SEER (seasonal energy efficiency ratio) shows cooling efficiency over a typical season, and SCOP (seasonal coefficient of performance) does the same for heating. The higher the number, the more cooling or heating you get for each unit of electricity.
Seasonal figures matter more than peak ratings, because a commercial system spends most of its running hours well below full output. Inverter-driven compressors slow down instead of switching on and off, and they do best in exactly those part-load conditions. When you compare quotations, including any from UK Aircon, put the seasonal efficiency next to the equipment price. The cheaper unit isn't always the cheaper system to own.
To estimate running costs for any unit, multiply its electrical input in kW by the hours it runs and your unit price in p/kWh. Our post on air conditioning running costs works through the calculation.
On plenty of commercial sites the biggest efficiency gains come from the controls, without buying any new equipment. Common improvements include:
Energy assessments on existing systems are one of our specialist air conditioning services. We look at how the equipment is set up and controlled, and where consumption could come down. Businesses in West Yorkshire can find local details on our Leeds air conditioning page.
Whoever operates a commercial system has specific responsibilities. That's usually the building owner or the tenant who controls it. The main ones are:
With a planned maintenance programme, servicing happens on a schedule instead of only when something goes wrong. For a business, a good programme usually starts with an asset list of every indoor and outdoor unit. Service visits are set at intervals that match how hard each system works, and high-dust areas get their own filter cleaning schedule. Statutory leak checks are included where they apply, and every visit is written up. Office systems are commonly serviced every six months. Restaurants, gyms and server rooms often need a visit every quarter.
You get fewer breakdowns at busy times and steadier running costs, along with a clear paper trail for compliance and warranty claims. Our article on air conditioning maintenance explains what each service visit should cover, and UK Aircon offers maintenance agreements for commercial clients.
The older a system gets, the harder it is to justify keeping. Watch for repairs becoming more frequent, parts going out of production, R22 refrigerant, poor control over individual zones and energy use well above modern equipment. Any of those is a sign to plan a replacement before the system fails on its own. A planned replacement can be phased floor by floor or zone by zone, and the survey will show whether any existing pipework, cabling or containment can be reused.
A quotation is only as good as the information behind it. Before you ask contractors to price a project, pull together the following so every quote rests on the same assumptions:
The survey will confirm all this and fill in the gaps. Even so, a clear brief speeds things up and makes it much easier to compare like with like.
Both connect several indoor units to outdoor equipment. VRF systems vary refrigerant flow to each zone, can serve many more indoor units over longer pipe runs, and are available with heat recovery. Multi-splits suit smaller premises with a handful of rooms.
No. Standard air conditioning recirculates and conditions room air. Fresh air must come from mechanical or natural ventilation, which should be designed alongside the air conditioning so the two work together.
Compare seasonal figures: SEER for cooling and SCOP for heating. They reflect performance across a typical year, including the part-load conditions where commercial systems spend most of their time, rather than a single peak rating.
The operator, usually whoever has practical control of the system, such as the owner or tenant, is responsible for arranging leak checks on systems at or above 5 tonnes CO2-equivalent and keeping records. The work must be done by F-Gas qualified engineers.
Yes. Most modern split, multi-split and VRF systems are heat pumps and provide efficient heating as well as cooling. Heat recovery VRF can heat some zones while cooling others at the same time.
From a single office to a multi-zone building, UK Aircon designs, installs and maintains commercial systems with REFCOM-registered engineers. Visit our commercial air conditioning installation page or contact us for a free quote. We reply within 24 hours.
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