Industrial air conditioning for factories and plant

What does a factory or plant site actually need to cool?

On an industrial site the useful question is not how big the building is but what must stay cool, and why. Five jobs recur.

Area	Why it is cooled	Usual approach	Settle early
Control room and offices	People work there all shift and screens add heat	Split or VRF sized like any room, with filtered air to keep dust out	How hot the surrounding hall is, which changes the load
Panel and electrical rooms	Drives and controllers have an ambient limit set by their maker	Ducted or packaged units with duty and standby	The heat the equipment gives off, in kW, and the maker's limit
Clean production areas	The process specifies temperature, humidity or particle count	Air handling unit with filtration and pressure control	The specification from the process owner
Hot processes	Ovens, furnaces and presses load the hall with radiant heat	Capture at source, shielding, spot cooling, air movement	Radiant heat, which room cooling does little about
Hostile atmospheres	Dust, oil mist, solvent vapour, corrosive or flammable air	Sealed or filtered equipment, remote condensers, extraction at source	Which substances are present and whether any zone is classified

Warehouse-style sheds have their own page on warehouse air conditioning, and server and comms rooms on site follow the server room cooling requirements.

Which cooling systems are used on industrial sites?

• Packaged units put every component in one cabinet, so there is no refrigerant pipework across the hall. They suit a roof or a yard beside a room.
• Ducted and multi-split systems serve rooms from outdoor units placed away from dust, fumes and forklift traffic.
• Chilled water from a chiller feeds air handling units, fan coils or machinery loops, and suits many points or a large load. The commercial chillers page covers specification; glycol loops for machinery are in the guide to process and glycol chillers.
• Evaporative and adiabatic cooling cools by evaporating water, compared in the guide to evaporative cooling and air conditioning. HSE lists cooling towers and evaporative condensers among the most common legionella sources, so water-using designs need a risk assessment.
• Spot cooling and air movement aim cool air or a breeze at the people or equipment that need it, as with large slow fans.

Retained Regulation (EU) 2016/2281 sets ecodesign requirements for cooling products up to 2 MW but excludes "custom-made products assembled on site, made on a one-off basis", so ask a supplier which rules a product falls under.

When is cooling the whole factory the wrong answer?

HSE says "there's no law for maximum working temperature" because in many indoor workplaces heat is "created by work activity, for example in bakeries or foundries". It adds that "air temperature alone is not a valid or accurate indicator of a comfortable workplace temperature", and that radiant temperature "will have a greater influence than air temperature on how hot the workplace will feel". A hall full of radiant heat is not fixed by chilling its air.

HSE's control measures include separating the source of heat from workers, barriers that shield them, and increased air movement. A sensible order follows from that: contain heat at its source, shield people from radiant heat, move air over them, condition the rooms where people stay for hours, and cool the whole hall only if the process requires it. For example, in a hypothetical 3,000 square metre hall with two ovens, capturing the oven heat at a hood and conditioning a supervisors' booth is a smaller and different job from cooling the hall.

What changes when the air is dusty, oily or hazardous?

Dust and oil mist foul filters and coils, so intakes sit away from the source and filters and coils need cleaning access (see filter grades and air handling units). Room cooling and general ventilation dilute contaminants; they do not capture them. HSE's ventilation guidance says it "does not cover the removal of harmful substances from the air such as welding fumes and dust generated by processes", and points to COSHH and local exhaust ventilation (LEV).

• Oil mist. HSE's metalworking fluids guidance lists inhaling "the mist generated during machining/shaping operations" as a route of harm and names enclosures and local exhaust ventilation as controls to check and maintain.
• LEV testing. HSE says LEV needs "a periodic thorough examination and test (at least every 14 months)", with the record kept for at least 5 years.
• Explosive atmospheres. DSEAR requires employers to "identify and classify areas of the workplace where explosive atmospheres may occur and avoid ignition sources" in them, so equipment for a classified zone is chosen for it. See ATEX air conditioning.

Which duties apply to industrial air conditioning?

• Fresh air. HSE quotes regulation 6: employers must ensure every enclosed workplace is ventilated by "a sufficient quantity of fresh or purified air".
• Temperature. HSE gives no maximum, but says a minimum of "usually at least 16°C or 13°C for strenuous work" (thermal comfort), and warns that extreme process heat "can lead to serious health effects if not managed effectively" (HSE). The workplace temperature law guide goes further.
• F-gas leak checks. GOV.UK sets at least every 12 months for 5 to less than 50 tonnes of carbon dioxide equivalent, and every 6 months for 50 to less than 500.
• Energy inspection. The gov.uk guide applies it above 12 kW, but says it is not intended to cover systems that exist only to cool an industrial process.

How should a plant cooling brief be written?

1. State what must be kept cool (a room, a person, a product, a machine) and the temperature and tolerance it needs.
2. Get the heat load from equipment data: kW given off by panels, drives and machines, plus people and roof gain.
3. List what is in the air, including dust, oil mist, solvents and any classified zone.
4. Choose spot or room cooling, and say what happens in winter and at shutdown.
5. Plan access for filter and coil cleaning and for the LEV and leak checks.
6. Ask for commissioning records, as in the handover guide.

Where the answer is chilled water, the commercial chillers page explains how those systems are specified. You can send an enquiry through the form to ask for quotes against your own heat-load list.

Sources

• Temperature in the workplace: is it too hot or cold to work?, HSE, updated 26 May 2026, checked 22 October 2026
• Thermal comfort, HSE, checked 22 October 2026
• Ventilation in the workplace: overview, HSE, checked 22 October 2026
• Local exhaust ventilation (LEV): frequently asked questions, HSE, checked 22 October 2026
• About metalworking fluids, HSE, checked 22 October 2026
• The Dangerous Substances and Explosive Atmospheres Regulations 2002, HSE, updated 14 October 2024, checked 22 October 2026
• Legionella risks in your workplace, HSE, updated 30 September 2024, checked 22 October 2026
• Checking F gas equipment for leaks, Environment Agency and Defra, GOV.UK, checked 22 October 2026
• A guide to air conditioning inspections in buildings, MHCLG, GOV.UK, updated 18 September 2024, checked 22 October 2026
• Commission Regulation (EU) 2016/2281, Article 1 (as retained), legislation.gov.uk, checked 22 October 2026

Guides on this topic

• ATEX air conditioning for hazardous areas

Frequently asked questions

Is there a legal maximum temperature in a factory?

No. HSE says there is no law for maximum working temperature, because in many workplaces the heat comes from the work itself. Employers must still keep the temperature at a comfortable level and provide clean and fresh air, and HSE gives separate advice on heat stress in very hot processes.

Can ordinary split air conditioning go in a dusty or oily workshop?

It depends on what is in the air. Dust and oil mist foul filters and coils, so the contractor should say how the unit is protected and cleaned. Mist that people breathe is a COSHH matter to control at source with enclosures and LEV, and where an explosive atmosphere may occur the equipment must suit the classified zone.

Does an industrial air conditioning system need a five-yearly inspection?

If the air conditioning under one person's control has an effective rated output above 12 kW, the inspection duty applies in England and Wales. The gov.uk guide says it is not intended to cover systems that only cool an industrial process, so ask an energy assessor whether a given system is in scope.