Why a Commercial Kitchen Gets Too Hot

Is there a legal maximum temperature for a kitchen?

No. Regulation 7 of the Workplace (Health, Safety and Welfare) Regulations 1992 requires that the temperature in all workplaces inside buildings shall be reasonable during working hours, and that is the whole of the duty. The Health and Safety Executive is direct about why no upper figure exists: every workplace is different, and in places such as bakeries and foundries the high temperature comes from the work itself rather than the weather. A commercial kitchen is squarely in that category.

What follows from that is more demanding than a number, not less. With no threshold to point at, an employer has to be able to show they assessed the risk and did something about it. Under the Management of Health and Safety at Work Regulations 1999 that assessment is a legal duty in its own right, and heat in a kitchen is one of the more obvious things it should cover.

A staff complaint about heat is not a complaint about comfort. Working through a service at temperature costs concentration first, which is why kitchen heat shows up as burns, cuts and mistakes on the accident book before it shows up anywhere else.

Why is the kitchen so hot?

Six causes cover almost all of it, and the first three are extraction faults that a kitchen has usually stopped noticing because they arrived gradually.

Extraction removes heat only if it captures it

This is the distinction that decides whether the money spent on a hot kitchen does anything. An extract system takes away the column of hot, greasy air rising off the appliances. It does that at the canopy, and only for the heat that reaches the canopy.

Heat that escapes the capture area is in the room, and the extract fan cannot get it back. So a kitchen with a healthy fan and an undersized canopy is hot for the same reason a kitchen with a stopped fan is hot, and the two need completely different work. Measuring is how they get told apart.

The other half is the supply. Every cubic metre the canopy removes has to be replaced, and a kitchen without designed make-up air simply cannot achieve the extract volume it was specified for, however healthy the fan is. Why make-up air decides the extract volume.

How do I reduce heat in a commercial kitchen?

In this order. Each step is cheaper than the one after it, and each one changes the answer to the next.

1. Measure the extract against its design figure. Until that number exists, everything else is a guess. It is also the step that most often ends the exercise.
2. Clean the filters and the duct run. Grease narrows the route and costs volume everywhere.
3. Sort the make-up air. A kitchen that cannot breathe in cannot breathe out.
4. Check the canopy against the appliance line. Size, height and overhang past the equipment underneath it.
5. Deal with the heat that never reaches the canopy. Dishwashers, hot holding and uninsulated pipework.
6. Then consider cooling. Only once the five steps above are done, because cooling a room that is losing its extraction is the expensive way to treat a symptom.

What we do, and what we do not

We work on the extraction: the canopy, the ductwork, the fan, the filtration and the make-up air that replaces what leaves. On a kitchen running hot, that covers the first five steps above and, on most sites, it is where the problem was.

Air conditioning and spot cooling are a separate trade and we do not supply them. If a survey finds the extraction performing to its design figures and the room still overheating, the honest answer is that extraction is not the remaining problem, and we will say so rather than sell a fan. How we measure an existing system, and canopy installation where the capture area is the fault.