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- Indoor heat rules
It is 90°F on the floor. What actually happens next?
Five kinds of space that get hot, crossed with the four reasons people call us about it. One instruction per space, an honest account of what the building will allow, and a clear line around the parts of this that are not a heating and cooling contractor’s to solve.
Three things that apply to every answer below
- We measure. We do not certify.
California’s indoor heat illness prevention standard, section 3396 of title 8, has applied to most indoor workplaces since July 2024. In outline it begins at 82°F, requires cool-down areas kept below 82°F, and brings in further control measures at 87°F — or at 82°F where clothing restricts heat removal or there is high radiant heat. Those figures are quoted from the standard, not interpreted. Read the text or ask a safety consultant. What we can give you is dated, located temperature readings and the equipment to change them. Whether any of it satisfies an obligation is not ours to say, and we will not say it.
- One reading settles nothing. A week of readings settles most things.
The temperature at the moment a contractor is standing in your building is the least useful number available. Loggers left at working height for a week, reported as a graph of the working day, turn a disagreement into a record — and they frequently show the problem is two hours long and in one part of the floor, which is a much cheaper problem than the one everybody assumed.
- The cheapest fix is often not equipment.
Moving air, extracting heat at its source, shifting a schedule, shading or coating a roof, and splitting a zone are all routinely more effective per dollar than adding cooling capacity. We will price cooling if cooling is the answer. We would rather show you the measurement that says it is not.
Work out what happens next
Pick the space and pick why you are asking. Every answer below is on this page whether you pick anything or not — the picker only narrows it down.
Section 3396 governs employers and the people they employ. In your own home it is simply not in play, and neither is any obligation, any plan or any record-keeping. Everything below about logging, documentation and cool-down areas can be ignored. If anybody knocks on a residential door citing heat regulations, they are selling. We will not use a regulation to sell you anything in your own home, and the rest of this page is written for buildings where somebody goes to work.
Log the temperature at working height for a week before anybody prices cooling.
In a tall building the warm air is at the roof and your people are on the floor, and the two can differ by a great deal. The number that matters is the one at head height at the pick faces, at three in the afternoon, in August — and that number is the only sound basis for deciding what, if anything, to install.
What a storage or distribution building allows
Cooling the whole volume of a tall building is possible and it is almost always the wrong answer, because you are paying to cool a large quantity of air that nobody is standing in. The interventions that actually move the number at floor level are, roughly in order of cost:
- Destratification or high-volume low-speed fans. Air movement over people is worth several degrees of perceived temperature on its own, and pulling the roof air down evens out the building.
- Ventilation that actually changes the air — powered extraction at the ridge with make-up air at low level, rather than open doors and hope.
- Roof treatment. A reflective coating or added insulation on a large flat roof changes the heat coming in, which is upstream of everything else.
- Spot or zone cooling at the pick faces, packing benches and offices — cool the people, not the racking.
- Full building cooling, which is real, and occasionally right, and worth pricing last rather than first.
Dock doors deserve their own note: a building with doors standing open all day cannot hold a temperature, and the honest options are curtains and scheduling rather than more plant.
Find the heat source and measure it separately. Cooling a room that a machine is heating means paying twice.
On a production floor the heat is usually being made inside the building — by ovens, compressors, motors, presses or process equipment. Extraction at the source is cheaper and more effective than cooling the room it escapes into, every time, and it has to be established before capacity is discussed.
What a production floor or workshop allows
Three measurements decide this, and they are different measurements from the ones a comfort job needs:
- Air temperature across the floor, logged, at working height.
- Radiant heat near anything hot. A person standing beside a furnace or a press is being heated by radiation, and the air temperature does not describe that at all. It needs measuring as its own quantity.
- Humidity, which decides whether sweating works and therefore decides how the same air temperature feels.
The usual answers are local extraction, canopy hoods over the process, insulation or screening of hot surfaces, and directed air movement at the work positions. Whole-room cooling comes last and sometimes not at all. Where the extraction is dealing with fumes, dust or a hazardous substance rather than heat, that is an industrial hygiene job and we will tell you to get one.
Measure the make-up air against the hood exhaust before anything else.
Nearly every hot kitchen we are called to is out of balance: the hoods are pulling more air out than anything is putting back in. The kitchen then draws its replacement air from the dining room and the street, the line gets hotter, the front of house gets harder to control, and no amount of cooling fixes it because the cooling is being pulled out through the hood.
What a commercial kitchen allows
Once the balance is measured, the realistic moves are dedicated make-up air, tempered so it is not blowing hot outside air at the line in August; extraction sized to the equipment actually installed rather than to the equipment that was there when the hood went in; and targeted air movement or spot cooling at the fixed work positions, which in a kitchen are always the same three or four places.
Kitchens are also where the humidity and the radiant heat matter most, and where the equipment schedule matters — a fryer bank and a combi oven running together is a different load from the same kitchen at ten in the morning.
We do not clean hoods, we do not certify fire suppression, and we do not sign off grease duct work. Those are separate licensed trades. We work on the air and we will tell you who to call for the rest.
Measure each zone at the hour the complaints happen. This is nearly always zoning wearing a capacity problem’s clothes.
A floor with one thermostat, a glass elevation at one end and an interior corridor at the other will never be comfortable at both ends, whatever equipment is fitted. The complaints almost always cluster at one time of day and in one part of the floor, and the measurement has to be taken then and there rather than at nine in the morning.
What an office or retail floor allows
The usual findings are a thermostat in the wrong place — in the corridor, under a light, or on the sunny wall; a floor plan that has changed since the ducts were run, with partitions now sitting across supply routes; and a schedule set for hours the building no longer keeps.
The answers are usually rebalancing, additional sensors, splitting the zone, and solar control on the glass, in that order of cost. On retail specifically: a door standing open all day is a trading decision, and the honest options are an air curtain, a schedule change, or accepting a figure on the bill. We will put numbers against all three rather than argue with the decision.
Decide what the door is doing before anything else.
A vehicle bay with the door open is not a space that can be cooled, and no equipment changes that. Everything sensible in a bay is therefore about air movement over the work positions, extraction of exhaust and process heat, and keeping whatever is above or beside the bay on its own zone.
What a vehicle bay or garage allows
Directed air movement at the lifts and benches does more here than anything else, because a bay is a large space with people in a small number of fixed positions. Exhaust extraction is a safety matter in its own right and should not be conflated with heat. Radiant heating in winter is usually the right call rather than warm air, since warm air leaves with the door.
The office or parts counter attached to the bay is the part that can genuinely be conditioned, and the most common fault we find is that it shares a thermostat with the bay, which is a hopeless arrangement for both. Separating them is frequently the whole job.
If the reason is an obligation to the people working there
Then the readings stop being diagnostics and start being records, and that changes how we take them: located, dated, at working height, at the hours people are actually there, and kept. We will give you the log, the instrument used and the conditions, in a form somebody else can check.
What we will not do is tell you whether it is enough. We do not certify compliance, we do not write heat illness prevention plans, and we do not train staff. Those are employer obligations and a safety professional’s work. A contractor who offers to handle all of it is offering something they are not qualified to give, and if it is ever tested that will matter.
The order we would suggest: get the record first, get advice on what the record means second, and buy equipment third. It is a slower route and it is the one that stops people spending money on the wrong part of the building.
If the reason is protecting stock or equipment
Then the target is not a comfort figure at all, and it does not come from us. It comes from the manufacturer’s specification, the supplier, the product’s own storage requirements or your insurer, and it is frequently a humidity limit rather than a temperature one. Get that number in writing before anything is designed around it.
Two things follow. First, the measurement has to be taken where the goods or the equipment sit, which is often high on a rack or inside a cabinet and not where anybody walks. Second, stability usually matters more than the absolute figure — a store that cycles between two extremes twice a day is harder on stock than one that sits steadily at the upper end.
Server rooms, cold rooms and refrigerated storage are their own disciplines. We will say plainly when a job has crossed into one.
If the reason is plain comfort
That is a completely legitimate reason and it deserves the same measurements, with one difference: the cheapest thing that works, wins, and you are free to decide what is worth it.
Air movement is the most under-used option in this category. Moving air over a person is worth several degrees of perceived temperature and costs a fraction of what cooling the same space costs. Humidity is the second: the same air temperature is markedly more comfortable drier. And glass is the third — on a west elevation, solar control does more than the equipment that is being asked to fight it.
We will always price cooling if you want it priced. We will also tell you when a fan, a blind and a schedule change would have got you most of the way for a tenth of the money.
If it is your own home
Then none of the workplace material above is relevant to you, and the questions are the ordinary ones: is the system the right size, do the ducts leak, is the air getting to the room, and is the equipment working as it should. All of those are measurable and all of them are on our homes page.
The one thing worth carrying over from the commercial side is the logging. A cheap sensor left in the hot room for a week, recording overnight and through the afternoon, tells you far more than any single reading — and it is the difference between a diagnosis and an argument.
Where this page stops
We will measure anything described here and give you every figure with its date, its location and the conditions it was taken in. We will tell you what it means mechanically, and where we are not sure we will say so rather than guess.
We will not certify compliance with the indoor heat standard or anything else, write your plan, train your people, make a health claim from a reading, or quote a price for a building we have not seen. If the readings show a carbon monoxide problem, that is the one item on this page that is urgent and it gets dealt with straight away. Everything else can wait for a week of data.