The Heat Tax Hiding in Plain Sight

By Jay Pzier
Principal Engineer - Codes and Standards | CEM, HBDP

It’s hot outside; it’s even hotter inside as temperatures climb all morning inside the manufacturing plant. It’s only a matter of time before employees working on the shop floor start to wilt as the heat drains their focus and energy.

This is how heat takes a toll on employees, often before anyone recognizes it as a safety issue. There is no general-ledger account called “excessive heat,” but it’s a price many organizations pay nonetheless. Before the effects of heat show up in a spreadsheet, they manifest themselves in human behavior. By the last half of the workday, employees may not be working optimally. Some go home exhausted. Others leave at the first opportunity for a job in a better environment. That is the heat tax. It shows up in lost working time and in the cost of keeping people in a difficult environment. It is impossible to attach a universal dollar figure to the loss of heat-related productivity. Workplaces differ, as do people. But that doesn’t mean the cost is imaginary, even if the cost is easy to ignore.

Employees are only trying to protect themselves. But if someone is seeking relief from the heat, that person is obviously not working.

Many companies have learned to live with hot working conditions. In fact, “That’s just the way it’s been” is a surprisingly durable capital-planning philosophy. Employees have always found a way to get through the shift. Over time, that history can make excessive heat seem like an unavoidable part of the job.

We need to update that perspective because employers have an enlightened self-interest in the health and well-being of their employees. When an employee reports they were so exhausted when they got home that they just collapsed from fatigue, the last half of their workday was probably not very productive. As an employer, I want my employees to enjoy their evenings and then return ready to work the next day.

WHEN HEAT STARTS TAKING TIME

The heat tax may be difficult to calculate as one figure, but parts of it can be measured. Heat does not have to send someone to the hospital before it begins costing a business time. The National Institute for Occupational Safety and Health recommends limiting time in the heat and allowing workers to recover in a cool area. Its sample schedule for heavy work at 95 degrees Fahrenheit calls for 15 minutes of rest each hour. At 100 degrees, work and recovery split the hour evenly. The actual schedule depends on humidity, direct sun and the work being performed.

A 2025 field study led by Leonidas Ioannou examined 603 shifts across several countries and industries. After matching more than 16 million seconds of video with conditions during each shift, the researchers found that work-time loss was lowest around 64 degrees Fahrenheit and rose as temperatures moved in either direction.

Heat may also affect judgment. For instance, a forklift operator laboring in extreme heat who is miserably uncomfortable may make a poor decision.

Every respondent to the exit survey said having fans at work was important. Seventy-nine percent felt more effective when the fans were running. Sixty percent said they felt much more effective, while 19% felt a little more effective. At comparable temperatures, workers were also less likely to say the heat made it difficult to work effectively when the fans were running.

That is evidence of perceived effectiveness, not measured productivity. The study took place at NovelAire, which makes complex custom equipment. The researchers could not compare the number of units made with the fans on against the number made with them off.

The Berkeley researchers also found physiological evidence consistent with the benefits of air movement. With the fans running, workers’ average sweat rate was about 29 grams per hour lower during May and June and about 38 grams per hour lower during August mornings. The researchers said that at those temperatures, the fans increased convective cooling, which reduced the amount of sweat needed to cool the body. During the hotter August afternoons, workers produced about the same amount of sweat with or without the fans, but the researchers concluded that the added air movement probably helped more of that sweat evaporate and carry heat away from the body. Fan use did not worsen the heart-rate or sublingual-temperature measures tracked during the study.

Studying people in an operating factory gets complicated. Employees performed different jobs at different levels of physical effort. Their clothing and activity were not controlled. The workers’ comments help explain what the survey results meant during an ordinary day. They described the fan-off days as tiring and said they left work drained and dehydrated. One worker reported that without the fans, all he wanted to do was go home and crawl into bed. When the fans were running, he could have a normal evening.

COOLING PEOPLE IS NOT A PLACEBO

For years, the fan industry leaned on the phrase “perceived cooling effect.” We had a large customer interpret the phrase to mean that fan-based cooling was a placebo. The customer mistakenly concluded that fans didn’t actually cool people and could therefore become dangerous above 85 degrees.

The way a ceiling fan works is that air movement across your body increases heat transfer through the temperature difference and through the evaporation of moisture off your skin. Per physics, under most conditions, air moving across your skin is actually removing heat from your body. Anyone who has ever stood in a breeze at the beach understands it.

“Sweat on the floor does you no good because cooling the floor does not make you any cooler.”

Sweat makes the mechanism visible. In hot, stagnant conditions, the body may sweat faster than the moisture can evaporate. Clothes become soaked and sweat rolls off the skin, landing on the floor. With suitable air movement, however, more of that moisture can evaporate from the skin and do the job the body produced it to do.

AIR CONDITIONING THE BUILDING, NOT THE BLOCK

Conventional air conditioning can be impractical or painfully expensive in an industrial facility. High ceilings create an enormous volume of air. Loading docks open and close all day. Heat comes off the roof and the equipment below it. Trying to hold a warehouse at an office temperature can amount to air conditioning the block, not the building.

THE “SPINNY THING” PROBLEM

Once a company accepts that air movement can help, another question follows: Why not buy the cheapest large fan available?

It’s a fair question. A cheap fan will produce a breeze. People see a ceiling fan and think of the spinny thing in their bedroom. In an industrial building, it also has to coexist with sprinklers and lights, and it may have to clear racks or cranes. Now consider a 300-pound object with blades spinning at 40 miles per hour at the tips over people running forklifts.

We have applications engineers who help customers apply the product correctly. For a large building, an engineer can walk the space and lay out the products, then run everything through a simulation and model all the airflows. Using Big Ass Fans’ proprietary SpecLab® CFD software, engineers build a customized 3D digital model of the facility that factors in building layout, structural obstructions, and thermal conditions to predict exact airflow patterns. One example compared an original 15-fan layout with a customized layout that focused 12 fans over the dock areas and product aisles. The original layout averaged 87 feet per minute in the dock area. The customized layout averaged 258 feet per minute. When I started, you would walk in, say “about right here” and hope. Now we can demonstrate visually and quantitatively how the fans will work before the customer installs anything.

Safety engineering matters just as much as airflow performance. When operating equipment over people and operations, safety cannot be an afterthought. It requires a complete, multi-layered approach to deliver industry-leading safety standards. Flagship models like the Powerfoil X4 feature eight redundant safety systems, such as double safety cables, patented airfoil retainers, and integrated fire relays, to ensure every component stays secure under all conditions. That same level of discipline extends to custom mounting, precise clearance standards, and smart controls. Lower purchase prices are no bargain if the equipment introduces liability or needs constant service visits that disrupt daily business.

I usually get involved when we’re solving a problem the customer can’t solve or can’t solve economically. Sometimes my job is to tell the customer we’re not the answer and point them to another product. That builds trust.

The same caution applies to any claims we make. That is why I point customers to research from Cal Berkeley, the University of Sydney and Lawrence Berkeley. When we publish our own work, we place it in peer-reviewed journals where competent people can review it critically and make sure what we’re saying is real. Properly applied fans produced a large improvement in how workers experienced the heat and how hard the work felt. The physiological measures tracked by the researchers didn’t get worse.

Every hot facility won’t need the same equipment. But “we have always worked this way” isn’t an engineering analysis. Excessive heat is an operating condition that affects people, and people affect the operation. And it’s only getting more acute. According to NOAA’s National Centers for Environmental Information, 2024 marked the warmest year for the contiguous United States since national recordkeeping began in 1895. An Environmental Protection Agency analysis of NOAA records found that average temperatures across the country have increased by 0.32°F to 0.55°F per decade since the late 1970s.

“the heat tax has been there all along, hiding in plain sight.”