Even before Adam and Eve picked and ate the fatal fruit of the tree of knowledge, condemning humanity to lives of sweat-soaked toil, they knew the meaning of good thermoregulation. Halfway through Milton’s “Paradise Lost,” God sends Raphael down to Eden for a chat with Adam. The archangel finds him in the doorway of his “cool bower,” taking shelter from the midday sun, which provides “more warmth than Adam needs.” (No adjusting the thermostat in Paradise.) Later, after God learns of the couple’s misdeed, he punishes them in part with inclement weather. He tilts Earth on its axis and gives the sun nefarious new instructions—“scorching heat” in summer, “pinching cold” in winter. Adam and Eve learn for the first time about ice, rain, hail, and snow. They must seek better clothing, Adam says, some new source of warmth, “to cherish / Our limbs benumbed.”
Milton never bothers to ask how Eve’s limbs felt, and the modern history of thermal comfort shows a similar tradition of neglect. It begins, quite literally, with a man in a business suit. In 1966, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) created Standard 55, a set of guidelines for indoor climate regulation. The standard, which has been updated periodically over the decades, relies in particular on a pair of numbers. The first number is known as the metabolic equivalent of task (MET) and expresses the energy cost of a given physical activity—operating a cash register, for instance. It was originally derived from studies of a forty-year-old, hundred-and-fifty-four-pound man. At rest, this Adam of metabolic equivalency expended 1.0 MET. The second essential number quantifies the thermal insulation of clothing according to something called the clo scale. A men’s business suit, plus the usual undergarments, footwear, and accessories, registers a 1.0 on that scale. In designing and operating a building’s climate systems, engineers and facilities managers are meant to consider how active workers will be and how they are likely to dress. An auto-repair shop, for example, where technicians wear coveralls and lug around exhaust manifolds (high clo, high MET), requires more cooling and ventilation than a surf shop, where clerks stand around in board shorts and flip-flops (low clo, low MET).
What if you’re not a forty-year-old, hundred-and-fifty-four-pound man in a business suit? What if you’re a woman? According to a study that appears Monday in the journal Nature Climate Change, you’re probably cold. For the study, Boris Kingma and Wouter van Marken Lichtenbelt, a pair of researchers at Maastricht University, in the Netherlands, asked sixteen young women to enter a climate chamber one by one. Each of the participants wore underwear, sport socks, a cotton T-shirt, and cotton-polyester sweatpants, for a grand total of about 0.58 on the clo scale. (They also wore fourteen coin-sized wireless skin-temperature sensors.) This outfit, Kingma told me, was not meant to simulate what a woman might wear to work, although a typical summer office getup—say, a lightweight blouse and pants—is even less insulating. The women sat behind a desk in a standard office chair (add another 0.10 clo of gluteal insulation) as the chamber fluctuated between warm and cool. They were asked to indicate at various points how comfortable they felt, from -3 (cold) to +3 (hot) on the ASHRAE scale.
Scientists who examine the interplay between humans and climate (they are known as biometeorologists) have sometimes found that women prefer the room a little warmer—about seventy-seven degrees Fahrenheit, according to a 1981 study from the journal Applied Ergonomics, versus about seventy-two for men. In 2012, Lisje Schellen, another Dutch thermo-obsessive, suggested that lower average skin temperatures along the arms and hands might explain women’s thermal dissatisfaction: chilly wrists make the whole body feel chilly. The results of Kingma and van Marken Lichtenbelt’s study indicate that, in addition to possibly preferring warmer temperatures to begin with, women produce less heat than the standard metabolic rate assumes—because, again, that rate was first developed with a man in mind. They conclude that, if building engineers were to adopt a new standard that took women into account, they could cut down on “gender-discriminating bias in thermal-comfort predictions.”
That the study appears in Nature Climate Change tells us something about its potential ramifications for the planet. Power plants spew out a third of this country’s carbon-dioxide pollution, which is why they are the targets of President Barack Obama’s Clean Power Plan, which was announced on Monday. But where does the electricity that they generate end up? According to the U.S. Department of Energy, about forty per cent of it goes to commercial and residential buildings, a number that has risen steadily since the nineteen-eighties. Heating, ventilation, and air-conditioning create the largest share of the demand. As our streets and parks have become increasingly warm, our homes and offices have become increasingly cool. Richard de Dear, a professor of building science at the University of Sydney, in Australia, refers to this phenomenon as “indoor climate change.” Unlike outdoor climate change, it doesn’t have a clear explanation. Perhaps the fact that people are getting heavier is partially to blame, since adipose tissue keeps the heat in. Or excessive cooling may be a form of conspicuous consumption—the wealthier the civilization, the colder the mall. Either way, allowing the set-point temperature of a large building to rise from seventy-two degrees to something like seventy-seven could mean substantial energy savings—on the order of twenty or thirty per cent, according to de Dear’s ad-hoc estimate.
Warmer, more thermally egalitarian offices will necessitate changes in work culture, including our notion of what an indoor climate ought to feel like. One of the godfathers of thermal comfort was a Danish engineer named Per Ole Fanger. Like many cold-weather natives, Fanger disliked too much noticeable movement of air—what you and I would call a draft. In warmer countries, though, such as Australia, air movement is a good thing: it’s a breeze. (“This thing about draft was all a bit of a beat-up, I reckon,” de Dear said.) Rather than cooling the air, which is energy intensive, facilities managers could make it move faster.
A second option would be to change our clo. In 2005, the Japanese Ministry of Environment created the Cool Biz program, which mandated that government ministries set their air-conditioning to eighty-two degrees during the summer to save energy. The M.O.E. invited workers to replace their ties with starched collars and their jackets with short-sleeved shirts. In two years, the program cut CO2 emissions by an estimated one and a half million tons. (Later, after the 2011 meltdown at Fukushima forced Japan to scale back its nuclear-power production, the government launched Super Cool Biz.) What is clear is that, even in the limb-numbingest indoor conditions, people prefer to dress in what de Dear calls a “climatically responsible” way. He mentioned a study that he and one of his graduate students, Craig Morgan, conducted in the Sydney headquarters of an international credit-card company in the early two-thousands. For the first four days of the week, Monday through Thursday, irrespective of season, the employees obeyed their dress code. Clo, in other words, remained static. On “mufti Fridays,” though, when employees had a choice of what to wear, they dressed seasonally. “We instinctively do it,” de Dear said. “We look out the window when we get dressed in the morning, as though that’s where we’re going to be spending our day.” Maybe the solution, then, is to make the indoors like the outdoors. It’s more warmth than Adam needs, but Adam can ditch the jacket and tie.
