It’s summertime for half the world. On these, the hottest days of the year, office workers huddle under blankets. Complaints trend on Twitter with posts like, “I could preserve dead bodies in the office it’s so cold in here.” And style bloggers offer advice for layered looks for coming in and out of the cold.
Why are America and so many other places so over air-conditioned? It seems absurd when you consider the money and energy wasted. Architects, engineers and energy experts sigh with exasperation when asked for an explanation. They tick off a number of reasons – probably the most vexing is cultural.
“Being able to make people feel cold in the summer is a sign of power and prestige,” said Richard de Dear, director of the Indoor Environmental Quality Laboratory at University of Sydney, Australia, where excessive air-conditioning is as prevalent as it is in the United States. He said the problem is even worse in parts of the Middle East and Asia.
Commercial real estate brokers and building managers say tenants specify so-called chilling capacity in their lease agreements so they are guaranteed cold cachet. Luxury stores are kept colder than more down-market ones.
There’s also the misconception that colder temperatures make workers more productive when, in fact, research shows the opposite. Studies have shown people work less and make more mistakes when the air temperature is 20 to 22 degrees Celsius versus 23 to 24 degrees. Some research indicates feeling cold can take a psychological toll, making people untrusting.
The problem is compounded by building managers who, surveys indicate, typically don’t adjust the temperature higher in summertime when people wear lighter clothes.
Air-conditioning systems are also usually designed for worst-case scenarios – full occupancy on the hottest day of the year. As part of that calculation, designers might have factored in older computers and less energy-efficient lighting that radiate much more warmth than the machines and bulbs used today. And, engineers say, they might add a 20 percent upward correction, just to be on the safe side.
“It’s analogous to a high-tune car where you have to keep your foot on gas to keep it from stalling out,” said Edward Arens, a professor of architecture at the University of California, Berkeley.
Paradoxically, another reason for aggressive air-conditioning is energy-efficient building construction. Better sealing and insulation keeps air-conditioning from entering. So cool air is often kept blasting to meet mandated air quality standards for levels of carbon dioxide that build up in the absence of outside air. The cool air also controls humidity, which can lead to mold.
While architects like Mr. Arens point the finger at engineers for designing air-conditioning systems with too much capacity, engineers point the finger back at architects who often have an aesthetic aversion to thermostats.
“Architects try to convince mechanical engineers to hide sensors so they don’t mess up their beautiful design,” said Jon Seller, general manager of Optegy, an energy management consulting firm based in Hong Kong that specializes in air-conditioning systems. As a result, he said, sensors wind up in out-of-the-way places like air inlets on the ceiling, where, because heat rises, they provide less than accurate readings.
Computer scientists have developed a smartphone app that making people the thermostats. Users can tell the app, called Comfy, whether they are hot, cold or just right. It learns trends and tells the system when and where to throttle up or throttle back the cooling. The developers claim Comfy-equipped buildings realize savings of up to 25 percent in cooling costs.
“We have a lot of data that people are most comfortable if they have some measure of control,” said Gwelen Paliaga, head of a committee that develops standards for thermal comfort for the American Society of Heating, Refrigerating and Air Conditioning Engineers.
Of course, for fresh air and comfort, engineers and architects tend to agree the most effective control is being able to open and close the windows. No app required.