Heat People, Not Buildings

Personal climate-control systems could be more energy efficient than keeping entire rooms at a single temperature.

Eric Gay / AP

Sometimes the most effective way to solve a problem is by addressing it more directly.

The U.S. spends 13 percent of its energy heating and cooling buildings, but much of that energy goes to changing the temperature where people aren’t. If the ceiling of an office maintains a perfect 73 degrees Fahrenheit but nobody is levitating there to feel it, does it make a difference?

Now, in response to a challenge from the Department of Energy, a cohort of engineers is tackling this wasted energy by designing new devices to control the temperature around individuals, not throughout entire buildings. Think of it like a swanky car’s climate control, but for the office.

There are a few different ways to do this, including high-tech undergarments, fan-equipped office chairs, and even a personal attendant robot that follows you around blowing hot air. These might sound a little far-fetched, but it adds up: The goal is to let buildings reduce their heating in the winter and cooling in the summer by 4 degrees, which would cut greenhouse-gas emissions in the U.S. by up to 2 percent. These aren’t just abstract ideas, either—working prototypes were featured on display at the ARPA-E Energy Innovation Summit outside Washington, D.C., this week.

Expanding Temperatures Saves 5-7 Percent HVAC Energy Per Degree Fahrenheit

This chart models the energy savings from setting the building temperature hotter or colder than usual. (Center for the Built Environment / CityLab)

People move around, so personalized comfort systems have to be mobile, too. That’s why a team at the University of Maryland built the RoCo or Roving Comforter—a miniature heat pump on wheels with an air nozzle on top. The robot zooms along behind its master, directing air of a desired temperature at his or her body. It’s capable of keeping people comfortable when the room is 4 degrees above or below normal room temperature, which can generate energy savings of 12 percent to 30 percent from heating and cooling compared to business as usual.

“There are lots of robots that follow, but most of them are still looking for something helpful to do. This one will do something productive,” says UMD engineering professor Reinhard Radermacher, the project lead.

The Roving Comforter may not injure a human
being or, through inaction, allow a human being to
experience thermodynamic discomfort.
(Julian Spector / CityLab)

RoCo will be of most use in low-density environments, Radermacher explains, like offices, factories, hospitals, and data centers (which still need humans to fix problems every once in a while). Long-term, the scientists envision expanding the personal-assistant capabilities. Since it's already heating and cooling things, why not have it serve hot or cold drinks? Or carry speakers and a phone charger? Hold your purse?

It will take at least a few years to gussy up the product and bring the price down for consumers. And there are some lingering questions. What happens when you reach a flight of stairs? Will an army of robotic minions buzzing around the office affect productivity? Can humans accept a permanent robotic companion?

Radermacher isn’t worried about that last one. “Usually the first reaction is a grin, so that made us go ahead, really,” he says.

Whether people will actually want to buy one is a different question. The RoCo team wants to meet ARPA-E’s goal of a $60 price tag—low enough to get at least a few skeptics to try it out for themselves.

A mannequin sports the Cornell team’s
temperature-controlled base layer beneath
formal attire. The RFID sensor is visible at top,
while the thermoelectric cooler hangs on
the belt. (Julian Spector / CityLab)
* * *

So maybe you read too much Asimov growing up and you'll never trust a robot with the intricacies of your daily life. Maybe you have simpler tastes, in which case, you might prefer some temperature-controlled clothing.

Ambient temperatures won't matter as much if you can control the heat of your base layer, so a team from Cornell University has whipped up a prototype to do just that. The mesh undershirt has a system of tubing, like capillaries across the torso, that carries air from the miniature compressor attached on the wearer's belt. The heat pump responds to an RFID sensor woven into the shirt with conductive thread, which reads heart rate, temperature, and perspiration so efficiently that it can draw all the power it needs from the air around it.

“Because this is the immediate layer to your skin, the response time is much, much faster than you cooling the air,” says Cornell electrical engineering professor Edwin Kan, who works on the project.

This device is worn, so it has to be comfortable. That’s the job for Tasha Lewis, a professor in Cornell’s Department of Fiber Science and Apparel Design. She’s been talking with potential users about their needs for the style and fit of the garment. For instance, where would the heating unit go on a woman who isn’t wearing a belt? Currently, the device is pretty bulky for something that hangs on your body all day, but is there a way to transform that device into a fashion statement in its own right?

The garment could be particularly appealing for menopausal women, Lewis says, because it can adjust to body temperature fluctuations within seconds. More broadly, it could be the special something you pull out for your most high stress situations—the big interview, meeting with a major client—or just when you don’t want to show up to work on a hot day sweating profusely.

“It’s our way to say, you can control how comfortable you are, wherever you are—even if you’re standing on the subway, or if you’re in your office, or if you’re just running,” Lewis says.

Elsewhere in adaptive clothing, a group from Otherlab, a private research institute in San Francisco, is designing fabric that expands and contracts based on heat, creating a thicker garment in the cold and thinner in warm settings.

Common materials like nylon, polyester, cotton, and spandex respond differently to changes in temperature, senior R&D engineer Jean Chang explains. The team combines different materials so that when exposed to a drop in temperature, the fabric puckers into a bunch of tiny dimples, which trap air and improve insulation. They’re still working on a clothing-sized prototype, and this technology is more promising for outerwear than for base layers, but it could be a great way to survive those days that switch from cool to warm before you get home to change. Or, for that matter, for an office that always wavers between comfortable and too chilly.

* * *

The most shovel-ready personal heating system at the ARPA-E convention was a magical office chair from the Center for the Built Environment at UC Berkeley. It looks like a typical upscale ergonomic chair. This model, though, has a heating element and a fan in both the seat and the back. A control panel on the side only turns on when someone sits down, at which point the user can independently control the bottom and back for their desired heating or cooling. If your back is sore, for instance, you could lightly warm it up while keeping your base cool.

Portable heating elements and fans already exist, but this chair trounces them in efficiency. Full heating capacity uses 14 watts and full cooling capacity uses 3.6. Compare that to many personal heaters on the market now, which use up to 1,500 watts. This efficiency matters for the system-wide greenhouse emissions: The solution to current energy waste can’t consume more than it saves.

Beyond the low energy demand, the chair has wi-fi and Bluetooth connectivity, so it can communicate with the building’s central heating and ventilation system. The chairs, then, promise a bounty of occupancy and behavioral data that in turn can help buildings run more efficiently. Knowing how many people are in a building at a given time will help operators more efficiently set the ambient temperature. And if they see everyone is heating up their chairs when the air conditioning is on, they can bump up the building temperature and save some energy.

PCS Chairs Improved Summer Comfort

The heating/cooling chair earned high marks for acceptability in field tests at a range of temperatures. (Center for the Built Environment / CityLab)

Creating a small sphere of comfort at the desk risks dissatisfaction when a worker leaves to walk around a warmer or cooler office. But the initial trials suggest this isn’t a big worry, says Edward Arens, the director of the Center for the Built Environment. It takes about 15 minutes for people to register discomfort from walking around in the heat, and that sensation vanishes within seconds of returning to the chilly chair-fans. The team’s field study found that, at a range of temperatures, people were much more satisfied with the special chair than with the conventional alternative. In fact, CBE researcher Hui Zhang adds, the subjects wanted to take the chairs home afterward.

“This is a win-win situation: You reduce the energy, but you also make people more comfortable,” she says.

Office comfort is big business, and a company called Personal Comfort Systems has acquired the rights to the chair and will handle commercial production. They’re calling it the Hyperchair, and for now, at least, they’ve been selling at $1,900 apiece.

There’s a strategic element to joining efficiency with comfort. For years, the two have been pitted against each other: You could indulge in luxury or cut back your energy use to lower your environmental footprint. Ultimately, Americans will need to make some tough choices about the energy their lifestyles demand. If large institutions can cut their usage with ultra-high efficiency tools that actually make people more comfortable, the energy savings could start before those tough choices get resolved.

This article appears courtesy of CityLab.