When you’re inside a building, whether it’s snowing or sweltering outside, the internal temperature probable only varies by four degrees. The Department of Energy says that, in practice, most offices, hospitals, houses and other buildings are kept between 71 and 75 degrees Fahrenheit to keep people comfortable.
“It’s really kind of ridiculous that we heat and cool a whole building for the comfort of a few people who don’t actually occupy that much space,” says Ellen Williams, the director of ARPA-E, the Department of Energy’s Advanced Research Projects Agency-Energy.
Heating, ventilation and air conditioning (HVAC) account for 13 percent of overall American energy consumption, and 40 percent of the energy used in a typical U.S. residence. To address any waste, ARPA-E started the DELTA (Delivering Efficient Local Thermal Amenities) program, which funds projects that design what they call localized thermal management systems. The idea is that if we can better regulate our personal body heat through things like wearables and targeted heating systems, we can use less energy to keep buildings at a comfortable temperature.
Some of those projects, like T-shirts lined with tiny fans, might seem far-fetched, but researchers have proven these concepts have the potential to cut a measurable amount of energy use. Emily Fritze, special advisor to ARPA-E’s director, says these kinds of technologies could potentially save 2 percent of the overall energy used in the U.S. The DELTA projects were on display at the recent ARPA-E Energy Innovation Summit. Here are some of the options that are closest to being in your closet or at your desk:
A Temperature Regulating Robot
RoCo, or the roving comforter, is a moving robot that regulates the temperature in your personal space. To follow you around, it tracks your phone, and then it blows hot or cool air at your face and feet. The idea is that by creating a bubble of heat or AC, you significantly reduce the HVAC waste that comes from heating, say, empty conference rooms. The tricky part in developing the RoCo wasn’t the tracking, which uses Wifi and face recognition, it was finding a way to dump the excess heat when the AC was cranking (think, the condensation on a swamp cooler). To address that, the University of Maryland team built in a canister of paraffin wax, which melts and acts as a heat dump when it gets hot. The RoCo can run for two hours, then the wax needs to resolidify. The researchers expect to have prototypes ready by April, and, through a partnership with GE, they hope to have commercial models, at a price point of about $60, available by 2018.
A Heated (and Cooled) Office Chair
Researchers at University of California, Berkeley, think they can control temperature more efficiently by hitting your backside. They’ve designed an office chair that has fans and heating coils built into the seat and back, to maintain a temperature between 61 and 84 degrees Fahrenheit. The chair has pressure sensors, so it only turns on when there’s a butt in it. When it’s on full blast, it uses just 14 watts of power to heat and 4 watts to cool. The team already has a working prototype that runs off a power cord. But, to make sure the furniture piece is functional and easy to use, they are designing a version that doesn't have to be tethered to the wall. The group is working with WiTricity to charge the chair through Wifi, so a user can roll anywhere.
Air Conditioned Clothing
A group from Cornell is pairing fabric and wearable electronics to develop thermoregulating clothing, with tiny air blowers inside microtubes woven into the fabric. Temperature sensors trip the fans, which blow warm or cool air depending on the temperature variation occuring. The tricky part is incorporating movable electronics into a piece of clothing, but the researchers say they can put moving electronics into an undershirt in a way that doesn’t compromise washability or safety. “We have demonstrated the conceptual prototype and filed two patent applications, but before commercialization, the entire system should be optimized,” says Jintu Fan, the project lead. “We think this will take another two years.”
Footbeds That Cool Your Heels
The nonprofit research institute SRI International has targeted parts of the body—the glabrous, or non-hairy, skin on you palms, face and soles of your feet—that have high densities of blood vessels, and thus transfer heat more effectively. Focusing on those zones, researchers have developed a thin material to go in a shoe or a glove that is lined with channels for cold water. The water is pumped through the system and cooled as it runs past a tiny fan. It’s hard to get something that complex flat enough to fit in a shoe or a glove, but the researchers have developed a work boot called the ReBoot, which uses the material as in insole. They also want the material to be a low-impact, low-cost addition to your existing wardrobe, so after the ReBoot, they’re going to work on insoles that should be able to fit into shoes you already have.
Clothes That Change Thickness
Another thermally adaptive fabric idea comes from Bay Area technology design firm Otherlab, which is focused on changing the density of fabrics passively, meaning without electronics. To make, say, sweaters that get thicker when you get colder, they weave together two different thermally reactive materials, which expand at different temperatures. “As temperature changes, the lengths of the two materials change differently, inducing a bend in the pair that, in a textile structure, can bring about a change in thickness,” says Brent Ridley, the head of the project. He and Otherlab co-founder Saul Griffith have been toying with they idea of pairing dissimilar materials for years (since they were in grad school), because they thought it seemed like an elegant solution to the heating problem, though they have only been actively working on it for about 18 months. Ridley says they should have a material prototype in just over a year, and then they plan to test and manufacture it. He sees schools or factories, where people wear uniforms, as ideal places to test this kind of technology.