UC Berkeley-designed chair cuts energy use with personal thermal control

Carli Baker/Staff

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In an attempt to replace costly, often uncomfortable large-scale ventilation systems, UC Berkeley researchers have designed a revolutionary thermal-control system to cut energy consumption while improving user comfort.

The personal comfort system, adjustable on an individual basis, will allow users to maintain a certain homeostasis in a range of office temperatures. This flexibility drastically reduces the necessity of overzealous air-conditioning and heating units, thus cutting energy usage in the building by almost one-third.

Developed by researchers at the Center for the Built Environment, the system employs a host of energy-efficient devices like low-wattage fans and heat-radiating sheets that are discreetly embedded into office chairs and regulated by a control knob on the armrest. Supplementary units include a light bulb-powered foot warmer and an additional cooling fan.

According to Wilmer Pasut, a postdoctoral fellow at CBE who worked on the chair, 50 percent of global carbon dioxide emission is related to the building sector, a daunting yet approachable issue for researchers in his field.

“We really think that we can ‘change the rules’ and fundamentally rethink the way in which we condition our spaces and design for comfort,” Pasut said. He added that the chair only consumes 3.6 watts for cooling and 14 watts for heating, while common heaters in offices use about 1500 watts.

The chair, cordless and repowered via laptop charger, comes as the product of 15 years of research on the sensitivity of 16 different body parts. The team found that the most fundamental areas to regulate are the head, back and feet, each targeted by the PCS. During the development process, the team, supported by a $1.6 million dollar grant from the California Energy Commission, used a thermal mannequin to calibrate measurements of the cooling fan’s efficiency to these areas.

According to the study, researchers who conducted human subject tests found that people using the PCS were able to stay comfortable in temperatures ranging from 64 to 82 degrees Fahrenheit, while most conventional ventilation systems maintain a stricter range of only 71 to 75. In tests around the country, for every degree Fahrenheit for which the PCS could compensate by using “ambient” air, energy consumption was lowered by seven to 14 percent.

“In America, air conditioning is too dominant — we really overcondition, even in the cool Bay Area,” said Hui Zhang, a researcher at CBE. “So you have to have something. Otherwise, how can you change anything when that’s how things have been operating for so long? The PCS is how to penetrate that.”

Although Zhang says everyone “loves the chair” and the chair is a potential breakthrough in promoting sustainability, some are still hesitant to assume an inevitable success.

Alastair Iles, an assistant professor of environmental science, policy and management who specializes in technology development and its implications for society and the environment, says though he is impressed by the design and its dismissal of a “one-size-fits-all” approach, he maintains mixed feelings about its practicality.

“My concern is that the chair is an elaborate, potentially costly approach to solving an energy conservation challenge,” Iles said. “There may be various building designs that are more modular, are cheaper and provide feedback to users.”

But Zhang upholds that including users in the conversation is the focus of the project. The fans used in the system are equipped with USB ports to remotely send data about personal usage that, combined with information like ambient temperature and others’ responses, will be aggregated to set the more conservative energy standard for the building’s ventilation units, Zhang said.

Both Iles and Zhang note that an obstacle in commercializing the product and getting a full patent for manufacturing is finding a developer who is willing to install the chairs. Zhang hopes to gather enough positive user feedback to provide incentives for manufacturers, and colleague Pasut says the researchers “definitely see the technology being massively adopted.”

“It’s not that easy because engineers are really rigid about design,” Zhang said, “but we provide something that works — we provide satisfied people. Energy is my issue; this is really exciting, and it really works.”

Virgie Hoban is the lead research and ideas reporter. Contact her at [email protected][email protected] and follow her on Twitter @VirgieHoban.