Arens discusses personal comfort systems

The core philosophy of personal comfort systems is to “address the person directly and not the whole space,” said Dr. Edward Arens. Arens is Professor Emeritus of Architecture at the University of California, Berkeley and the director of the Center for Environmental Research. His work with personal comfort systems is closely tied to the Center for the Built Environment at Berkeley.

An initial personal comfort system that Arens introduced to the audience was designed for office spaces. It consisted of a motion-sensitive fan, a foot warmer that uses reflective red and orange light bulbs to warm the individual’s feet, and a heating and cooling chair.

When dealing with temperature and humidity changes that make an individual more or less comfortable in their work areas, it is “100 times more efficient to condition the person directly,” said Arens.

Field tests have also demonstrated that personal comfort systems can reduce energy costs by as much as 60 percent, while rendering 90 percent of people comfortable using just the specialized chair and desk fan.

While developing personal comfort systems, Arens also emphasized the importance of being able to target the right body parts. He cited a study in which high pressure air was applied to different parts of people’s bodies while observing the thermal character of their reactions.

“What’s interesting about these results is that under cool conditions, it’s one set of body parts that dominates, and in warm conditions it’s another set that dominates,” said Arens.

In cold conditions, the extremities — including feet, hands, and the head — experience discomfort first, while in warm conditions, the face is more receptive to discomfort. By targeting these areas appropriately according to varying conditions, increasingly useful personal comfort systems can be created.

The heating and cooling chair, for example, uses heated resistance wire to raise an individual’s body temperature and targeted convection currents to bring down a person’s body temperature.