Lisa Heschong is a principal with Heschong Mahone Group, a Fair Oaks, Calif., consulting firm specializing in building energy efficiency policy. As a researcher, she led the teams that analyzed the impacts of daylighting on human performance for the renowned “Daylighting and Productivity Studies.” A licensed architect, she currently serves as chair of the subcommittee on daylight metrics for the Illuminating Engineering Society of North America. She earned a BS from the University of California, Berkeley, and a master's in architecture from the Massachusetts Institute of Technology.
BD+C: How did you get interested in the indoor environment?
Lisa Heschong: Early in my career, I wrote a book called Thermal Delight in Architecture [MIT Press, 1979]. It explored how people's relationship to buildings was influenced by the thermal qualities of those buildings, on not only a physical level, but also on sensual, emotional, and cognitive levels. I got very involved in passive solar design, and realized that I was not only designing the thermal qualities of my buildings, but also the luminous environment.
BD+C: Your studies indicate that people naturally gravitate toward the light, don't they?
LH: We have long been saying that humans are “phototropic”: they will usually choose to face the lightest area of a room. Why? In our studies of a call center, we could detect that people with more tenure tended to select desks closer to the windows. However, since we had such a variety of conditions, we could also isolate how their performance was associated with exposure to view. All other things being equal, the bigger the view, the faster the worker's performance. We also saw indications of the importance of view on performance in our studies of schools and of professional office workers. Many other researchers have had similar findings.
BD+C: So “having a view” is important to human performance?
LH: Personally, I have become convinced that access to views of the outdoors is essential for human beings working or living inside buildings. My current hypothesis is that looking out a window is people's primary means of circadian stimulus during the day. Frankly, I didn't go out looking for that subject area, views. It was just something that was added as a control to our studies on daylight.
But it became the dominant predictor of performance, consistent across all our studies. In our most recent schools study, any kind of “better” view was always associated with better student performance. The “better” view included bigger windows, distant views, seeing vegetation, seeing activity, even parking lots or playgrounds.
BD+C: Any other benefits from outside views?
LH: In our Desktop Study, we found that office workers who had outside views reported fewer headaches and less fatigue during the work week. They also had fewer complaints about everything else about their physical environment. Even though people who were nearer windows had measurably more extremes of temperature and light and more noise, they had fewer complaints, whereas people at the [building's] core had the most complaints about noise, temperature, ventilation, and lighting.
BD+C: What new research do you find intriguing today?
LH: The new medical research on the importance of light to our basic physiological functions. Daily patterns of light and dark control our circadian rhythms, an elaborate symphony of hormones and neurotransmitters and immune functions—which determine how we feel, how well we think, even our core body temperature. When your circadian system is out of kilter, you feel strange—like jet lag—and often have complaints about your environment. For example, you might feel too cold or too hot, even if the room temperature is within the comfort norm. I think people complain a lot about temperature because our bodies send up mental alarm signals when our core body temperature starts to shift. We don't have those kinds of internal alarms for poor light exposure, even if it might be the more fundamental cause.
BD+C: What does all this suggest about design?
LH: From a broad sweep, the point of designing buildings is to support the activities of [people], so making them productive, happy, and healthy has to be our primary goal. The original rationale for licensing architects was to protect the public health—things like structural safety, urban setback requirements, and ADA. Now we have information that shows that daylight and views make a difference in human well-being, we should make sure they are available to people inside our buildings.
BD+C: So what do you recommend?
LH: I would like to see a requirement in building codes for minimum access to outside views for workers and students. That exists in Europe—workers can be no more than seven meters from a window—and it needs to be reimplemented in the U.S. I say “reimplemented,” because, for example, there used to be a requirement for daylight in schools in California in the 1950s, but that got dropped. Today, the only place in California where daylighting is required is in prisons.