Marilyne Andersen, trained as a physicist, spends a lot of her time thinking about…daylight. If that seems counterintuitive, it’s not. As electromagnetic radiation, light is subject to all the physical laws connected with that phenomenon. Equally pertinent, both sunlight and its most obvious product, daylight, are highly relevant to a secure energy future.
In the U.S., she notes, “buildings represent about 40 percent of total energy consumption, and lighting is 15 to 40 or more percent of that.” If you add in heating and cooling — obviously related matters when the issue at hand is buildings and sunlight — the potential for efficiencies is that much greater.
Andersen’s exploring sophisticated ways for taking maximum advantage of sunlight and daylight. In isolated cases, architects and builders have already proceeded well along that path. There’s a Swiss office building that has virtually no heating infrastructure, instead exploiting sunlight, shade, natural ventilation, and heat-collecting masses integrated into the building’s structure to control temperatures. “Its energy costs are five percent of those of similar-sized conventional buildings,” says Andersen, an MIT assistant professor of building technology and member of the School of Architecture and Planning. “It’s amazing.”
So why are most buildings energy wastrels? It’s both a lack of incentives and a lack of an understanding how to make smarter use of resources like sunlight, says Andersen. There are also the potential extra construction costs involved in improving ways of introducing natural light, and making optimal use of it once inside.
Take something as basic as the louvers employed in many windows. “There’s a school in Europe,” notes Andersen, “where the louvers direct the sunlight towards massive concrete structures in the ceiling.” Result: the structures retain the heat in summer, so the classrooms stay cool. On sunny winter days, meanwhile, the stored heat helps warm the building.
One obstacle to wider use of such methods is that calculating how a particular type of blind or window glass will work in specific circumstances is tough, requiring complex studies of exactly how the light will behave on its way into, through, and beyond a window. “It’s a very time-consuming process,” notes Andersen, “and that makes it expensive.”
Andersen and her students are doing the basic work needed to simplify the process. For example, they’re building a device equipped with a sophisticated, ellipsoidal light-gathering surface that will let users do one-shot analyses of the light-related behavior of window or Venetian blind materials.
The instrument, an adaptation of a device used in computer graphics, is mainly a research-and-teaching tool, but could help set the stage for commercial variants. Meanwhile, the faculty member’s working on a range of other techniques for taking maximum advantage of daylight in buildings. Among her interests: light-redirecting devices, the better integration of daylight into architectural design tools, and the impact of different types of light on human health, comfort, and vision.
The efforts have real potential. Andersen says that in commercial and educational buildings, especially, more reliance on daylight could cut electricity use by up to 80 percent with minimal loss in comfort or convenience.
So that’s one motivation for her work. Another is that it’s fascinating. Andersen says that when considering a career, she had trouble deciding between architecture and physics. So, she’s doing both. “When I can stop and sort of listen to myself talking about my work,” she says, “I’ll say, ‘Wow, that sounds really interesting.’”