Adding skylights is another popular method of daylighting, especially in interior rooms. In fact, a skylight admits three times as much light as a similarly sized vertical window, and the light is more uniform because it comes from above rather than from one side. However, Baczek points out that skylights are windows. "In a house in a heating climate, there's more heat loss through the ceiling than there is through the wall," he says. "If I put a skylight in, I’ve upped the ante on heat loss." Choosing energy-efficient skylights and installing them carefully helps minimize heat loss.
As with vertical windows, placement of skylights is important. "One of the most effective ways of daylighting the interior of a house, if you have a sloped roof, is to place the skylight near a vertical wall that is painted white" says architect David Bennett of DJB Architects LTD."A white wall is probably one of the most efficient ways for redistributing daylight through a room as soft, unfocused light."
"Switchable glazing" is an exciting new technology for dramatically improving the efficiency of both windows and skylights. Various treatments of glass allow its transparency to change in response to a small electric current or even in response to sunlight itself.
Bending the light fantastic
Also known as a tubular skylight, a solar tube can bring overhead daylight into rooms where a skylight is impractical. A solar tube consists of a domed lens that collects sunlight on the house roof, a cylindrical tube (10-20 inches in diameter) with a highly reflective interior surface to transmit the light to ceiling level, and a translucent lens that diffuses the light into the room. The tube can bend and carry light around barriers such as roof trusses. A solar tube is more effective than a skylight for an interior room under a sloped roof, which might require a shaft at least 5 feet deep. Some brands, such as Solatube, can be equipped with a dimmer accessory to control the amount of transmitted light.
Because daylighting saves energy and provides a more attractive, comfortable environment, development is under way on innovative technologies. For example, Steven Winter Associates has developed a rooftop device that tracks the sun and transmits daylight into the home through optical cables as unobtrusively as conventional wires carry electricity and cable TV. The flexible "light pipe" winds through ceilings and walls to a diffusing light fixture as much as 50 feet away. A 10-square-inch rooftop collector and a bundle of four 1/2-inch-thick plastic cables can focus and transmit enough sunlight to provide illumination equivalent to a 100W light bulb.
Sunlight may be free, but it takes careful planning to use it effectively in our homes. Fortunately, many resources are available to support that planning. Strategies for sizing and placing windows and skylights can be refined to reflect regional climate characteristics. Technological developments are improving traditional materials and providing new options.
Whether building or renovating a house, it is now possible take advantage of natural light to reduce energy costs and enhance the comfort and appearance of every room. These new tools would surely have pleased Frank Lloyd Wright, who said, "The best way to light a home is God’s way."
Freelance writer Loretta Hall can be contacted through her Web site, SubsurfaceBuildings.com.
