Energy-Efficient Lighting Design
Here's how igh-performance lighting helps make homes look better, helps with visual tasks and also can reduce the home's energy use.
High-performance lighting - lighting that's efficient and relates well to the design of the house - helps make homes look better, helps with visual tasks and also can reduce the home's energy use.
However, don't expect to simply install energy-efficient fixtures and save bundles in energy costs - the biggest energy savings come as part of an effort to improve the performance of the entire house, including increasing insulation, installing high-performance windows, sealing air leaks, sealing supply and return ductwork, and installing a high-efficiency furnace and air conditioner. Benefits increase when all these improvements are considered together: For example, more efficient lighting reduces the air-conditioning load. Also, the Department of Energy groups appliances with lighting when looking at energy use. If you're focusing on lighting, consider replacing old appliances with energy-efficient ones: The most efficient appliances on the market are labeled Energy Star.
While the lighting strategy you choose depends on the level of remodeling you're doing, these design principles hold true.
1. Focus your effort on rooms used most. Improving the lighting in these rooms will make a lot of difference.
2. Replace existing fixtures. Most homes have incandescent fixtures. Replace them with dedicated, hard-wired fluorescents. If you use screw-ins, they may be switched back to incandescents when the bulb burns out, losing the efficiency benefits. Hard-wired fixtures may have better aesthetics and light quality, too.
3. Layer lighting for maximum impact. To produce dramatic effects, design ambient, task and accent lighting. Ambient lighting provides general room illumination and may reduce the need for additional portable lighting. Task lighting helps homeowners see better where they need it - under-cabinet lighting in the kitchen to help in preparing meals, for example. Accent lighting adds sparkle by focusing on an architectural detail such as a fireplace or on photos or artwork.
In the photo above, the kitchen is lit by a low-quality fluorescent fixture (128 installed watts). The result is a dreary room with little character. In the photo below, under- and above-cabinet high-quality fluorescent lighting (140 installed watts) provides excellent indirect light for the entire kitchen with complementary task light on the counter.
4. Consider the room's function and form. No matter where you start, con-sider which activities are most important for the room. Perhaps the easiest place to begin is the kitchen. As stated above, under-cabinet lighting provides task lighting. When there is space above kitchen cabinets, between cabinet and ceiling, it's easy to mount inexpensive strip lights to provide excellent, glare-free light for the entire room. A recessed downlight over a kitchen island will accent the island, help the homeowner see better when performing kitchen tasks and provide ambient light.
For the family room, use a combination of ambient, track and portable lighting. Use a reduced level of ambient light in the home office to avoid glare on computer screens. In the bathroom, both appearance and safety are important. At the vanity, light from either side of the mirror, as well as the top, to avoid shadows.
Also consider the room's design. "Integrate lighting logically with the architectural characteristics of the room," says John Holton, an IBACOS researcher. "For example, cove lighting that illuminates raised ceilings and valance lighting above windows provides general illumination while relating well to specific architectural features and gives the room nice character."
5. Use concealed light sources. Homeowners will notice the illuminated floors, walls and ceiling of the room instead of the light bulbs. Concealed light sources help eliminate direct glare from lamps.
6. Use fluorescents. According to DOE research, fluorescents use 25 percent to 35 percent of the energy used by incandescents to give the same light output and last up to 10,000 hours, compared with 1,000 for the typical incandescent bulb. Using a mix of fluorescents and incandescents is likely to be less efficient than using all fluorescents. Based on preliminary research findings from Building America team member Steven Winter Associates, homes with compact fluorescents (CFLs) installed only in certain areas (usually kitchens and hallways) use more energy than homes with 100 percent CFL lighting.
Most people associate fluorescents with the harsh, bluish lighting typically found in garages. For a nice, crisp light - quality as good as incandescents-choose fluorescents with a color temperature of 3,000 degree Kelvin, with a color rendering index (CRI) of 80 or greater.
Also, choose electronic ballasts for both linear fluorescents and CFLs. Electronic ballasts provide a better quality light and are more energy efficient. They don't hum, last longer and eliminate the turn-on delay typically associated with fluorescent lighting.
7. Limit the number of different light sources. For linear fluorescents, only use two different ones (3 foot and 4 foot), and for CFLs, only use three: 15, 26 and 32 watts. This makes it easier for homeowners to replace the lamps.
8. Consider controls. "Controls such as photo sensors, occupancy sensors, dimmers and remote controls may help to reduce energy by ensuring that lights are only used when needed," says Subrato Chandra, a researcher at Florida Solar Energy Center.
IBACOS (Integrated Building and Construction Solutions) is a research and consulting firm specializing in building science. IBACOS is a member of the DOE's Building America Program, which supports research on remodeling homes to save energy while improving health and comfort.
A range of fixture types are available to implement high-performance lighting. The list below includes fluorescent fixtures using either linear lamps or CFLs. Many are available as
Energy Star fixtures, which meet strict energy-efficiency guidelines set by the U.S. Environmental Protection Agency and the DOE.
Recessed downlights provide indirect lighting by shining onto the floor and room furnishings. Wall washers are recessed downlights with a reflector or lens to illuminate a wall.
Recessed downlights and wall washers: A common way to offer concealed source ambient lighting, recessed downlights and wall washers provide indirect illumination through reflections from the floor, walls and furnishings. These ceiling-mounted fixtures come in sizes ranging from 13 to 42 watt. Reflectors are available in highly reflective aluminum (Alzak) and white. Recessed downlights also may have black/white baffles and several types of lenses. Many of the lensed fixtures are suitable for use in wet locations such as bathrooms.
When recessed downlights are installed in insulated ceilings, heat can build up, significantly reducing lamp and ballast life, as well as reducing light output. The DOE's Emerging Technologies Program at Pacific Northwest National Laboratory is researching new technologies for reflector-type (R-lamp) CFLs installed in recessed downlights located in insulated ceilings.
Cove lighting above kitchen cabinets provides general room illumination.
Under-cabinet lighting, like these installed in a kitchen, helps with tasks like meal preparation.
There are many attractive designs for ceiling- and wall-mounted fluorescent fixtures.
Coves and valances: Built-in lighting coves in cove ceilings or above kitchen cabinets use inexpensive T-8 (1 inch in diameter) or T-5 (5/8 inch in diameter) strip lights and provide a wash of light across the ceiling. Valances, located above windows, also employ strip lights and illuminate both up the wall and onto the ceiling as well as down around draperies.
Under-cabinet lights: These long, thin fluorescent fixtures are mounted underneath wall cabinets and above work surfaces. They typically are found in kitchens and other work areas. The best light output is offered by the newest designed fixtures that use T-5 lamps of 14 watt, 21 watt and 28 watt in fixtures of nominal 2-, 3- and 4-foot length. These offer higher brightness and better light color quality.
Surface lighting: There is a vast array of surface-mounted linear and CFL fixtures. These range from very utilitarian 1x4-foot garage lights to detailed round, square and rectangular ceiling- and wall-mounted fixtures. These fixtures may use linear T-8 or T-5 lamps, circular lamps or CFLs.
Pendants: There are a limited but growing number of fluorescent pendant fixtures offered by manufacturers. They range in size from mini-pendants (5 inches in diameter) to much larger designs (24 inches in diameter and larger). Because they're exposed fixtures, choose a style that is compatible with the room.