Efficient Home Lighting Choices: Page 4 of 4

Intermediate

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Lighting Examples
Informational lightbulb packaging
Lighting packaging usually gives you all the data you need.
DOE lighting facts
Some products will bear the U.S. DOE’s Lighting Facts label, which helps identify a bulb’s characteristics, such as light output, efficacy, and color rendering.
Compact Fluorescent examples
Incandescent examples
LED examples
LED bulbs in stores.
LED lighting for many applications is now available at your local hardware store.
Beam angle matching
Matching beam angle to the lighting task is important—wide for area and ambient lighting, or narrow for task lighting. Until recently, LEDs were hampered by narrow beam angles, but that is changing.
Lighting Examples
Informational lightbulb packaging
DOE lighting facts
Compact Fluorescent examples
Incandescent examples
LED examples
LED bulbs in stores.
Beam angle matching

Most down-lights are designed to accommodate particular reflector lamp shapes and sizes. PAR (parabolic aluminized reflector) lamps work best in deep ceiling cans and R (reflector) lamps work better in shallow ones. The diameter of the opening tells you what size of bulb to purchase. If the opening is a little less than 5 inches in diameter, a PAR 38 works well (the 38 refers to 38-eighths of an inch in diameter, or 4.75 inches). PAR 30 or PAR 20 bulbs tend to work better in smaller openings. Bulged reflector (BR) bulbs will also fit in the same ceiling cans, but tend to have very poor efficiencies, in part because their reflectors do not do as good of a job at gathering and aiming the light. The reflector lamp technology you choose is also application-specific. In general, CFL reflectors are not a good choice—their light is too diffuse. The most efficient halogen technologies can be a reasonably good choice, particularly IR halogens. LEDs are the most efficient choice, though still a bit expensive. Their directionality and dimming capability give them some natural advantages in this application, and their long lifetimes (20,000 hours or more) can be a plus, given the relative inconvenience of reaching and replacing many down-lights.

A wide variety of specialized lighting applications are not commonly served by the three major lighting technology types. If you want to distribute light uniformly over a very broad area, for example, it’s hard to beat linear fluorescent lamps for affordability and for even light distribution. Some manufacturers have begun producing linear LED “tubes” that can be inserted in place of these fluorescent lamps, but most still struggle to compete with the uniformity of linear fluorescent lighting at a reasonable cost. Linear fluorescent tubes that were 1.5 inches in diameter (T12s) have now given way to 1-inch-diameter lamps (T8s) and even 5/8-inch-diameter lamps (T5s), for improved efficiency and performance (see “Changing Fluorescents to LEDs”).

Efficient Lighting for Efficient Homes

Using the most efficient lightbulbs is especially important in zero net-energy (ZNE) homes or off-grid homes powered by renewable energy systems. The extra energy saved by using LEDs compared to CFLs, for example, is also cost-effective when compared to more PV modules and equipment for meeting the larger overall loads (see “Save on PV” sidebar).

LEDs also offer a wider range of color choices than CFLs, making them a more seamless integration with passive solar homes that rely largely on daylighting. For instance, using LEDs with a CCT between 3,000 K and 3,500 K in rooms with good natural light will help keep the light color more similar as the lights come on in the evening. Likewise, some LEDs shift their color temperature as they are dimmed, making them a good match with solar homes that get flooded with “warm” temperature sunlight at sunrise and sunset.

Purposeful Lighting

My recently completed ZNE house in Durango, Colorado, uses LEDs in almost every fixture, inside and outside. Linear T5/fluorescent lighting is used in the laundry room and master closet, and pin-based CFLs are used in one ceiling fan. Incandescent lamps are used in only a handful of aesthetically critical applications like the red glass and seashell mosaic pendant lamps over the kitchen island, the fully dimmable dining room fixture, and the small, wall-mounted reading lamps next to our bed, where the extra warmth of the light’s appearance is worth the energy-efficiency trade-off. Our brains interpret red light—similar to the light from a flame or a sunset—as a cue to go to sleep. By contrast, our brains interpret blue light from CFLs or most LEDs—similar to the light from a TV, computer monitor, or cell phone—as a cue to wake up.

While the lighting in most homes can consume 1,200 to 1,800 kWh per year or about 15% of total electricity use, our estimated lighting energy use is only about 400 kWh per year. The light source we used most widely in the house was the Cree screw-based 800-lumen LED, purchased for $10 to $13 apiece. We also relied heavily on a new type of Sylvania LED down-light that surface-mounts directly to electrical junction boxes in new construction, eliminating the need for a down-light fixture or its penetration through the insulation. These fully dimmable products were about $35 apiece, and distribute the light very evenly and unobtrusively into the room. High-quality Soraa LED MR-16 bulbs are used in low-voltage track light fixtures.

Besides its energy savings, our energy-efficient lighting looks warm and welcoming. On a public tour of the house last spring, the most common remark we heard from visitors was how pleasant and attractive the lighting was. We should never forget that a lightbulb’s primary purpose is to provide excellent light. No matter how much energy they save, they will never gain widespread acceptance unless they light up a room attractively as well.

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