Kitchens Bustle with Efficient Lighting Opportunities
The kitchen is more than just a place to cook and eat. It often serves as the administrative and the social center of the home. Because it opens for business before dawn and closes long after sunset, the kitchen uses a lot of energy for lighting. That makes this room an important place to use efficient lighting. In a new kitchen or a remodel, you have the perfect opportunity to create a highly efficient lighting system.
In their 1994 trend survey, the National Kitchen and Bath Association reported that typical incandescent lights were used in 62 percent of the kitchen jobs. Fluorescents were used in only 45 percent. This indicates ample opportunity to use more fluorescents in kitchen projects. Currently, fluorescent lights are the most efficient source of light suitable for residential use. Full-size fluorescent lamps, often called "tubes," convert electricity to light with four times greater efficiency than typical incandescent lamps.
Compact fluorescent lamps (CFLs) are two to three times more efficient than incandescents. Their smaller size makes them easier to fit in places normally occupied by incandescents. Recently, manufacturers have introduced 35- to 40-watt CFLs with light output similar to a 150-watt incandescent.
Fluorescent lamps need a ballast to provide the proper electrical input. Electronic ballasts use less energy than magnetic ballasts. They also operate at a higher frequency which eliminates the flicker and hum sometimes associated with fluorescents. Electronic ballasts have been known to emit radio frequency waves that interfere with electronic devices such as telephones and televisions.
Incandescent lamps burn for only about 1,000 hours and halogens last between 2,000 and 3,000 hours. Compare that to CFLs, which last 8,000 to 10,000 hours and full-size fluorescent lamps at about 20,000 hours. Fluorescents' long service life makes them a good choice for locations where replacing expired lamps is inconvenient or even dangerous. Longer life and energy savings are good reasons to use fluorescent lights whenever appropriate.
Long ago fluorescents had a reputation for providing poor quality light. That changed roughly 10 years ago when lamps with improved color characteristics became widely available. You can easily avoid the color pitfall by paying attention to two numbers. The first is color temperature, expressed in degrees Kelvin (K). Most people associate indoor light with the "warm" look of incandescent lamps at 3000K or below. Fluorescents for indoor use should have a color temperature of 3500K or less. The second number is the Color Rendering Index (CRI), which indicates how accurately the light displays colors. Always select lamps with a CRI above 80. Since each manufacturer has a different designation for color properties, it may be difficult for you to tell by looking at the packaging. However, the manufacturer's product literature will often provides the information. All manufacturers of fluorescent lamps supply products with good color characteristics. However, you can't always find these products in retail home centers.
Efficient lighting starts with good design. Begin with task lighting for countertops and other work areas. Then think about general background light.
Put Light on Task Areas
Full-size fluorescents can be mounted under cabinets so the light shines directly on the counters. The long lamps spread light evenly across the work area. However, fluorescents can't concentrate light on a small spot. Specially designed under cabinet fixtures may be flat, but they need a bit more room than cabinets typically provide. The cabinet maker can accommodate this extra thickness by making the face frame an inch or two wider at the bottom. T-8 lamps have a narrower profile that fits more readily behind the cabinets face frame, although you may still need to ask for cabinet adjustments. For very tight spaces, look into fixtures that use T-5 lamps. Unfortunately, these are not available with a high CRI. Almost every kitchen has a light over the sink. This is the perfect application for a compact fluorescent lamp (CFL). If buying a new fixture, choose one made specifically for a CFL.
Recessed lights above counters can also provide good task light. If you install recessed lights in an insulated ceiling, you should take care to avoid the perils described below.
General Background Light
With all the task lighting in kitchens, a general background light may not be needed. For example, well placed recessed lights over the counters may provide ample general light. On the other hand, fluorescent lights mounted under the cabinets may leave the kitchen in need of more general light. If installed, the general light should use a fluorescent lamp and have a separate switch. It could be a surface-mounted fixture, a "cove" light mounted on top of the cabinets or a luminous ceiling.
Only 10 percent of the electricity that enters an incandescent lamp comes out as light. The rest is heat that must often be removed with air conditioning. Because they are so inefficient, incandescents should be used primarily for accent light, task light or dimming circuits where fluorescents are too expensive.
Although up to 30 percent more efficient than other incandescents, halogen lamps are still less efficient than fluorescents. Their main advantage is a crisp white light and better control of the light beam. Halogen PAR lamps and the low voltage MR16 lamps are the perfect choice when you need to direct light to a certain spot for accent or task lighting.
Imagine that you had only one light switch for the whole house. That would force you to use too much light in the wrong places. Good lighting controls allow you to put the right amount of light in the right places.
Dimmer switches reduce light output and energy use. As a practical matter, dimming circuits use incandescent lamps. Halogen lamps can be a good choice, because they are more efficient than other incandescent lamps. Dimmers are available for some full-size and compact fluorescents, too. However, the ballasts and controls are too expensive for most residential applications.
Motion sensors, also known as occupant sensors, are appropriate where people move in and out, but may not stay long. Closets, pantries and bathrooms are examples. Incandescent lamps work well with motion sensors. On the other hand, this kind of use will shorten the life of fluorescent lamps and ballasts.
Even simple on/off switches can help save energy if fixtures are divided into separately switched task areas. For example, the counter, island, range and sink should each have a separate switch. Identify one of these as a night light that will burn throughout the evening. An undercabinet fluorescent near the sink might work well for this.
Three Key Points
Kitchen lighting offers many opportunities for improving efficiency. There are three key points to remember: Design the lighting scheme for best results. Select the appropriate high-efficiency lamps and fixtures. Control the lights properly so they can be used efficiently.
Avoid Perils of Recessed Downlights
Recessed downlights are popular in kitchens because of their relatively unobtrusive appearance. Typical recessed fixtures create a large hole in the ceiling and allow a significant amount of air to pass from the room into the space above ceiling. If this is an insulated ceiling, trouble could be brewing. The first problem is heat loss carried by the air escaping from the kitchen. A second problem is a hitchhiker that goes along for the ride. Water vapor, generated in large amounts in kitchens, flows with the air. By traveling through the recessed fixture, water vapor goes directly into the attic or wall cavity where it can condense on a cool surface, such as the roof sheathing. This could lead to mold, mildew and structural decay. Cathedral ceilings are especially vulnerable to this moisture problem because of their limited ventilation space.
Specify airtight models that have been tested for low air leakage according to ASTM 283E. The results should show no more than 2.0 cfm of air flow at 50 pascals of pressure. Also consider surface-mounted fixtures, such as track lights, instead of recessed ones.
This article appeared in Energy Source Builder #40 August 1995