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When designers look at a home's lighting needs, they divide them into three categories. General, or ambient, lighting illuminates space so you can see people and objects comfortably and move about safely. For activities that are visually demanding, such as reading or preparing food, task lighting is best. Accent lighting is used for decorative purposes, usually to highlight art objects or architectural details. The right mixture of these three types of lighting creates an environment where unwanted contrasts, glare, and shadows are eliminated.
With an abundance of new energy-efficient technologies and products on the market, the choices for getting the best lighting design for your dollar have never been better.
Bright Ways to Save
The best source of light is also the least expensive: the sun. By adding windows or skylights to take full advantage of natural light, you can completely change a room's character (see "Daylighting Design"). Keep in mind, though, that too many windows and too much sunlight can cause discomfort and can also run up your energy bills. It's important to balance your use of natural light with your home's heating and cooling efficiency. If you're thinking about adding windows, be sure to read chapter 12.
Another obvious savings technique—which most of us tend to forget at times—is simply to turn off lights when they aren't needed. Installing extra switches in convenient locations often takes care of this problem. Or, in some cases, sensors and timers are the best way to prevent lights from shining needlessly as discussed in "Lighting Controls."
When you do want the lights on, it's possible to cut energy costs by reducing the amount of power required to operate them. Electric power is measured in watts. By using bulbs with lower wattage, your lighting bills will go down. We're not talking about less light here, just more efficient light.
Look for Lumens
Most of us associate the brightness of electric light with the wattage of the familiar incandescent, pear-shaped bulb. You may know, for example, that a standard incandescent 60-watt bulb provides the right level of light in that lamp next to your bed, so that's what you buy every time the bulb burns out. But you will get even greater light output from an 18-watt compact fluorescent. It's the light output you really want—and that is measured in lumens, not watts.
Lighting manufacturers must now label packaging with the number of lumens as well as the number of watts. It may take some adjustment at first, but look for the number of lumens you are getting per watt. Both the 60-watt incandescent and the 18-watt fluorescent give off about 1000 lumens. But the incandescent produces only 15 lumens per watt, while the fluorescent produces over 50 lumens per watt. It's not hard to tell which one is more efficient. A good rule of thumb is to choose a compact fluorescent that is about one-third the wattage of the incandescent you would normally buy.
Don't mistake compact fluorescents for the reduced wattage incandescent "energy savers" that are on store shelves everywhere. These bulbs simply give you less light output. In comparison shopping, look for the lumens you want; then choose the bulb with the lowest wattage.
While the number of lumens tells you how much light you are getting, it tells you nothing about the quality of that light. When it comes to quality, one big concern is color. Natural light is the standard by which all artificial lighting is measured. Colors can look much different in daylight than they do under some electric lights. You've probably discovered this after buying clothing in a store only to find that once outside, the color seemed to change.
There are two numbers that tell us approximately what a light will look like when it's turned on. The color rendering index, or CRI, is measured on a scale of 1 to 100, where 100 represents how colors look in daylight. The higher the number, the more accurately the artificial light will render colors.
The other number measures color temperature. This lets you know whether the light will have more of a reddish (warm) or a blue-white (cool) hue. Color temperature is measured on the Kelvin scale where the "cooler" the light, the higher the temperature (just the opposite of the Fahrenheit scale). Warm lights are below 3,100 K and cool lights are over 4,000 K; 3,500 K is considered neutral.
Standard incandescent lights, like the 60-watt bulb mentioned above, have a CRI of 95+ and a color temperature of 2,700 K. Fluorescent lights vary because the type of phosphor that coats the inside of a fluorescent determines its color characteristics. A typical 18-watt compact fluorescent replacement for that bedside lamp would have a CRI of 82 and a color temperature of 2,700 K.
Light distribution is another measure of quality. This is determined by the shape of the light bulb, any reflective coatings, and the type of fixture. The distribution pattern is important in directing light to the area where it is needed. For example, a ceiling fixture meant to provide ambient lighting to a whole room would be designed to produce a smooth, broad distribution pattern. It would be very different from a fixture used to highlight a painting in the room. Likewise, the light bulbs used in the fixtures should be different: a diffuse, nondirectional bulb would be best for general visibility, and a bulb that casts a directional beam, such as a reflector light, would be more suitable for accenting the art.
When you start looking for new lighting ideas, you may be surprised by all the energy-efficient choices now available and the many advantages these lights offer. Advanced lighting technologies are finding favor over the familiar incandescent bulb—which works pretty much the same way it did when Edison invented it over 100 years ago.
The Edison A-type bulb produces light when electricity heats up a wire filament inside the glass casing. This is how electric heaters work. In fact, more than 90% of the energy produced by these incandescent light bulbs comes out as heat, not light. This explains why they are so inefficient—and so hot. In air-conditioned homes, incandescent lights drive up the electric bill for cooling as well as for lighting.
Hot bulbs are also dangerous. Fires can erupt in closets if exposed lights come in contact with clothes or boxes. In recessed ceiling fixtures, lights can overheat when they are covered by insulation. Perhaps the worst fire hazard has been created by a relatively new type of incandescent light—the popular halogen torchiere, a pole-mounted fixture that shines a bright indirect light toward the ceiling. The 300- or 500-watt bulbs used in these lamps reach operating temperatures of over 1,000°F, easily hot enough to set the curtains on fire. The bulbs that come installed in the bargain-priced torchieres tend to be highly inefficient as well, providing on average 12 lumens per watt—and only 2 lumens per watt when the the lamp is dimmed to one-third of its power. Replacement halogen bulbs are rated somewhat better at 20 to 22 lumens per watt.
Not all halogens have such high wattage, however. Halogens can even save a modest amount of electricity when used to replace a standard incandescent in many common fixtures around the home. They also last approximately three times as long. Halogens are one of the new lighting technologies that have gained widespread appeal, mostly because they produce a crisp white light (color temperature 2,900 K to 3,100 K instead of standard 2,700 K). The popularity of the many styles of halogens proves that lights that look different from the Edison bulb can find a place in today's homes.
The most energy-efficient substitute for the Edison bulb (and for halogens) is fluorescent lighting. Fluorescents use one-quarter to one-third as much energy as incandescents, and they will burn 10 to 15 times longer. Unfortunately, some people believe fluorescents are better suited for warehouses because they still associate them with "yucky" color, slow start-up, flickering, and buzzing. But the new generation of fluorescents, developed specifically for use in the home, has virtually eliminated those annoying qualities. Now you will find an assortment of fluorescents that cast a warm glow and render colors very accurately. Fluorescents also produce light without getting too hot. There's even a new fluorescent replacement for those halogen torchieres. It supplies more light, uses one-fourth as much energy, and is not a fire hazard.
All fluorescent lights need a ballast to operate. The flicker and buzz occur only in models that use magnetic instead of the newer electronic ballasts. Magnetic ballasts are also less efficient and bulkier. There are several good reasons, then, to choose fluorescents with electronic ballasts, even though the magnetic models are less expensive.
In lighting fixtures specifically designed for fluorescent bulbs, the ballast is contained in the housing of the fixture. The fluorescent bulb or tube used in the fixture will have a pin base—rather than a standard screw base—that fits into the ballast. Ballasts long outlast bulbs, so you can replace the bulb several times before you need to replace the ballast.
Compact fluorescent lights come in both pin-base and screw-base models. When you are putting in new lighting fixtures, by far the best choice is to install compact fluorescent fixtures complete with ballasts. The pin-base bulbs used with them cost less than screw-base bulbs and will always be the perfect fit.
A screw-based compact fluorescent fits directly into a standard socket. This means the ballast is contained in the base of the bulb, making it wider and heavier than the base of a standard incandescent bulb. These integral bulbs come in a wide choice of sizes and styles, but they are more expensive than pin-based bulbs because they are both ballast and bulb.
Another screw-in option is a modular compact fluorescent. These have a ballast that screws into a standard socket. Pin-based compact fluorescent bulbs are inserted into the ballast. The modular compacts offer the advantage of using the ballast for its full lifetime and the less expensive pin-based bulbs as replacements.
Where to Shop
As energy-efficient lights become more popular, they can be found in more consumer outlets. Most large home improvement centers carry a good selection of straight fluorescent tubes and compact fluorescents. Generally, if a local hardware or grocery store carries any on their shelves, the selection is limited.
To get a wider selection, check the Yellow Pages for lighting stores, and for building and electrical suppliers. You will probably get the broadest range of energy-efficient bulbs and fixtures by mail from catalog companies, but expect to pay a little more. Some utilities offer rebates on lights or fixtures, and others lease compact fluorescents to customers.
Excerpted with permission from No-Regrets Remodeling by Home Energy (1997)