![]() |
|
Besides energy savings benefits fostered by the legislation, the consumer now has many more options on the type of lamps available to develop the lighting scheme that meets their functional needs and desired aesthetic appearance. To help with the selection, lamps are labeled with information that will help locate the right combination of function and appearance. Color temperature and color rendering index (CRI) are the primary factors used to quantify light quality. Color temperature or chromacity refers to the color appearance that comes from the light itself. It’s what can create the right "mood". Color temperature is measured in degrees Kelvin and indicates the visual "warmth or coolness" of the light given off by the bulb itself. Color temperatures for residential bulbs range from a "warm" red-yellow appearance (starting at 2000o K), to a "neutral" white (at 3500o K) to a "cool" white-blue starting at about 4100o K. The common "cool white" shop light gave off the typical bluish color giving the surfaces illuminated a harsh and distorted appearance. Incandescence, at about 2700oK for the standard residential bulb, are naturally warmer and give a more natural appearance to people and objects. In general, warm light sources should be used at low lighting levels, cool sources at high levels. Color rendering, or CRI, is the ability of a light source to represent colors in objects. It is a relative measurement of how natural or distorted an object appears when illuminated by a particular bulb. CRI is expressed on a scale of 0 - 100; the closer the rating is to 100, the more natural the appearance of the illuminated person or object. Most incandescent have CRIs close to 100. But fluorescents generally range from 40 to 90. For comparison purposes, the old standard cool white fluorescent had a ranking in the low 60s. A ranking in the 70s is considered the lowest acceptable range for general residential purposes. Above 80 is said to be "high quality" lighting, Most of the major improvements in lighting in recent years have been in fluorescent technology. Because fluorescents produce more lighting at a lower cost (lumens per watt) than incandescent, the new energy reduction requirements spurred the development of new lamps that operate at reduced watts and in many cases could be used as a direct substitute for incandescent in existing fixtures or for new lighting situations that only incandescent could solve in the past. Previously, the fluorescents were popular only in office or work settings, primarily because of the type fixture required but also because of the quality of the lighting they provided. Now, fluorescents can fit almost any lighting or mood setting desired. The powdery phosphor coatings used on the inside of the bulb in the older style fluorescents have been replaced by more expensive "rare earth phosphor" that produce a more efficient and visually appealing light. Different blends of rare earth and conventional phosphors can be used to develop a range of lighting levels and quality for a variety of purposes. These bulbs can be used in many fixtures previously only usable with the relatively inefficient incandescent. READING THE LABELS For example, a standard 60-watt bulb might be listed to produce 800 lumens for 1000 hours. Using this bulb for four hours each day would cost $8.76 per year at .10 per kilowatt-hour. As an alternate, a compact 15-watt fluorescent with greater light output and life (900 lumens and 10,000 hours respectively) would cost only $2.19 a year to operate. Thus, using a fluorescent bulb would save you over $6.00 annually. In addition, the fluorescent bulb would last six years compared to only eight months for the incandescent. Over a six-year period, just the savings from reduced energy usage should make up the difference in the initial bulb cost. Also, giving consideration to the fact that you wouldn't have to buy any bulbs in that period only increases the savings. WHAT DOES THE GREEN LIGHT LABEL MEAN? |