Low Energy Bulbs – Understanding Temperature and Wattage Ratings

Most of us were raised on the slightly yellowish, warm light of traditional incandescent light bulbs. About 25% of all electricity used in the United States goes toward lighting our homes and businesses with those bulbs, which is inefficient and expensive. Traditional incandescent bulbs cost 10 to 15 times their original price in electricity over their life-span, which is typically only 1,000 hours or so. A comparable compact fluorescent or CFL bulb will burn five to six years and use 75% less energy while putting out far fewer greenhouse gas emissions. So what's the problem? Many people just don't like the quality of light CFLs emit or they don't know how to interpret the packaging to select bulbs they will like.

Light Bulb Temperature Ratings

All packaging for CFLs carries a reference to the bulb's temperature according to the Kelvin scale. This is a familiar measurement to photographers, but leaves most folks scratching their heads. Here are the numbers you need to remember when shopping for low energy light bulbs:

- 2700 to 3000k: These bulbs will have a tone very like that of traditional incandescent bulbs. The light will be warmer and slightly yellow.

- 3500 to 4100k: Light from these CFLs will be cooler, and whiter. It replicates the "frosted" incandescent bulbs.

- 5000-6500k: Bulbs in this range on the Kelvin scale produce a natural, "daylight" illumination similar to the popular GE "Reveal" bulbs.

GE 8 Pack Energy Smart 60 CFL 13 Watt Bulbs Case Pk 3
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US $59.97

20 GE Proline CFL Bulbs 10W FLE10HT3 2 D Dayloght 6500K
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US $50.00

Wattage Ratings For Light Bulbs

Also bear in mind that the "wattage" rating on CFL packaging is an expression of energy consumed, not amount of light generated. However, since most shoppers think of "brightness" and "wattage" as interchangeable, the packages will compare the output in these terms. For instance, a 13-watt CFL puts out light equivalent to a 60-watt incandescent bulb.

However, the color of the light on the Kelvin scale must be considered in connection with the wattage. A 13-watt CFL that has a low temperature on the Kelvin scale will appear dimmer than an equal bulb with a higher temperature. It is safe to say that CFLs with the most wattage and the highest Kelvin temperature will be the "brightest," although some people may find the quality of their light harsh, and cold.

Lumens - A Measure of Light Output

The actual measurement that expresses the power of light as it is seen by the human eye is a lumen. A 60-watt incandescent, frosted light bulb, for instance, puts out approximately 550 lumens. An understanding of this measurement will become increasingly important as light emitting diodes or LED bulbs become more readily available. Often these products are described by the number of LEDs they contain and the lumens they produce. LED bulbs below 500 lumens are not suitable for anything but task or accent lighting. (Most of these bulbs have not overcome issues in tonal quality and are still too "blue" for general use, although advances are being made rapidly in this area.)

Choosing the right low energy bulbs is more complicated that simply grabbing a 100-watt incandescent off the shelf. However, the quality of CFLs in particular has improved so dramatically in recent years that with just a little homework, consumers can purchase high efficiency bulbs without sacrificing the quality of illumination in their homes and businesses.