TODAY'S TECHNOLOGY AND YOU

Energy Efficient Compact Fluorescent Lights

Q: Dear Jim: I went to my home center store to get compact fluorescent bulbs because they save money and may help my children read and study better. How can I determine which are most economical and best for the kids? - Pat F.

A: Dear Pat: You must have been doing your research. Many people know compact fluorescent lights (CFLs) save money, but they are not aware of the other benefits of the high quality light from special CFLs. You will probably want to buy different quality CFLs for various locations in your house. There are many shapes to fit any lamp or lighting fixture.

I have used standard CFLs for years to lower my utility bills, but I recently tested some of the new high-visual-acuity CFLs in my own home/office. I normally have to wear reading glasses to read the telephone book, but I can often read it under these new lights without my glasses.

It is important to understand that the wattage rating of a light bulb measures how much electricity it uses, not the amount of light it produces. A standard incandescent light bulb consumes about 100 watts of electricity to produce the same amout of brightness as a 23 watt CFL. When you count up the number of light bulbs lit in your house at night, using CFLs gives huge savings, which you should notice on your monthly utility bills.

CFLs also last 10 to 12 times longer than incandescent bulbs (10,000 hours of usage compared to only 750 to 1,000 hours). With many standard CFLs priced as low as $7 today, the lower bulb replacement costs is an additional savings. You can purchase long-life incandescent bulbs, but they give off even less light for the amount of electricity they use.

Fluorescent bulbs work by ionizing a small amount of mercury, which produces ultraviolet light (UV) rays inside the bulb. When these UV rays hit a phosphor coating on the inside of the bulb or tube, it produces visible light. By applying different phosphors and combinations of phosphors inside the bulb, the quality and properties of the visible light vary.

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The least expensive CFLs use a single-component halo phosphor. It is inexpensive to make, energy efficient and is acceptable light for hallways, closets and general lighting. These will have a CRI (color rendition index) of about 60 to 70. The CRI rating indicates how true colors look under the light. The sun provides the truest color at CRI 100.

The next level of CFL, which are produced by most of the major lighting manufacturers, uses a more expensive triphosphor coating inside the bulbs. This produces better quality light with a CRI of about 85. These companies also make more expensive CFLs with CRIs in the 95 range, which closely simulate natural daylight. You can find these only at professional electrical supply outlets and custom lighting shops.

The special CFLs that make it easier to read without glare and work with fine detail are often called "full-spectrum" because they simulate the full-spectrum light from the sun. Check for this on the packaging. Their CRI is in the 93 to 96 range, so they also produce natural-looking light.

They are actually much different than the other CRI-95 CFL though. These full-spectrum bulbs produce a higher ratio of scotopic light to photopic light, similar to the sun. Remember, humans have worked and read under artificial lighting for only about 100 years, so our eyes still are more effective (visual acuity) under natural light. Scotopic light is sensed more by the eye's rods (black and white) and photopic light effects the eye's cones.

Lawrence Berkeley Laboratory has done much research on the effects of scotopic light on vision. This causes the pupil of the eye to naturally close down which reduces glare and increases the focusing depth of field similar to a camera lens. This is particularly effective for black and white vision such as reading and study.

When selecting your CFLs at the home center store, look for ones with integral electronic ballasts built into the base. The ballast controls the amount of electric current that flows through the bulb. Electronic ballasts reduce annoying flicker and any buzzing sounds.

If you have the lamp or light fixture on a dimmer switch, make sure to purchase dimmable CFLs. Standard CFLs will not operate if you attempt to dim them. There are also new three-way CFLs, which will fit in any lamp with a three-way socket. For lamps with a large shade, consider using a circular CFL. These have a separate electronic ballast base, which last three times longer than the replaceable bulbs.

Write for (instantly download - www.dulley.com) Utility Bills Update No. 936 - buyer's guide of compact fluorescent bulbs/fixtures (standard and full-spectrum), CRI light quality, ballast types, styles and a room-by-room lighting guide. Please include $3 and a business-size SASE. James Dulley, Illinois Country Living, 6906 Royalgreen Dr., Cincinnati, OH 45244.

James Dulley is a mechanical engineer who writes on a wide variety of energy and utility topics. His column appears in a large number of daily newspapers.

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