Best Uses of CFLs in the Home

by. Eric Strandberg. LC, Lighting Design Lab

When you look for ways to lower your home lighting costs a good place to start is by using fluorescent lighting in place of incandescent. Fluorescent lights use far less energy to produce the same amount of light (lumens) than incandescent sources, produce less heat and last many times longer.

Compared to the old fluorescent lamps, the new ones have vastly improved performance qualities.
Better color
Lower cost
Smaller size
More reliable

You can convert to fluorescent lighting by either replacing the existing incandescent light fixtures, or retrofitting existing ones with Compact Fluorescent Lamps (CFLs). Replacing the fixtures with dedicated fluorescents (fixtures designed only for fluorescent) is generally the best option, but this is not always possible. The other choice is using a screw-in CFL to retrofit the old fixture. These "medium-base" CFLs have the ballast attached to the base of the lamp.

One of the challenges in making conversions with CFL retrofits is maintaining consistent light levels before and after conversion. Incandescent lamps produce 5 to 20 lumens per watt and CFLs produce 20 to 80 lumens per watt. A good rule of thumb is to multiply the fluorescent wattage by 3 or 4 to find an equivalent incandescent wattage (e.g., 15W CFL = 45 to 60W incandescent).If you have a dimmer switch on the circuit be aware that fluorescent lamps need special dimmers and dimmable ballasts. There are a few companies that make screw-in CFLs that operate on standard dimmers, and the packaging is clearly marked stating this .Also, be aware that at the end of 10,000 hours, the CFL will have lost up to 30% of the original light. This is called lumen depreciation. Another area of concern is size and shape. CFLs are often longer and wider (particularly at the base) than incandescent lamps and you may need to use socket or harp extenders, or change lenses and shades on the luminaire.

The clearest way to lower home lighting energy use is to target fixtures that are on for long periods of time (3 hours or more). Kitchens, work shops, laundries, recreation rooms and home offices are spaces where fluorescent may make sense. These areas can use either large lamp fixtures, ideally with T-8 lamps and electronic ballasts, (see article "I Hate Fluorescent") or CFL fixtures. Exterior lights or table lamps often burn for long periods, and for these CFLs make sensible retrofits. Also, fixtures that are difficult to get to are good candidates for conversion because of fluorescents long life. Putting fluorescents in less used spaces, or where the lights are turned on and off frequently, like a pantry, garage or walk-in closet may not be cost-effective solutions.

Simple calculation of the annual cost of home lighting (NW $ Averages):
Annual energy cost = (W x H) x 365/1000 x $.05*W = watts, H = hours used per day
Annual lamp cost = (H x 365) /RLL x LCH = hours used per day, LC = lamp cost, RLL = rated lamp life
*$.05 is an average, use your actual electric rate

source: http://www.elflist.com
image: www.dbtechno.com