Measure 9.1.2.1 Substitute Screw-in Fluorescent Lamps for Incandescent Lamps.

Limitations

Screw-in compact fluorescent lamps were designed as replacements for incandescent lamps. However, they cannot be substituted in these common situations:

• fixtures too small for the lamps. The need for a ballast, which is mounted at the screw base, makes the units too fat for many existing fixtures. Also, screw-in units are too long for some fixtures. Some table lamps that use harps to hold the shades may be adapted to accommodate the lamps by using harp extenders.
• need for high light output. The largest compact fluorescent lamps cannot match the light output of the largest incandescent lamps.
• need for dimming. Compact fluorescent lamps should not be used with conventional lighting dimmers. Doing so shortens their life, reduces their efficiency, and may create a fire in the fixture. Osram Sylvania Inc.
• frequent switching. The filaments and starters of fluorescent lamps wear out with frequent on/off switching.
• need for instant light. Most compact fluorescent fixtures have preheat starters, which take a second or two to work. After starting, the lamps require a few seconds to reach full brightness. Lamps that use mercury amalgams (explained below) require almost a minute to reach full brightness.

There are some other, less common situations where you should not use compact fluorescent lamps. These include extremely low temperatures, a need for very good color rendering, sensitivity to acoustical noise, and sensitivity to electrical interference. See "How to Select Compact Fluorescent Lamps," below, for more about these factors.

Energy Saving Potential

The following table compares the energy consumption of ordinary incandescent bulbs to the energy consumption of some typical compact fluorescent lamps that might be used to replace them. The figures indicate a typical saving of about 70%. Few other energy conservation measures offer this much potential for savings.

However, this simple comparison does not tell the whole story. You need to make an energy savings analysis for each potential lamp substitution. For example, much incandescent lighting in commercial facilities is done with downlights and other shrouded fixtures. The lateral light distribution pattern of bare compact fluorescent lamps is inappropriate in such fixtures, so you may have to use fluorescent reflector lamps that are less efficient.

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