Energy Efficient Fluorescent Lamps

Standard fluorescent lamps provide more light per watt input than incandescent lamps. When you choose fluorescents instead of incandescents, you save money; but greater savings can be realized by specifying energy efficient fluorescent lamps.

In response to the need for greater energy efficiency, the lighting industry designed fluorescent lamps that use about 15% less energy than standard fluorescents without a noticeable decrease in light level. For example, a standard 40-Watt fluorescent is replaced by a 32 or 34-Watt fluorescent.

How It Works

To produce light, the standard fluorescent lamp passes an arc of electricity from one end of the lamp to the other. The arc interacts with mercury vapor to produce radiant energy. When this radiant energy strikes the phosphor coating on the inside of the lamp, the phosphor gives off light.

Energy efficient fluorescents operate in the same way but employ more sensitive phosphor. They produce nearly as much light as the standard fluorescent lamp while using less energy.

Finding Energy Efficient Fluorescents

Most lamp manufacturers offer energy efficient fluorescents. GE produces the "Watt Miser", North American Philips offers the "Econo-Watt", and Sylvania make the "Super Saver." The lighting industry also offers energy efficient U-shaped fluorescents. Your lighting supplier will have a current list of lamps available.

Retrofitting With Energy Efficient Fluorescents

Retrofitting fluorescent lighting fixtures with energy efficient fluorescents is simple: remove the old lamp and replace it with the appropriate energy efficient model. Clean the surfaces of the fixture and replace yellowed or hazy lenses when replacing lamps and periodically thereafter to optimize brightness. When you install these new lamps, ask your supplier to make sure they are compatible with the existing ballast. Since energy efficient fluorescents are sensitive to temperature, they should not be used in air handling troffers, drafty areas or in rooms where the temperature might drop below 60° while the lamps are operating.

If fluorescents are used infrequently, it may not be cost effective to install the new energy efficient lamps until the old ones have burned out. However, for areas of greater use, energy costs may justify installing the new lamps immediately.

Energy Efficient Ballasts

A ballast is a necessary part of the fluorescent fixture. Standard fluorescent ballasts use about 14 to 16 watts, while energy efficient ballasts use only 8 to 10 watts. The most efficient type is an electronic ballast. By installing a more energy efficient ballast with energy efficient fluorescents, you'll increase your energy savings. Check for energy efficient ballasts in new fixtures before purchasing.

Why It Pays To Retrofit

Each day that inefficient lamps are used, more money is spent than necessary to operate the facility. By replacing with energy efficient lamps, energy costs will be reduced enough to make up for the investment and monthly operating costs will be lower.

Lamp/Ballast Systems

The chart below compares the energy use and light output of several fluorescent lamp and ballast combinations in a four-lamp, 2'x4' recessed troffer. These are based on manufacturer's information.

ENERGY EFFICIENT FLUORESCENT LAMPS/BALLAST SYSTEMS
 
Ballasts
Lamps
Standard
High Efficiency
Hybrid
(Heater Cutout)
Electronic
(40 Watt)
T-12
Low Efficiency
High Watts

Watts=188
Light=100%
Moderate Efficiency
Moderate Watts

Watts=176
Light=100%
High Efficiency
Low Watts

Watts=144
Light=94%
High Efficiency
Low Watts

Watts=138
Light=99%
(34 Watt)
T-12
Low Efficiency
Moderate Watts

Watts=160
Light=89%
Good Efficiency
Low Watts

Watts=144
Light=90%
High Efficiency
Lowest Watts

Watts=116
Light=83%
High Efficiency
Lowest Watts

Watts=114
Light=89%
(32 Watt)
T-12
Moderate Efficiency
Low Watts

Watts=149
Light=91%
Very Good Efficiency
Very Low Watts

Watts=134
Light=91%
Compatible but
not recommended
Note: recommended

NOTE: Applies to performance in 4-lamp 2X4 recessed prismatic troffers. Light values are based on mean lumens of SP35 lamps.