Energy Efficiency E-Library > Lighting > Compact Fluorescent Light Bulbs

All about compact fluorescent lighting

As you make the decision to get Power Smart, your first step in saving energy is often switching out electricity-hogging incandescent bulbs for compact fluorescent bulbs. Choosing the right light, however, can be a daunting task for the unenlightened.

Before you head to the hardware or lighting store, take the time to educate yourself about compact fluorescents, in particular the basics of colour temperature, shape and lumens (light output). Keep in mind that not all stores have a wide selection of CFLs, and that a phone call in advance of your trip may save you some time.

Always look for the ENERGY STAR® label, which identifies products that have been tested to meet operating, reliability and energy efficiency criteria.

Not your grade school fluorescent

Today's compact fluorescent light manufacturers offer a wide variety of CFLs that deliver on light quality and convenience as well as energy savings – usually about 75 per cent better than incandescents.

And if you've heard someone complain of a CFL that delivered a light too yellow, too dim or even too bright for comfortable reading, consider this. A 2007 test by Popular Mechanics Magazine that used technical measures as well as the subjective ratings of testers discovered that six of seven CFLs tested against an equivalent incandescent scored higher for reading – and all seven CFLs scored a higher overall grade.

The cost of CFLs

Yes, CFLs are more expensive than incandescents, but replacing a 100-watt incandescent with a 25-watt CFL, for example, will save approximately $30 in electricity over the life of the CFL.

Remember, too, that CFLs last about eight times as long as incandescents – expect to replace them only every five to six years. Given that long life, it's even more important to choose the right light – the one that best suits the situation – for a given room, as that's the bulb you'll be living with for quite awhile.

CFLs and mercury content

Compact fluorescent bulbs do include small amounts of mercury, a toxic metal that can lead to adverse health effects for fish and humans. But with amounts of less than 4 mg of mercury per bulb – about one-fifth that found in the average watch battery and less than 100th found in your typical amalgam dental filling – and convenient access to CFL recycling facilities, the threat is not considered significant.

Some manufacturers, including Philips with its 'Alto' CFLs, offer even lower amounts of mercury in the bulbs.

Three steps to choosing the right CFL

Armed with basic knowledge about colour temperature, bulb shape and lumens, you'll be equipped to make the right choice.

Colour temperature

Many stores have only basic information about colour temperature, a feature that's sometimes a challenge for first-time CFL buyers. Know what to look for, and you'll get the right light.

Colour temperature refers to the shade of white light, identified by correlated colour temperature (CCT) and measured by Kelvin (K). Warmer colours correspond to lower Kelvin numbers, while higher Kelvin numbers indicate a cooler, bluer light.

The majority of CFLs on the market are 2700-3000 K and project soft white or "warm" light. These bulbs enhance warm colours (red, yellow and orange) found in the home.

Bulbs with a slightly higher K rating (up to 3500 K) can be optimal for reading, but as that K rating increases (to 4100, 5000 and 6500K) the effect is increasingly white to bluish light that enhances cooler colours (blue, green, violet). The higher K-rated lights are often referred to as "daylight".

You may also see some bulbs labelled by a CRI (colour rendition index), which indicates how true colours appear under a light. Bulbs with a CRI rating of 60 to 80 are suitable for offices, classrooms and supermarkets, but all Energy Star rated CFLs have a CRI rating of at least 80 and are better for home, retail, restaurant and lobby use.

Bulb shape

Different fixtures require different types of bulbs, and compact fluorescent bulbs come in a variety of shapes and sizes. Check out our CFL fact sheet [PDF, 1.0 Mb] to find the type of fixture you'd like to equip with a CFL, and then decide which CFL works best for you.

Choosing the Right Lighting Level

Look for CFLs that produce the same amount of light (measured in lumens) as the bulb you are replacing. Typically, the following conversions will apply:

* This is an approximate replacement guide only – light output (measured in lumens) will vary with make and model of bulb chosen. Look for the ENERGY STAR logo for an assurance of an accurate equivalency guide.

Where do CFLs work best?

Frequent on and off switching can shorten a CFL's life. To take full advantage of the energy savings and long life of ENERGY STAR qualified CFLs, it's best to use them in light fixtures you use the most and are on for at least 15 minutes at a time. This is not to say you should leave lights on all day.

Good locations for CFLs include:

• family and recreational rooms
• living rooms
• kitchens
• bedrooms
• hallways
• front porches (if you use a CFL outside, check the lamp's packaging for the minimum temperature required for starting)

Because CFLs have a long product life, use CFLs in hard-to-reach places so that they don't have to be replaced as often.

• ceiling pot lights
• accent lighting
• chandelier fixtures

Dimmers and three-way lights

Some CFLs are specially designed to work with dimmers and three-way switches (tri-lights). Check the package to make sure the light is suitable to the specific use.

Screw-in Replacements

Fluorescent lamps with incandescent-type screw-in bases or adapters will fit into many incandescent fixtures. Several types are available. The "twin-tube" or Biax lamps come in 5 to 32 watt sizes and plug into reusable screw-in ballast/adapters. These ballasts have a rated life of 45,000 to 50,000 hours. Direct-wire adapters also are available.

Some compact fluorescent lamps come as a complete lamp/ballast unit. When the lamps burn out, the ballast must also be replaced. However, these lamps will last about 7 to 10 times as long as standard incandescent lamps and are available in 15- to 28-Watt sizes. They are typically used to replace 60-watt to 100-watt incandescent lamps.

Circline lamps are fluorescent tubes formed into a circle and designed as direct replacements for incandescents. Some models have ballasts built into the lamp base; others come with two circular tubes – one within the other – offering a wider selection of wattages. A 27-watt circline lamp provides the same amount of light as a 150-watt incandescent, for one-fifth the energy cost.

The following table shows a few typical incandescent lamps and the appropriate fluorescent replacements.

Fluorescent Facts

• Screw-in fluorescents, which are somewhat larger than incandescents, come in a variety of sizes and shapes including globe, tube, and circle styles.
• Today's compact fluorescents have much-improved colour rendition and a "warmer" light than standard fluorescents.
• Some fluorescents are heavier than traditional bulbs because they require a ballast.
• Measure a fixture before buying compact fluorescent bulbs. Fluorescents are larger and don't always fit traditional fixtures. Harp adapters can often remedy this problem.
• Most fluorescent lamps cannot be dimmed and are not recommended for enclosed fixtures. Fluorescents also require a special ballast for operation in outdoor settings because of sensitivity to low temperatures.
• Many fixture manufacturers are now making fixtures especially for these high-efficiency lamps. When buying new lighting fixtures, ask for ones designed to accept compact fluorescents.

Tungsten Halogen Lamps

Tungsten halogen (or quartz) lamps are more efficient, provide longer life and give a whiter light than standard incandescent bulbs. Depending on the application, energy savings can be significant. Halogens are suitable in applications like track or spot lighting, where they are often dimmed, and for use with motion sensors (for example, outdoor security/convenience lights), where they frequently cycle on and off. Halogen lamps typically last twice as long as standard incandescent lamps.

We encourage customers to get rid of their old halogen torchieres for a number of reasons. Firstly, the lamps are inefficient in their delivery of light, relying on the ceiling to reflect light back to where it is needed. Secondly, torchiere lamps typically use 300-watt bulbs which can become a fire hazard because of the extremely high temperatures they reach. Consequently, the CFL torchiere is a very good substitute.

A recent development in halogen technology is the halogen infrared (HIR) lamp. HIR technology focuses much of the lamp's heat onto the filament, resulting in more light output and significantly less waste heat for the same energy use. A 55-watt HIR lamp will provide the same light output as a 90-watt standard halogen lamp.

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