Types of Lighting

Incandescent Lighting | Compact Fluorescent Lamps | LEDs | Linear Fluorescent Lighting | HID Lighting

Incandescent Lighting

Most lighting found in homes today is incandescent lighting. In an incandescent lamp, electric current heats up a metal filament in the light bulb, making it glow white-hot and give off light. The problem is that only 10% to 25% of that electricity is actually used to produce light — the rest ends up as heat. During the winter months, incandescent lighting is an expensive form of electric heat; during the summer months, it makes your air conditioner work harder than it has to.

Recent federal light bulb standards were phased in from 2012 to 2014 (and 2011 to 2013 in California) requiring incandescent lamps to use less energy to produce light equivalent to conventional 40-, 60-, 75- and 100-watt bulbs. In response to the standards, manufacturers have introduced new incandescent bulbs—technically halogen-IR bulbs— that look and perform just like traditional incandscents but use about 30% less energy.

While these new halogen incandescent lamps save energy relative to traditional incandscents, they still use three times more energy than compact fluorescents and LEDs. We strongly recommend replacement of incandescent bulbs with these high-efficiency alternatives. The energy, environmental, and economic benefits of these technologies are discussed in detail below.

Halogen bulbs are really a specialized type of incandescent lamp. A variety of halogen lamp types is available. Halogen is often used where high light quality or precise light focusing is required. Many halogen lamps feature a parabolic aluminized reflector (PAR) to improve light focus. Other small halogen MR-16 lamps are common in track lighting or accent lighting to highlight artwork or architectural features. While halogen lamps are slightly more energy-efficient than standard incandescent lamps, they cannot come close to the energy efficiency of CFLs or LEDs. The range of efficient alternatives for reflector and other specialty lamps continues to grow, as discussed below.

Compact Fluorescent Lamps

The introduction of compact fluorescent lamps (CFLs) in the early 1980s revolutionized lighting but only in the past decade have they gained mainstream popularity. Improved light quality, greater product variety, lower cost, and aggressive marketing and promotion among energy agencies, utilities, lawmakers, environmental groups, and even major retailers have really helped boost the market for CFLs. Still, some consumers remain skeptical. So, what is the deal with these light bulbs? Do they offer the same light quality? Are they safe for your home?

Compact fluorescent lights last on average ten times as long as incandescent lights.

CFLs are getting so much attention for the simple reason that they use just one-quarter to one-third as much electricity and last up to ten times longer than incandescent bulbs, while providing the same level of light. This high performance means they waste much less electricity in the form of heat.

Common CFL Myths

  • The light is green. CFLs are not like incandescent bulbs; they do not emit full-spectrum white light. Instead, the color must be manufactured, which can yield different results from product to product. ENERGY STAR-qualified warm white and soft white CFLs closely approximate the light of a typical incandescent bulb.
  • Don’t they flicker? Today’s CFLs use electronic ballasts that eliminate the flicker common to older CFLs and linear fluorescent systems using magnetic ballasts.
  • CFLs aren’t bright enough. An incandescent bulb of a higher wattage (say 100W) has a slightly higher, “bluer” apparent color temperature. If you think your CFL is too dim no matter what wattage you try, try a higher color temperature instead.
  • It is best to leave CFLs on all the time. Turning CFLs on for very short periods can reduce lamp life. You will maximize CFL lifetime and performance by leaving them on for 15 minutes or longer.

You can find CFLs in styles to replace virtually any incandescent you currently use: traditional glass-encased bulbs, globe-shaped vanity bulbs, and flame-shaped bulbs with smaller screw bases for your candelabras and sconces. The majority of CFLs sold today are spiral CFLs, which are the exact dimensions of an incandescent bulb so they will fit into most existing lamp fixtures. You can also buy three-way CFLs, dimmable CFLs, and bulbs adequate for use in low temperatures and moisture (but be sure to check the label).

CFLs, Mercury, and Safety. Compact fluorescent lamps contain a small amount of mercury that is needed to produce light (less than 5 mg). The amount is small enough—about the size of the period at the end of this sentence—that it presents very little danger during household use.

However, lamps should be disposed of properly to minimize the spread of mercury in your home or in landfills. A number of large, retailers, and local communities have established recycling programs for spent compact fluorescent lamps.


Light-emitting diodes (LEDs) (also called solid state lighting, SSL) technology is evolving rapidly as a new high-efficiency option for a variety of residential lighting applications. An LED is a pea-sized device that uses semi-conducting metal alloys to convert electricity into light. These diodes can be arranged in matrices or clusters offering great design flexibility. Over the past few decades, the development of first blue and now white LEDs has extended their use from simple indicator lights to a wider range of display, task and general lighting applications. 

A rapidly expanding variety of white LED products are on the market for home use today, including replacement bulbs for many fixture types as well as LED downlight fixtures (recessed cans), desk lamps, under-cabinet lights, outdoor pathway lights, and decorative string lights. Most of these products have reached the market only within the past 5 years.

So should you rush out and buy an LED lamp? That depends. Because white LEDs are still relatively new for general applications, performance varies from product to product. For some applications, products are still very expensive, although prices are dropping rapidly. The best white LEDs are 30% more efficient than CFLs, but for other products, CFL and LED efficiency is similar. You may want to start out by trying a few LED replacement bulbs. When renovating, look for integrated LED fixture options, particularly for recessed cans and under-cabinet lighting.

Look to ENERGY STAR and the DOE Solid-State Lighting Program for updates on product performance, availability, efficiency, and costs.

Linear Fluorescent Lighting

When you think of standard tube fluorescent lighting, you may get an image of the buzzing, flickering bluish-white lights in supermarkets or older offices that make colors look washed out and give some employees headaches. That is hardly the kind of light you want in your house. Well, times have changed. Linear (tube) fluorescent lighting has improved dramatically over the past 20 years. The best lamps with electronic ballasts are a far cry from what most of us think of as fluorescent lighting. They now make sense in places other than your garage or basement workshop. In fact, they can provide very satisfactory (and energy-efficient) recessed lighting around the perimeter of a living room, or overhead lighting in kitchens and bathrooms. You can now even buy dimming fluorescent fixtures to vary ambient light levels precisely for excellent mood lighting. Most fixtures are now sold with electronic ballasts, a must for use in living areas. Going with electronic ballasts will save energy and eliminate any noticeable hum or flicker, making them far more pleasant in your home environment.

Linear fluorescent fixture showing cutaway lamps and ballast. You can buy quiet, flicker-free electronic ballasts for these fixtures.

When shopping for linear fluorescent lighting fixtures and lamps, it helps to know what you want. Even at retail lighting stores, salespeople may not be familiar with some of the advanced products on the market. If you can’t find what you want, go to a commercial lighting supplier. Commercial-grade fluorescents offer higher quality and greater selection.

When selecting linear fluorescent lighting, look for products with a high color rendering index (CRI), that is, 75–90 CRI, or the higher the better. CRI is a measure of the ability of the light to illuminate colors accurately. Also, look for high efficiency (or efficacy, as it is called in the lighting industry). Lighting efficacy is measured in lumens (light output) per watt (electricity use). The best fluorescent lamps use special coatings (trichromatic phosphors) to achieve both high CRI ratings and high efficacy. The most energy-conserving fluorescent lamps are thinner in diameter (T8 and T5). New standards have eliminated all but a few specialty T12 lamps. If you have existing fixtures with larger diameter T12 lamps, you will need to replace the ballast and upgrade to T8 lamps. It may make sense to go ahead and upgrade to a more efficient fixture designed for T8 or T5 bulbs. Despite the initial cost of replacing the ballast and/or fixture, you should realize a payback through substantial energy savings, not to mention much better-quality lighting.

HID Lighting

High-intensity discharge (HID) lighting is what you typically see along streets and in parking lots. HID lighting has advanced almost as quickly as fluorescent lighting in recent years. There are three types commonly used: mercury vapor, high-pressure sodium, and metal halide. Like fluorescent lamps, they require ballasts to operate, and most HID lamps take several minutes to warm up. The primary household use of HID lighting is outdoors: to light up the driveway, swimming pool, tennis court, etc.

While mercury vapor lamps are still found in some outdoor fixtures, they are quickly becoming obsolete because of the higher efficacy of high-pressure sodium and metal halide. High-pressure sodium lamps are available with efficacies as high as 140 lumens per watt, though the light is somewhat yellowish. Metal halide lights produce a whiter light, closer to incandescent in quality, with relatively high efficacy.