Buyer's Guide to Energy Efficient Bulbs

* Select bulbs with higher efficacy ratings, which measure the amount of light (lumens) produced per watt of energy used.

* Select the lowest wattage (or highest lumen-per-watt) bulb necessary for the setting in which a light is used.

* Avoid “ long life” bulbs, which have thicker filaments, as they are less energy- efficient.

* Incandescents emit warm light with “excellent” color rendition.

* Easy to find in multiple colors and sizes for a variety of uses.

* Reach full brightness as soon as they are switched on.

* Dimmable.

* Very low upfront costs.

* The least efficient option on the market.

* As a result of their relatively high energy use, incandescents have the highest annual operating cost.

* Must be replaced more frequently than any other option.

* Availability will decline; being phased out in many markets.

* Not recommended.

* May have use in settings where bright lights with excellent color rendition are required on an infrequent basis, such as displaying artwork or closets.

Fluorescent

A much-maligned staple of offices for years, fluorescent bulbs use electricity, a reactive gas, and the bulb’s phosphor coating to produce their light.

They are today increasingly found in residential settings, and compact types (CFLs) are available with both traditional screw-in bases and newer pin-type bases.
 

Lifetime of 4-5 years.

* Choose CFLs with an electronic ballast to increase efficiency and avoid the “buzz” associated with older magnetic-ballast bulbs.

* Read packaging to make sure you select a bulb that can be used with motion sensors, timers, dimmers or 3-way fixtures, or in recessed lighting.

* CFLs come in warm and cool varieties. Choose warm CFLs (2700-3000K, yellowish hues) in general lighting applications. Opt for cooler CFLs (3500-6500K, whiter and bluish hues) for reading and task lighting.

* Get more selection tips in our Q&A "I want energy efficient lighting, but hate the cold light of fluorescents. Can you help?".
 

* Fluorescent lights render colors well, and rapid advances in the technology continue to improve color display.

* Available in a broad range of bulb styles and types, including recessed and dimmable applications.

* Low upfront cost and operating costs make CFLs one of the most economical options for most households.

* Despite improvements, CFLs do not come on instantly, and frequent off-on switching may reduce their lifespan.

* Contain mercury. Must be disposed of properly to avoid environmental and health concerns.

* May not fit in all recessed/can lighting fixtures unless fixtures are designed for high-efficiency lamps (such as CFLs).

* Electronic ballast components add to the embodied energy of CFLs. 

* General purpose and task lighting.

* Living rooms, kitchens, bathrooms, bedrooms, and any other rooms in the home where you’re like to spend more than 15 minutes at a stretch. 

Halogen

Halogen lights are eseentially traditional incandescent lights that contain halogen gas to improve the lamps’s performance.

Lifetime of 1-2 years. 

* Choose more efficient models of halogen lamps, such as the Philips Halogena Energy Saver, GE Edison BT, or Sylvania’s Dalyight Plus.

* ConsumerSearch.com has more selection tips here.

* A (very) slight improvement in efficiency over traditional incandescents.

* Color rendition and light temperature are nearly idential to that of traditional incandescents.

* Reach full brightness as soon as they are switched on.

* Dimmable 

* Use nearly as much energy as incandescent bulbs.

* Short life expectancy on par with that of incandescents.

* Higher upfront costs than incandescents—and, in many cases, than CFLs.

* Not recommended.

* In fixtures wehre high-efficiency lighting may not be used, halogen bulbs may be used as replacements for incandescents to achieve minimal energy savings.

* Closets, where CFLs’ slow-start may be a disadvantage.

* Often found in flood lighting, track lighting, and task-lighting applications. 

LED

LEDs use electricity to stimluate materials that emit light of different colors (except white), and their use in residential applications is relatively new, as the technology is still maturing.

Lifetime of 16-22 years.

* Choose bulbs with 2+ year warranties, as the technology is still developing.

* Look for a 120-degree beam angle or larger, for general lighting. Narrower angles will provide a more spot-focus light.

* LEDs come in warm and cool varieties. Cool LEDs are more efficient than their warm-light counterparts, but choose the lighting color that is right for your needs.

* Read "I'd really like to find an LED light that fits in a GU24 base that I can use in a sconce or an overhead." for tips on using LEDs in recessed lighting.

* Offer substantial energy savings.

* Dimmable varieties available.

* Long lifetime of 16-22 years means buying and changing fewer bulbs

* Contain no mercury or other hazardous chemicals

* Reach full brightness as soon as they are switched on. 

* High upfront costs and little hard data on life expectancy make these something of a gamble.

* LEDs produce very directed light, and despite bulb design to spread their light for general-use applications, may not be well-suited for larger spaces.

* Electronic components add to the embodied energy of LEDs.

* Not yet widely availabile for applications such as recessed and/or track lighting