100-Watt Light Bulb, Goodbye

The 100-watt light bulb is history.

Not yet well-known, except perhaps in California where it has already happened, Thomas Edison’s incandescent bulb is rapidly being phased out.

It’s not because no one wants to use a 100-watt light bulb anymore (many Americans do) nor because there are cheaper alternatives (there aren’t). It’s because the brightest minds in Washington DC decreed it to conserve resources and save the planet – certainly a worthwhile goal, assuming it needed to be saved — while many homeowners look to save on their electric bills by installing more efficient bulbs.

This article is not about bright minds. It’s about available alternatives, which you will need to buy when the 100-watt bulbs in your lamps and overhead fixtures burn out. Some background.

Brightness and power

Consumers think of the brightness of light bulbs in terms of watts. Clearly a 100-watt bulb is brighter than a 75, and each has a role to play in your home. But watts are a measure of the power used by the bulb to give you some light, while how much light it produces is measured in lumens. You can look on the light bulb package to see how many lumens a bulb produces.

A standard incandescent light bulb that uses 100 watts of electricity produces about 1600 lumens of light. Long-life incandescents produce less light, about 1500 lumens — though some produce quite a bit less.

What if a light bulb manufacturer could make a bulb that gave off 1600 lumens of light but used only 75 watts of electricity? Would that be a 75-watt bulb? Well, yes. But less confusing in terms of our bright, new future, it’s a 1600-lumen bulb that will save you 25% on your electric bill.  All good.

The Outlaw

OK, so what is happening to our old 100-watt light bulb? The Federal Energy Independence and Security Act of 2007 requires general purpose incandescent light bulbs to use 25-30% less electricity than today’s. It is effective January 1, 2011 in California and January 1, 2012 everywhere else in the U.S., starting with 100-watt bulbs — then all the rest, down to 40-watt bulbs by January 2014. Bulbs of less than 40 watts and greater than 150 watts are exempt, as are specialty bulbs like appliance lamps, rough service lamps, 3-ways, colored bulbs and plant lights.

A 100-watt bulb that produces 1600 lumens of light has an efficacy of 1600/100 = 16 lumens per watt.  In the second phase of the law, by 2020 all general purpose bulbs must produce 45 lumens per watt of power, with a few exemptions. This is about three times the efficacy of standard incandescents and twice the efficacy of the new halogens.

So incandescent bulbs will still be able to be sold provided they are more efficient than the old ones. Let’s see what our choices are to replace the historic 100-watt incandescent light bulb.

Choices in 1600-lumen bulbs

Note: Price comparisons are based on an informal survey of prices for major brands on the web in January 2011.

Let’s define some terms related to a 100-watt incandescent bulb: Our standard 100-watt incandescent has an A19 pear shape with a medium E26 screw base. It is designed for 120V, with either initial brightness of 1600 lumens and expected life of 750 hours (16 lumens per watt), or initial brightness of 1500 lumens and expected life of 1100 hours (15 lumens per watt). It may be clear or frosted. Its color temperature is a warm-white, about 2700-2800K.


Compact fluorescent lamps are those curlicue bulbs that have been touted as the saviors of the planet. Indeed, fluorescents use less energy (typically 70% less than standard incandescents) and in practice can be expected to last 2-3 times longer than incandescents (not 10 times as suggested by their rated lifetime).

Not everyone likes CFLs, however.  Health hazards are one problem. They are made with small quantities of mercury, which are a health hazard and can contaminate clothing, carpeting and landfills if the bulbs break; they emit small amounts of UV rays (enough to affect some susceptible people); and their flickering may cause migraines. New electronically ballasted CFL’s don’t flicker, though not all migraineurs are convinced, and UV-filtered CFLs are available. A 1992 article published in the American Journal of Epidemiology warns that “fluorescent light exposure remains a potential risk factor for melanoma. “ Am J Epidemiol 1992; 135:749-62.

While early CFLs were cool white, with a bluish cast, they are now available in warm white, though some people still don’t like the quality of light they produce.

CFLs are more expensive, take several minutes to warm up, and most are life-shortened when used with dimmers. Some consumers complain that they don’t last any longer than incandescents. Indeed, switching them off before they have fully warmed up (which takes up to 15 minutes) and regularly cycling them on and off in 5 to 30 minutes like incandescents, will drastically shorten their life — up to 85% — and there is no electricity savings to offset their higher price if they are used in closets, cellars and attics that are seldom lit.

Some CFLs are labeled “instant-on”, which means that the one- or two-second delay or “blinking on” typical of fluorescents before they light has been eliminated.  But they still take several minutes to reach full brightness.

CFL lamp quality is highly variable, especially between one brand and another but also between bulbs. They are inefficient in enclosed spaces where heat builds up, though specially-designed recessed housings are available for reflector-type CFLs (R-CFLs).

Light output declines by 20-30% over their life, meaning that a 1600-lumen CFL becomes an 1120- to 1280-lumen CFL, eating into efficacy (1200 lumens per 25 watts = efficacy of 48 rather than 64). The decline in output is not linear. The highest rate of decline comes early in a CFL’s life.

ENERGY STAR requires a CFL to maintain 90% of its initial lumen rating at 1000 hours and 80% at 3200 hours for an 8000-hour bulb (80% at 4000 hours for a 10,000-hour bulb). So check for ENERGY STAR certification when you buy a CFL.

A 1600-lumen CFL uses 23-30 watts of power, typically lasts 8000 hours (at 20-30% reduced light output), and costs about $2.50 per bulb.


LED light bulbs of good quality are now available as replacements for standard screw-in incandescent light bulbs, but only up to 800 lumens. Some manufacturers label their LED bulbs as “replacements for 100-watt incandescents”, but they exaggerate. A 100-watt incandescent bulb outputs about 1600 lumens of light, and so should its replacement.

LED light bulbs are actually luminaires that contain an array of bright white LEDs. They are highly energy efficient, turn on instantly, don’t use mercury and are more rugged than incandescents and CFLs. But they are not yet suitable for higher-power applications because they generate heat, which reduces their efficacy.

Osram Sylvania’s and Philips’ brightest LED bulbs produce about 800 lumens, equivalent to a 60-watt incandescent, and use 12 watts of power, for an efficacy of about 67 lumens per watt. Rated life is 25,000 hours (but with 30% loss in brightness and a color shift toward blue). They are available at retail outlets for around $40.

If a 1600-lumen LED light bulb becomes available, it may not be suitable for many household applications. LED light bulbs tend to be highly directional. As a result they make excellent PAR reflector-type bulbs (floods and spots) and work well in recessed downlight fixtures and tracks. But LED light bulbs have a light spread of about 140 degrees rather than 360-degrees of incandescents, so they are less useful in table lamps.


Halogen lamps are a type of incandescent. Depending on the shape of the lamp and reflector, a halogen lamp can provide more light for a given amount of power consumption than a standard incandescent. New halogen designs have recently been introduced to replace 100-watt incandescent bulbs, using the thin halogen capsules fitted inside a luminaire. Halogens are dimmable, contain no mercury, and can be manufactured inexpensively, so expect their prices to fall in the future.

Like CFL and LED package labels, halogen labels and advertising can be confusing, sometimes using the phrase “replaces a 100-watt bulb”. This is meaningless. Of course, if you buy the bulb and use it to replace a 100-watt bulb, it will have replaced a 100-watt bulb. That doesn’t mean that it will be as bright.  So check the lumen rating on the package, the measure of brightness. A normal 100-watt incandescent produces about 1600 lumens.

Here are several major-brand screw-in halogen bulbs that you can find online and in stores. All but one specialty bulb produce at least 1490 lumens, the brightness of a typical long-life incandescent. “A19” is the shape of a traditional pear-shaped light bulb.

  • Philips T60 Halogena:  somewhat square-sided; 1600 lumens, 70W, 3000 hr, color 2900K. $6 A good value. See our review of this Philips halogen bulb.
  • Philips 75W A19 EcoVantage: 1500 lumens, 75W, 1250 hr. $3.60
  • Sylvania Soft White Halogen: A19; 1490 lumens, 72W, 1000 hr. $7  This is expensive.
  • GE Edison Halogen 95: A-line; 1490 lumens, 95W, 3000 hr. $3.95  A lower price than the Philips T60, but it uses more power.
  • GE 72-Watt Halogen Clear or Soft White: A19; 1490 lumens, 72W, 1000 hr. $4.63
  • GE 90-Watt Halogen Frosted: TB19 somewhat square-sided, 1580 lumens, 90W, 2000 hr, color 2930K. $4.98.
  • GE Reveal 100-Watt Halogen: A19, 1275 lumens, 100W, 3000 hr, color: 2800K  (neodymium glass). $5.49  This specialty bulb uses 100-watts of power to produce just 80% of normal brightness.
  • Philips B15 Halogena:  decorative bulb B15; 1670 lumens, 100W, 3000 hr, color 2900K. $5.43
  • GE Edison Halogen 100: decorative bulb BT14.5; 1600 lumens, 100W, 3000 hr, soft white. $5.49

ESLs (Trademark of Vu1 Corporation)

While an A19 shape is promised for 2011, it is not yet available. Electron stimulated luminescence lamps use a proprietary technology to emit light by firing electrons at a luminescent phosphor (similar to a CRT monitor or tv screen).

Their light is of similar quality to incandescents, with the advantages that the bulb uses 70% less energy than incandescents while producing 50% less heat, can be made in the shape of a standard A19 light bulb, warms up instantly, doesn’t use mercury, is dimmable, and can last up to 6000 hours.  While promising, the bulbs are not yet commercially available. The bulbs are expected to cost about $20.

Hybrid CFL-halogen

GE announced this bulb as the solution, when it is available, to the slow ramp-up in brightness of a CFL. They created a CFL wrapped around a halogen lamp. Once the CFL warms up, the halogen lamp turns off.

It still contains mercury; turning it off before warm-up still shortens its life. While no price was announced, it would likely cost more than either a CFL or halogen alone, so its cost-savings breakeven time would be longer than a CFL’s.  Will there be a market for it? This is not the lighting breakthrough we have been waiting for.

Stockpiling 100-watt incandescents

Incandescents are inefficient at producing light from electricity. Something like 90% of their output is in the form of heat rather than light. Yet, their color is warm and comfortable for home living. Our fixtures and lamps are designed for them. And in some applications, the heat they produce is a benefit. (It adds to the warming of our homes in winter, relieving the furnace from running quite as much as will be required when we have rid our homes of these bulbs.)

The good news: If you like your current light bulbs, you can keep them — as long as they last. But you will have to buy your lifetime supply before they disappear from supermarket and home-improvement store shelves. (IKEA has already announced that they will no longer sell incandescents.) Thomas Edison’s incandescent light bulb has been used safely for well over 100 years and will be used for many years more by those who stockpile them.

A 1600-lumen incandescent uses 100 watts of power, lasts 750 hours, and costs as little as $.40 – .60 per bulb. Quality is fairly uniform from bulb to bulb. Long-life bulbs are available that will last longer, though they produce only 1500 lumens of light, or less.

What have we learned about our replacement choices?

  • A CFL costs about $2.50 and is rated to use 70-75% less power, so it is the greenest choice. It has several negatives, including its mercury content, unattractive light quality, fall-off in light output, and susceptibility to early burnout due to frequent on-off switching.
  • There are no LED bulbs that produce 1600 lumens yet available (and LEDs may never be able to overcome their heat problem at a reasonable cost). While they will last 25,000 – 50,000 hours, they cost about $40 and because of their directionality and narrow spread are not suitable for many applications. Demand for LED light bulbs will increase when their cost has fallen to a level competitive with halogens.
  • Halogens are available that consume about 30% less power and may last up to 4 times longer than an incandescent. They cost about $6 to achieve this. This is a compromise for those who wish to save some energy but do not like the light quality or mercury content of a CFL or the high cost of a LED light bulb.
  • ESL’s are promising but not yet available. They will cost about $20.
  • Incandescents can be purchased and stockpiled for around $.40 or .50 each or even less by the case. They will burn out after 750 hours, but are ideal in areas that are seldom lit, like closets and cellars that don’t justify the initial expense of another type of bulb because energy savings will be miniscule. They might also be worthwhile to stockpile if you like their light quality better than the alternatives while you wait for a new technology to come along that has the advantages of incandescents while using much less power.

The Federal law that has made us say goodbye to the 100-watt light bulb is based on the notion that legislation rather than making a profit will lead manufacturers to develop more efficient bulbs. Meanwhile consumers have been buying CFL’s to save money on electricity, not recognizing that they may be getting less than they bargained for due to decreased light output and early burnout. See our article on energy-saving replacement bulbs.

Will the bright minds ban cows next?

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