Light Bulb Efficiency Update

Here is an informative article on the current state light bulb efficiency. It points out that despite manufacturers claims LED’s are still behind CFLs in efficiency.

Last year Eco Brooklyn put a lot of R&D into LEDs. We build an entire brownstone floor using just LEDs assembled by us. We welded the LED to the circuit board and heat sink and we built our own LED driver. The LED units and circuit boards we got from China, the heat sinks we re-purposed from old computer terminals and the LED drivers were retrofired from car phone chargers.

The end result were lights that put our amazing amounts of light per watt. We definitely created LED that were almost twice as efficient as CFLs. But they process was cumbersome and not translatable to a larger market. The drivers kept failing as well. So we decided that LED technology just wasn’t ready yet, which confirms what is mentioned in this article:

What’s the Most Efficient Light Bulb Today? The Surprising Competition for Efficacy
By Fred Davis

What is the most efficient type of general-purpose light bulb? For perhaps a quarter of a century now, the answer has been clear. Compact fluorescent lamps (CFLs) achieve the highest efficacy, meaning they produce the most lumens per watt, by far, among general-purpose bulbs. In the past few years, despite the facts, a mythology arose that assumed that new light emitting diode (LED) lamps were more efficient than CFLs. But in reality, only in the past eight months have a (very) few LED products arrived to possibly compete with CFLs. The competiton among efficient lamps is suddenly more dynamic than at any time since CFLs first arose.

Over generations using general-purpose incandescent lamps, consumers became accustomed to wattages of 60, 75, and 100 W, the common models that make up 80+% of incandescent lamp sales. The outputs of those “old” incandescents, standardized as 800, 1100, and 1600 lm respectively, are now baselines for competing lamps. Consumers should be choosing bulbs that provide the needed lumen levels while consuming the least watts.

The chart below shows the wattages of the most efficient bulbs available today that meet the minimum light levels in each technology: incandescent, fluorescent and solid-state (LED).

Minimum Light Output

Incandescent Old*

Incandescent (HIR)

Flourescent (CFL)


800 lm 60 W 40 W 13 W 13 W
1100 lm 75 W 50 W 18 W
1600 lm 100 W 70 W 23 W

A number of interesting developments are behind this scorecard, but probably the biggest single news item is that for the first time there is a high-quality LED bulb that challenges the CFL’s status as most efficient. To achieve an 800 lumen output (the old 60W-equivalence), one can now screw in a 13W LED bulb and save as many watts as with a CFL. The best CFLs are still more efficient than LEDs, but this is a huge step for LEDs nevertheless.

This article assesses the recent history and current status of the efficacy contest, across all three technologies: incandescent, CFL and LED.


During the past year, much media and political attention has been focused on the least efficient light bulbs. Unfortunately, much of that has been in the form of misinformation which led people to believe that the banning or demise of general-purpose incandescent bulbs is imminent. This is incorrect. It is true that incandescents of the common wattages (all 60, 75, 100 W models, such as those marked with an asterisk* in the charts above and below) will be phased out, with the 100W the first to depart as of January 1, 2012. But manufacturers are already providing improved incandescent lamps that meet the efficiency levels required by the Energy Independence and Security Act (EISA 2007), signed into law by President George W. Bush.

A century ago, when the tungsten filament replaced the carbon filament, incandescent efficacy shot up from 4 lpw to 12. But since then, efficacy plateaued. The efficacies of the three common-wattage, “old” incandescents are: 1315, and 16 lpw respectively. Even the most efficient non-halogen incandescents are only a bit better; for instance, the best 60W is around 15 lpw.

Starting in the time of the energy crisis of the 1970s, manufacturers began producing “energy-saver” incandescents which produced a little less light and used a little less energy. Later, inert fill gases such as krypton improved efficacy a bit. Line-voltage halogen capsule technology, which has been in use for some years in directional lamps, is now what is inside the least-expensive post-EISA omni-directional incandescents. These lamps, already available, meet the efficacy ranges required by EISA 2007, although just barely. With wattages of 43, 53, and 72 W, they “compare to” the old 60, 75, and 100 watt bulbs, but don’t quite achieve the standardized output targets of 800, 1100, and 1600 lumens. The improvement is incremental but nonetheless significant, since just four years ago it was still not certain that incandescent technology would achieve the efficacies that EISA requires.

The ultimate in incandescent efficiency today is halogen-infrared (HIR) technology, which is incorporated in a few omni-directional models, such as the 40, 60, and 70 watt bulbs shown in the charts. These bring incandescent efficacy up to 2022, and 23 lpw respectively, an impressive improvement over the old incandescents, of perhaps 50%.

Compact fluorescents

The energy crisis of the 1970s nudged
incandescent efficacy, but italso fostered the much more radical energy-saving innovation of compact fluorescent technology. From their inception, CFLs saved a radical two-thirds to three-quarters of the energy used by incandescents; a whopping 250% improvement in efficacy. At first, a few early entrepreneur/tinkerers like Boyd Berends and Asher Zelin worked to marry “small” fluorescent lamps – then just circular fluorescents – with ballasts in order to make workable screw-in adapters. Later, they incorporated the new “twin-tube” push-in compact fluorescents and sleeker adapters. Shapes, sizes, and wattages proliferated to retrofit the variety of existing incandescent sockets, especially in commercial facilities where the increasing cost of electricity easily justified switching to a much more efficient light source.

The first one-piece screw-in compact fluorescent was introduced in the early 1980s. In the late 1990s, the federal government (specifically DOE’s PNNL) made a major push to bulk purchase smaller one-piece CFLs, and the current prevalence of inexpensive spiral CFLs from China is a result of that effort. CFL efficacy has increased, but only incrementally over these decades.  The equivalent to a 60W standard incandescent was 16 or 17 watts in the 1980s, and is now 13W, yielding an efficacy of at least 62 lpw.

Over the same period – thanks in large part to the EnergyStar program – there have been dramatic improvements in CFL size, color, and overall reliability. And prices have declined steadily, totaling an amazing 90-95% reduction, a trend which may finally be changing just in the next month. While the efficacies of the best CFLs are still higher than for the best LEDs, there is not much  further improvement expected from CFL technology at this stage.

Light emitting diodes

Just as the quality and efficacy of CFLs became fairly steady in the past few years, the first LED lighting products finding their way to market have been wildly unreliable. The objective voice reviewing the chaos of early solid state lighting (SSL) has been a DOE program called CALiPER. Here’s a quotation from their July 2009 summary report: “Overall the performance of the … omni-directional lamps tested … is disappointing because none meets the claims published in manufacturer specifications and sales literature. All five products provide less light output than claimed… Unfortunately, buyers cannot rely on manufacturer specifications or equivalency claims when making decisions regarding these products.” And from an April 2011 report:

“Samples of 33 products were purchased anonymously from retail stores and retailers’ web sites between June and August of 2010… most…fail to meet basic performance levels of the incandescent or halogen lamps they appear to replace.”

In some cases of obfuscating claims, “equivalence” to common incandescents turns out literally to be half-true: the LED bulb provides only uni-directional light! Light shining from the bulb in one direction is “equivalent”, but in other directions it is essentially dark.

Misleading and poor-quality products plaguing the LED market in this early period unfortunately obscure the fact that the best manufacturers have been developing high quality products.  The good news is that in the past year, thanks again to EnergyStar and other standard-setting efforts, we can now confidently say that there are a few high-quality, screw-in, general-purpose LED lamps that are also highly efficient.  In November 2010, GE became the first to have an EnergyStar qualified LED light bulb; it is a 40W equivalent that uses eight watts. This June, Philips became the first to have an EnergyStar-qualified LED 60W equivalent; it uses thirteen watts.

It is momentous that there are now LEDs that rival CFLs in efficacy – although the public, and even most practitioners in the lighting and energy conservation fields, are generally unaware.  The most prominent press coverage was probably a June 5 New York Times Magazine article by Andrew Rice, who dramatically reported on the creation of the Philips 60W equivalent:  “Over the past few years, in conditions of strict secrecy, a multi-national team of scientists has been making a mighty effort to change the light bulb.”

The efficiency contest in general-purpose lamps is captured in the following chart showing actual lumens, watts and calculated efficacies for the most efficient lamps today in each technology:

Minimum Incandescent Incandescent Flourescent Solid-state
Light Output (best today)* (HIR) (CFL) (LED)
800 lm 890 lm/ 60W 800 lm / 40W 925 lm / 13W 800 lm / 13W
= 15 lpw = 20 lpw = 71 lpw = 62 lpw
1100 lm 1220 lm / 75W 1100 lm / 50W 1300 lm / 18W __
= 16 lpw = 22 lpw = 72 lpw
1600 lm 1710 lm / 100W 1600 lm / 70W 1650 lm / 23W __
= 17 lpw = 23 lpw = 72 lpw

So, even with the recent significant improvements, incandescence is still the least efficient technology by far. An efficient LED is an exciting development. But the best CFLs are still significantly ahead in efficacy. That is where we stand, but probably not for long.

Price factors

Efficacy, of course, is not the only factor to consider when choosing among light bulbs.  While not all parameters are discussed in this article (see notes), price is an overriding issue at this time. The new high-quality, high-efficiency LED bulbs currently cost in the range of $40 and up. Yes, that is for each light bulb; a huge amount of R&D went into the new technologies inside. The expected lifetime of these LED lamps is long: the rating is 50,000 hours, which, at eight hours of use per day, is seventeen years. But even considering the ultra-long life, the price of one LED is currently some multiples of the CFL price. In any case, we are certainly in the beginning days of this market, when many early adopters are not driven by cost-benefit analysis.

Geopolitics might be introducing another factor into the mix. Just as the first quality LED units are selling at what will presumably be the top of their price range, the price of CFLs is likely ending its long descent and ticking upwards. CFLs (and fluorescents in general) are being hit with a price increase as a result of China’s new price controls of the tight market in rare earth elements. Prices for some of these essential ingredients in lamp phosphors have increased four to ten times in just four months. Actually, rare earths are also ingredients in LEDs, and in many high technology products. Although no one can predict the future, it seems that these price pressures will be relatively modest and unlikely to affect the overall array of competition among lamps.


Government programs have clearly spurred many of these recent efficacy improvements, and are affecting each technology differently. Separate EnergyStar programs exist for CFLs and LEDs, but they thankfully set the same efficacy requirements, keeping the playing field level between the two technologies. The maturity of those two markets is vastly different: virtually all CFLs in the US market today comply with EnergyStar (thousands of models are listed), but virtually no omni-directional screw-in LEDs comply (only three are listed). The incandescent arena is separate and is being driven by EISA regulations, whose efficacy standards do not quite line up with the EnergyStar approach. EnergyStar mandates a certain minimum efficacy for a given wattage range, while EISA mandates a maximum wattage for a given lumen range.

And unfortunately, as new halogens replace old incandescents, consumer confusion is likely to worsen. Right now, for instance, there are many “40W” incandescent lamps, but very few of them are the ultra-efficient 800-lumen HIR models shown in these charts. As the latest CALiPER report (June 2011) put it, “buyers must now learn to understand ratings on halogen and incandescent lamps.”

The field of light bulbs is changing rapidly. As it does, the need for energy policy and conservation programs to be performance-based, instead of technology-based, increases. That is, a specification worded to require “minimum of 800 lumens” makes more sense than “compact fluorescent of 15 watts.” Specifications should also include explicit quality guidelines, by demanding EnergyStar compliance for CFL and LED products. Technologies can then compete fairly against each other on factors such as efficacy, price, and lifetime.

The imminent future

What is coming soon is even more interesting, although this author is cautious about making predictions, especially given the recent excess of hype for LED products. In the next year or so, we may see even more efficacious incandescents, in the range of 30, 40, and 50 watts, bringing efficacies up to 2728, and 32 lpw. Also, it looks likely that a 17W screw-in LED bulb will be available around the beginning of 2012, with a 75 watt equivalency and an efficacy of 65lpw.

But an even more important development in efficient bulbs is also likely on its way: the “L Prize” lamp. The L-Prize is a DOE effort to spur lamp manufacturers to devise a 90 lpw “super bulb” – specifically, a long-life, high color-quality (90 CRI), 900 lumen lamp running at 10 watts or less. A bulb reaching that target would clearly be ahead of anything else currently in the market. Although two others have recently expressed intent, Philips was the first company to enter such an LED bulb, and that was in 2009. That entry has been undergoing extensive evaluation, including in-field testing of 1300 units across the country, as well as lab-testing to verify parameters such as light maintenance and expected lifetime. An announcement is expected shortly, after which the winner is required to produce at least 250,000 units in the first year. The first ones may be available as early as December 2011.

The expected price point of this super lamp? The developers say it will be “significantly higher” than the $40 bulbs that were only recently made available! Interesting times in the efficacy of light bulbs. Stay tuned, and, in the meantime, don’t be myth-LED!

AC/DC the shocking difference

Well before you go hooking wires up to any LEDs you should first know a little about electricity. First of all there are two main forms of electricity in commercial use today.

(All of which are dangerous even if you know what you are doing. So with that in mind do not attempt to play with AC current. All safety precautions should be taken before and during working with electricity. If you are unsure what they are. Do not attempt without a skilled professional.)

These two forms of electricity are:

AC = Alternating Current (ie generator)

DC = Direct Current (ie battery)

LEDs are typically 2-12V DC devices, with a few AC varieties. Household electricity is usually provided in 110-120V AC. This calls for an electronic device to regulate the current into a stable predetermined amount while allowing the voltage to fluctuate in response to an increase or decrease of current sensed by the electronics.

If good design isn’t implemented in this LED ‘driver’ circuit then unnecessary waste through inefficiency can occur. To help with such design issues, National Semiconductor has a design tool for use, try it here.

LED drivers

An LED driver is a self-contained power supply that has outputs matched to the electrical characteristics of your LED or array of LEDs. There are currently no industry standards, so understanding the electrical characteristics of your LED or array is critical in selecting or designing a driver circuit. Drivers should be current-regulated (deliver a consistent current over a range of load voltages). Drivers may also offer dimming by means of pulse width modulation (PWM) circuits. Drivers may have more than one channel for separate control of different LEDs or arrays.
definition from led center

Mean Well's  Cost Effective PLP-60 PCB Type LED Power Supply.
Mean Well’s Cost Effective PLP-60 PCB Type LED Power Supply. A nice built-in design for low cost applications.

LED Drivers should not be looked at as inefficient devices. Here is an example of a press release for a 96% efficiency device.

LEDs without drivers?!?! YES! Acriche™ 4W AC LED from Seoul Semiconductor can be directly plugged into the AC line voltage without a converter or separate power supply. (Watch your fingers!)

So as you can see an LED driver is the type of device that comes in many flavors. It depends on your system wattage needs, for the associated cost increase. In an attempt to recycle reuse and repurpose we, here at EcoBrooklyn, decided in a ‘build it forward’ , commonly associated with a ‘green builder’, attitude, to find some drivers of our own. With some ingenuity and help from our friends (our thanks to you) I undertook the idea of using computer ATX power supplies as a regulated Voltage source. Since an LED is a current driven device any fluctuation in voltage even down to a tenth of a volt can cause a large increase in current flow. This can damage or destroy the LED at worst or cause flickering at best, which can have quite a discomforting effect. So with this in mind and the knowledge that computer electronics are very sensitive to voltage fluctuations on a small but reasonably similar level, I had a great match up. Other standard functions include short circuit, over load, over voltage protections and over temperature shutoff. As well as more than one voltage source in the original package. This we can use to allow more than one type of LED being powered by such VCCS (Voltage controlled current source) supplies.

ATX Power Supply

LED heatsinking

Being a Green Construction company in Brooklyn, NY we like to recycle, reuse and re-purpose materials. Electronics are no exception. This post is about heat sinks. LEDs like to run at about 25 deg C or 70F. Led manufacturers give guidelines for heat sink size and configuration. With this information you can re-purpose a computer processor heat sink. Most PC processors are equipped with a circular heavy duty heat sink. This is usually more than adequate depending on the power of your LED. Another technique for helping cool the LEDs is through an electronic technique called PWM or Pulse Width Modulation. For example, if the LED was to stay on for say 1 sec. (arbitrary) we can electronically switch the led on and off in rapid succession. Persistence of vision will give you the same effect as a moving picture…..a perceived continuation without interruption. This is typically done in a 1000% power for 10% of the time duty cycle. This allows the heat sink to be working on dissipating heat 90% of the time and only absorbing it during the last 10%. With this in mind you can use High power LEDs in tight configurations while not overheating them. Here are some heat sinks I re-purposed for an air cooled lighting demonstration.

From To E-Mail

Lighting with LED 1

Lighting can account for 15-20% of your monthly electric bill. With recent advances in LED technology we are able to reproduce the same level of brightness for 1/5- 1/10th the power. This is a huge savings. If we all work together we can reduce this country’s electrical draw by 10%! That equates to a lot of CO2!

Here is some helpful information from the USgov Department of Energy.


LED light tradeshow

I went to the LED light trade show a couple weeks ago. It was way cool. They are making real progress for residential LED lighting.
One technology that I especially liked was phosphorescent lenses that convert blue LED into visible light like a normal bulb. This varies from normal LED lights that combine the three colors to make white.

The good thing about the phosphorescent lenses is that you can use the cheapest LED which is blue. You also don’t have to worry about getting the color mix accurate since you are only dealing with one color.

The phosphorescent lense looks really cool. It literally starts to glow when you put it near the blue LED.

I think this is going to be a viable solution for greening Brooklyn brownstones. I’m talking with Lightolier and Sony to see if we can put show case lights into the green show house.

Here is the phosphorescent cap and the LED:

LED recessed lighting

Here is an example of the newest recessed LED lighting. There are two shown, one with a wider width than the other. By Juno. It is not cheap, coming in at around $225 US per light. They have heat sinks to keep them cool and each unit has the transformer built in. Why they put a transformer in each one instead of letting people line several lights along one transformer I don’t know.