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LED Revolution

July 5, 2013

The most important innovation in energy efficiency over the past ten years has been LED lighting1.

LEDs achieve an 85% improvement in efficiency, when compared with a 100 watt incandescent bulb: Or 40% when compared with a comparable compact fluorescent lamp (CFL).

CFLs were forced on Americans by Congress2, while LEDs are a free market success story. The recent, rapid advances in LEDs are making CFLs a bad choice.

The cost of LED lamps is dropping rapidly, and their life is far better than CFLs or incandescent bulbs.

LEDs last for 15 years3, or more, when used 4 hours per day, and can save homeowners a lot of money.

An LED replacement for a 100 watt incandescent bulb can save around $12.50 per year in electricity costs, and recover the investment in a $12 LED in around 11 months4. Not only are there savings from using less electricity, there is the additional savings from not having to buy new CFLs, or incandescent bulbs.

LEDs to replace 100 watt bulbs are still in short supply, but there is an ample supply of LED replacements for 75 watt and 60 watt incandescent bulbs. Dimmable lamps may cost more.

Replica of 1879 Edison bulb used by GE at its 100th anniversary, alongside a modern LED lamp.

Replica of 1879 Edison bulb used by GE at its 100th anniversary, alongside a modern LED lamp.

While prices vary widely with many various shapes and types, Table 1 provides some sense about the various alternatives.(Not dimmable)8,0009502700K$6.50LED replacement for 75 watt bulb

 

Table 1

Flood Lamp

Life in Hours

Lumens

Color Temp

Price

60 Watt Incandescent 1,700 360 2850K $10
CFL comparable Lamp(Not dimmable) 8,000 950 2700K $6.50
LED replacement for 75 watt bulb(Not dimmable) 50,000 970 3000K $40
In this example, a $40 LED Flood Lamp can avoid the purchase of 6, CFL Flood Lamps, at a savings of $39. Savings of $290 would be realized by avoiding the purchase of 29 lamps, when comparing the LED with the Incandescent Flood Lamp.

Table 1, establishes that expensive LED R40 and R30 flood lamps, used in kitchens and family rooms for area lighting, save money over the life of the lamp. Their pay back from using less electricity is around three years, which, when added to not having to buy CFLs or Incandescent bulbs over the life of the LED lamps, makes a compelling case for buying LEDs.

Table 2 compares a replacement for a standard 60 watt A16 bulb.

Table 2

Standard A16 Bulb

Life in Hours

Lumens

Color Temp

Price

60 Watt Incandescent 1,000 850 2850K $0.40
LED replacement for 60 watt bulb(Dimmable) 25,000 650 3000K $13
In this instance, using the LED will avoid the purchase of 25 incandescent bulbs over the life of the LED, which saves $10. It will, however, require 21 months of electricity savings to recover the initial cost.

The cost of LEDs is falling rapidly, so $8 LED replacements for 100 watt bulbs should be available within a few years.

Flood lamps are frequently used where ceilings are 20 feet high, so there is the added benefit of avoiding the use of a tall ladder with the potential for an accident.

Even street lighting applications can save communities money, where the high cost of labor to change out a lamp justifies the more expensive LED lamps.

However, LEDs don’t make sense where light bulbs are only used a few minutes each day, such as in a closet.

The frugal home owner will replace bulbs used 4 or more hours per day with LED lamps, and use the old incandescent bulb in the closet, or wherever usage is low.

It’s important to determine the Lumen rating for an LED lamp, and then compare this with the Lumen rating of a comparable incandescent bulb. The rating for a 100 watt bulb, for example, is around 1600 Lumens.

Comparing Lumens is the best way to ensure that the LED lamp can provide the same amount of light as the incandescent bulb it’s replacing.

The other important rating is color temperature. Ignore any CRI Index and use the color temperature, in degrees Kelvin. Any temperature below 2700K will provide poor light rendering. Daylight is 5000K, while 3000K provides acceptable color rendering for most people5.

Parents, for good reason, used to tell their children to read where the lighting was good.

Industrial and commercial lighting installations are designed to provide the amount of light required to perform tasks efficiently and safely, and these same rules apply to homes.

Standards have been established for light levels on surfaces for different applications.

Machine tool surfaces require 100-foot candles as do desk tops in schools. Reading also requires 100-foot candles on surfaces. Some precision applications require much higher levels of lighting, while a parking lot floor requires only 15-foot candles.

The Illuminating Engineering Society has published tables showing recommended light levels for various tasks.

Reducing the recommended light levels can impede productivity and learning, and threaten safety.

Conclusions

When determining what lighting source to use, it’s probably best to skip CFLs altogether, and go directly to LEDs. CFLs contain mercury which is likely to accumulate in landfills, so Congress did us no favors when it outlawed incandescent bulbs and tried to foist CFLs on Americans in an attempt to cut CO2 emissions.

As a rule of thumb, incandescent bulbs used less than 2 hours per day throughout the year, should not be replaced; unless there are other considerations, such as safety.

Lower cost LEDs should be available in a few years which will make the economic argument for replacing incandescent bulbs with LEDs more compelling.

LEDs, like fracking, are another triumph of private enterprise and free markets … not government.

Notes:

  1. LEDs  that emit red, orange and green light have been available for the past dozen years, but it’s only been in the last few years that LEDs capable of emitting white light have been developed.
  2. Energy Independence and Security Act of 2007 (EISA) designed to reduce energy use and CO2 emissions.
  3. While LEDs don’t typically fail, they degrade and emit less light over time. Life is typically determined by when light output is reduced 30%. Testing, from which projections of life are made, can take several months, which delays certification by industry organizations or the government.
  4. Savings are based on 4 hours daily usage, and electricity costs of 11 cents /kWh.
  5. Color rendering is subjective, and its perception differs between people.

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