Change Your Bulbs Every 27 Years!

By Jeffery M. Wolf, General Contractor, St. Petersburg, Florida

In 2009, I built a super energy efficient house that received one of the best energy ratings in the country. That home received a minus 9 HERS (Home Energy Rating) Score. Among other energy saving systems, we used all LED lighting inside and out. As a custom home builder focused on sustainable "Green" construction practices, I have followed the development of energy efficient lighting for over twenty years. It seems that LED lights are improving at a rate similar to computers, with a new generation every year or two. I have watched the technology grow from a limited choice of expensive fixtures to a large selection of moderately priced fixtures with excellent lighting performance. Our first all-LED project was finished in 2007. Those lights used so little power that we had to adjust the home dimming system so that it would operate them -- the load was too small for the system to recognize. Those lamps are still in operation today. Current systems are now designed to operate with LED lighting.

The two places where LED lights shine (pun intended), are recessed can lights and under-counter strip lights. The current crop of LED recessed can lamps puts out excellent light, using only 12 watts or less of power to produce light comparable to a 75 watt bulb. Better yet, their lamp "life" of 50,000 hours means they can burn 5 hours a day… for up to 27 years! (Incandescent bulbs usually last from 750 to 2500 hours, depending on size and use.) LEDs are available in several color temperatures (see below for a definition of color temperature), depending on the manufacturer. I find that 2700 to 3000 degrees Kelvin is a color range very similar to incandescent lamps. These recessed can lamps typically fit in a standard six inch recessed can fixture, although some manufacturers have specific cans designed for their lamps.

I installed five LED lamps in the 28 year-old recessed cans in my kitchen. I think they put out better light than either the original incandescent bulbs or the compact fluorescent lamps I had been using. Based on their light output and low power use, I would recommend this type of fixture in any home that uses recessed can lights. The newer models are dimmable. Although they may have a higher initial cost compared to other light bulbs, LEDs will pay for themselves by reducing power bills and because they have an incredibly long life. However, if you have to choose where to put LEDs first, I suggest the fixtures you use most often since they will achieve the most return on investment. The harder to reach the location, and the more the fixture is used, the more you will appreciate the long life and low power consumption of LEDs.

The second place that LEDs are particularly useful is under-counter lighting. Prior to LEDs, the choice was Halogen puck lights (short-lived and hot enough to inflict burns), or fluorescent strips (marginal color rendition and not very popular in my experience). By comparison, LED strip fixtures put out well distributed light with long life, low power consumption, very low profile and minimal heat. They come in a number of strip lengths and can be joined together to make long runs.

To summarize, LED lamps and fixtures have long life, low power consumption, and good light output. Their cost continues to come down and there is an increasing range of configurations. They have major reduction in heat output compared to incandescent lamps and so, in addition to the direct savings from lower wattage, they have a significant saving in air conditioning cost. If you haven't used them yet I recommend that you start.

I don't have a big budget but I could not afford not to use LED fixtures in the recent remodel of my own house. Between the lights, higher efficiency air conditioning, solar water heating, and better insulation I am already seeing a reduction in my power bill. That bill will be coming in long after the costs of the remodel have been paid for.

# # #Copyright © 2011 by Jeffery M. Wolf All rights reserved.###

So, why do we measure the hue of the light as a "temperature"?  This was started in the late 1800s, when the British physicist William Kelvin heated a block of carbon.  It glowed in the heat, producing a range of different colors at different temperatures.  The black cube first produced a dim red light, increasing to a brighter yellow as the temperature went up, and eventually produced a bright blue-white glow at the highest temperatures.  In his honor, Color Temperatures are measured in degrees Kelvin, which are a variation on Centigrade degrees.  Instead of starting at the temperature water freezes, the Kelvin scale starts at "absolute zero," which is -273 Centigrade.  (Subtract 273 from a Kelvin temperature, and you get the equivalent in Centigrade.)  However, the color temperatures attributed to different types of lights are correlated based on visible colors matching a standard black body, and are not the actual temperature at which a filament burns.

Source: Digital Lighting & Rendering by Jeremy Birn

This is an excerpt of a page found at 3drender and is used by permission from the author who was kind enough to return the call of a total stranger. There is a lot more information on that site if you care to look it up. The page within the site is colortemp.html

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