Does Retrofitting linear fluorescent tubes with LED T8 tubes make sense?

Not according to a recent report published by the Department of Energy.

(excerpts from LEDs Magazine-May 2011)

The US Dept of Energy (DOE) has published the final report from an evaluation of three LED products designed to directly replace linear fluorescent lamps in commercial ambient lighting. These three products were among the "best in class" of products designed for this application at the time of the study, as identified by DOEs CALiPER testing program.

Key findings include:

•All three LED products drew less power than their fluorescent counterparts but also provided significantly fewer lumens on the room and work surface grids measured beneath and beside them.
•The prices of the LED products are such that none pay for themselves when compared to the standard T8 fluorescent lamp used as the primary baseline in the study.
•If lower light levels are acceptable, similar energy savings can be achieved much more cheaply by substituting lower-wattage fluorescent lamps. Such lamps also have very long lifetimes (30k + hours) and better lumen maintenance than the LEDs over their lifetime.
Alternative designs, such as panel-type products and overall troffer replacement systems, may prove more effective in the future than the products tested in this study. None of these alternative whole-luminaire designs were evaluated here, as this study focused exclusively on products designed for direct replacement of fluorescent lamps in existing troffers.



The report is available for download at:

http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/gateway_t8-replacement.pdf

Comparing Lumens per watt- The TRUE measuring stick of efficiency

Yesterday, the question arose, "what is the most efficient lighting source available?" The person continued by asking if it's LED yet, or is it still High Pressure Sodium.

For the novice, first let me provide a definition of Lumens per watt, which will be the measuring stick for efficiency. Lumens per watt is defined as "A measure of the efficiency of lamps. It indicates the amount of light emitted by the lamp for each unit of electrical power used". For example, a 100-watt lamp producing 1750 lumens gives 17.5 lumens per watt.

So, I wanted to provide a chart comparing different lighting technologies for you to easily see the differences. However, manufacturer's produce different products which makes it hard to put an exact number down. It is a lot like the gas mileage you get with a car. It is very difficult to say all 4-door sedans get 20 mpg. With that said, here is chart:

Incandescent- 24 lumens per watt
Halogen- 36 lumens per watt
Compact Fluorescent(CFL)- 80 lumens per watt
Fluorescent Tubes- 105 lumens per watt
Ceramic Metal Halide- 125 lumens per watt
High Pressure Sodium- 140 lumens per watt
Low Pressure Sodium- 180 lumens per watt
LED 200 lumens per watt

Does this mean you should change every light fixture in your facility to LED? Whoa, no way. LED has it's benefits and in certain applications it is terrific..in others, however, LED technology may not be the best option. Every area should be addressed individually to best maximize light levels, energy-savings and employee performance.

Welcome!

The purpose of this blog is to help commercial and industrial building owners understand the available lighting technologies, rebates and tax incentives.