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Watts and Lumens – Old and New – Complicated or Simplified??

Ask most folks what light they have above the kitchen sink and common response is: “A 60 (or 75) watt”. More recently the answer might be: “A CFL (Compact Fluorescent Lamp)”. Much like the Dylan song….”The Times They Are A-Changin’”, new lamp terminology is being tossed around like a hot – well…incandescent light bulb.

A watt is a unit of electricity and lumen is a measure of light. With the advancements of CFL and LED technology, we are getting the same amount of light from less electricity.  The term for the relationship of electricity used and light produced is efficacy (or lumens per watt).  Basic understanding of this terminology will aid in deciphering the new Lighting Facts Label, required by the FTC starting Jan. 1, 2012.

Patterned after the FTC’s (Federal Trade Commission) “Energy Guide” labeling program for appliances that started in the 1980’s and the FDA’s “Nutrition Facts” label that began in the 1990’s the new label will help consumers comparatively value modern choices for lighting.

The below samples of the Lighting Facts Labels illustrate the difference in energy used in watts for relatively the same lumens. The chart displays the cost over 18 years – the estimated life of an LED lamp. Another consideration would be the cost/inconvenience of changing the lamp which may not be an impact above the kitchen sink but would be if one had 600 fixtures in a poultry operation enclosure.

 

Lamp Type

Lumens

Watts

Lamp Life*

Annual Energy Cost**

Cost of Lamp

Cost of energy and bulb over 18 years

Incandescent

820

60

1.4

$7.23

$0.75

$139.78

CFL

870

13

5.5

$1.57

$4.00

$41.35

LED

840

9

18.3

$1.08

$11.75

$31.19

*Based on three hours on a day

**Based on the national average of 11¢ per kilowatt hour and on three hours a day

About the Author: Jim Luegge

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