[SustainableTompkins] Comparison of various light bulbs

[Thomas Shelley]

Dear Friends--I thought this was quite interesting.  Forwarded from the 
Fostering Sustainable Behavior Listserv.  My apologies for any 
cross-postings.  Tom

>From: "Morse, Mary" <Mary.Morse at sanjoseca.gov>
>To: Fostering Sustainable Behavior Listserv <fsb at cbsmlist.com>
>Date: Tue, 6 Nov 2007 09:03:45 -0800
>Subject: Re: Still good incandescents? [TS comment:  title of original 
>thread.]
>
>Lights On or Off
>
>Myth: You save on energy bills by leaving lights on. Some people believe 
>that the energy to turn on lights exceeds savings of turning lights off. 
>They talked to Mark Reisfelt, manager of the Independent Electric Supply 
>where they purchased their light bulbs. He felt that it was best to turn 
>the lights off. To test the myth, they needed to measure energy usage 
>during startup, maintenance (steady state), and shutdown. For steady state 
>energy consumption, they turned on several different types of bulbs for 60 
>minutes and measured their consumption using a 
><http://www.thinkgeek.com/gadgets/electronic/7657/>Kill A Watt:
>    * Incandescent 90 Wh
>    * Compact Fluorescent (CFL): 10 Wh
>    * Halogen: 70 Wh
>    * Metal halide 60 Wh
>    * LED: 1 Wh
>    * Fluorescent: 10 Wh
>
>For startup energy consumption, Grant hooked up an inductive current loop 
>to a computer and measured the amount of energy used when the turned on 
>the bulbs. With an inductive current loop, you run a wire through the 
>center, which induces a current in the loop. This current is then measured 
>by a digital sampling oscilloscope.  Based on the amount of energy 
>consumed turning on the bulb, they were able calculated how long the bulb 
>would have to be turned off in order to make it worth the energy savings, 
>i.e. "It's best to turn off the bulb if you are leaving the room for":
>    * Incandescent: 0.36 seconds
>    * CFL: 0.015 seconds
>    * Halogen: .51 seconds
>    * LED: 1.28 seconds
>    * Fluorescent: 23.3 seconds
>
>In other words, its almost always best to turn the bulb off. Even the 23 
>seconds for the fluorescent lights isn't very long, and the rest of the 
>times are pretty much blinks of an eye.
>
>Bulb Longevity
>
>They tested one final element of this myth: frequently turning lights on 
>and off decreases their life span, thus leading to greater costs. Grant 
>setup a timer and relay to turn the bulbs on and off repeatedly every 2 
>minutes. After six weeks, only the LED bulb was still working. Based on 
>this test, they extrapolated that it would take five years of ordinary 
>usage to cause the bulbs to burn out.
>
>
>
>(Source: 
>http://kwc.org/mythbusters/2006/12/episode_69_22000_foot_fall_lig.html)
>
>
>
>Mary Morse
>
>Associate Environmental Services Specialist
>
>City of San José Watershed Protection
>
>170 W. San Carlos Street, San José CA 95113
>
>phone: 408-277-2767 fax 408-277-5775
>
>are you water aware? 
><http://www.sanjoseca.gov/esd/water-awareness.htm>http://www.sanjoseca.gov/esd/water-awareness.htm

Tom Shelley
118 E. Court St.
Ithaca, NY 14850
607 342-0864
tjs1 at cornell.edu
http://www.myspace.com/99319958