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redditLifetime of Light Source: how many hours of operating life are lost when you cycle off/on a light?
My previous post on energy savings per light bulb really left me wanting more data on how number of times turning a light on/off affects the operating life of the bulb / lamp. Maybe the additional energy isn’t much, but what about the wear / stress on the bulb’ and its operating life? So I found another source of info:
http://www.energysavers.gov/your_home/lighting_daylighting/index.cfm/mytopic=12280
It prefaces that the (exact number of hours that switching lights on and off reduces the total operating life depends on the type of light and how many times it is switched on and off), and gives a generalization for two very common types of lights:
Incandescent lights: 85% to 90% of the energy is turned to heat (not light), and the actual bulb is cheap (relative to the cost of energy), so they should be turned off when not needed – especially if you’re just in another room.
Fluorescent lights: relative to incandescent lights: the lamps cost more, lifetime is reduced more per off/on cycle, and startup time uses more energy. The energysavers.gov link claims that a good estimate may be to turn it off if you’re leaving the room for more than 15 minutes (this number may be smaller if you have a very low cost of energy). Apparently this can also vary based on both bulb and the ballast.
In some apartment complexes, they will replace the main common area large fluorescent tube lights (and ballast) for free. For such a situation, this would mean to use the 23 sec number (from the Discovery Channel MythBusters test in my previous post) (energysavers.gov said 5 sec) rather than the 15 min number.
Here’s another source, US Energy Star:
http://www.energystar.gov/index.cfm?c=cfls.pr_cfls
Maybe it’s really the same source, but in any case, here it also says, for compact fluorescent lamps (CFL’s), to maximize the lifetime savings and effectiveness of your CFLs by keeping them on for 15 minutes or more at a time.
It also mentions that CFL’s should avoid extreme temperatures (hot or cold) since that can reduce lifetime, and being in an enclosed fixture with no airflow might cause it to generate heat and reduce its lifetime.
Pem (Admin) :: Oct.29.2009 :: Electricity :: No Comments »
