Compact fluorescent lamps (CFLs) have become more popular in recent years, but d
ID: 2630118 • Letter: C
Question
Compact fluorescent lamps (CFLs) have become more popular in recent years, but do they make financial sense? Suppose a typical 60-watt incandescent lightbulb costs $0.47 and lasts for 1,000 hours. A 15-watt CFL, which provides the same light, costs $3.50 and lasts for 12,000 hours. A kilowatt hour of electricity costs $0.123, which is about the national average. A kilowatt-hour is 1,000 watts for 1 hour. However, electricity costs actually vary quite a bit depending on location and user type. An industrial user in West Virginia might pay $0.04 per kilowatt-hour whereas a residential user in Hawaii might pay $0.25.
You require a return of 9 percent and use a light fixture 500 hours per year. What is the break-even cost per kilowatt-hour?
Compact fluorescent lamps (CFLs) have become more popular in recent years, but do they make financial sense? Suppose a typical 60-watt incandescent lightbulb costs $0.47 and lasts for 1,000 hours. A 15-watt CFL, which provides the same light, costs $3.50 and lasts for 12,000 hours. A kilowatt hour of electricity costs $0.123, which is about the national average. A kilowatt-hour is 1,000 watts for 1 hour. However, electricity costs actually vary quite a bit depending on location and user type. An industrial user in West Virginia might pay $0.04 per kilowatt-hour whereas a residential user in Hawaii might pay $0.25.
Explanation / Answer
QUALITY: You can't trust what mfrs say. For example: with CFLs, the 60w "equivalent" really isn't; you need 75w or 100w "equivalent" (depending on mfr) to equal the perceived visibility you had with a 60w incandescent. LEDs are still too new to have any kind of standard.
BRIGHTNESS: LED and CFLs both loose lumens over time. They can last many years, but you won't be able to read by their light all those years.
LIFESPAN: Depends on what USE the bulb gets (frequently on and off? or on for a while and then off the rest of the time?), and WHERE the bulb is used (over a stove? hallway? outside? bathroom? ceiling fan?)
RADIATION: Some CFLs have the added danger of emitting ultraviolet (UVA & UVC) radiation, if the inner coating has flaws, so they shouldn't be used in fixtures used close to your body for long periods of time (like a desk, reading or bedside lamp).
http://nlm.nih.gov/medlineplus/videos/ne...
http://sciencedaily.com/releases/2012/07...
http://commcgi.cc.stonybrook.edu/am2/pub...
TOXICITY: When a CFL breaks indoors, you need to follow a laborious procedure to clean it up properly. The broken glass of incandescents is safer than exposing your self, family & pets, to the mercury that escapes when fluorescent bulbs are repeatedly broken. One bulb isn't a problem, but mercury accumulates in the body (like lead, it never gets excreted):
http://epa.gov/cfl/cflcleanup.html
http://osha.gov/SLTC/healthguidelines/me...
http://energystar.gov/ia/partners/promot...
Not sure if we have any calculation that accurately covers all these variables
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