Saving Money: Lighting

One of the advertisements you see between streaming clips of the Live Earth is from Philips promoting compact fluorescent light (CFL) bulbs. How much does changing to this type of light bulb save the consumer? I will assume that electricity costs $0.15/kWh. That means if I run something that takes a kilowatt for one hour, it will cost me $0.15. The most abundant light bulbs around the house are 75W incandescent light bulbs, which can be replaced with 18 W CFL bulbs. Most likely you’ll have the lights on in the evening after you come back from work. If you’re one to turn off the lights when you leave the room, that leaves about 3 lights on at one time. So from 5 pm to 2 am, there will be about 3 lights on. 9 hours a day for 365 days a year. For a CFL bulb, 59 kWh are used a year compared with 246 kWh for an incandescent. That’s a savings of 187 kWh or $28 a year. That’s a decent savings. CFL bulbs also last longer than incandescents, so you also save time from changing them less.

CFL bulbs save money, but what are the drawbacks? CFLs used to be more expensive than incandescents, but with rebates they can be purchased for cheap. Those used to office fluorescents may dislike the warm-up period, hum and toggling the switch trying to turn it on. I’ve had problems with humming, but you can often keep switching them until you find one that doesn’t hum. You also should not use dimmers with CFLs since dimmers can cause humming. I’ve never had to toggle the switch back and forth to turn on a CFL. Most CFLs don’t need to warm-up. The only one that needs to warm-up is the one I use for the bathroom. That warm-up period is welcomed, because when you go to use the bathroom at night you don’t want to be blinded and brought out of your sleepy daze. As you get older, you’ll find yourself using the bathroom more at night. The quality of light from CFLs are good, but they do not contain as much red wavelengths as from incandescents. CFLs do not produce as much heat as incandescents, which make them more efficient at giving off light, but the one case in which a CFL can not replace an incandescent is when an incandescent is used for heat, such as some kid’s toys like shrinky dinks and those rotating lamp shades.

Don’t fluorescent lights contain mercury?

According to, you can recycle your CFLs and the net mercury released is less than a incandescent , because mercury is released in power generation.

CFLs are awesome money-wise and environmentally. CFLs are the here and now, but solid-state lighting will be the future. That is for another time.


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