Energy Efficient Can Lights with CFLs
Recessed can fixtures offer a great option for energy efficient lighting. Common size recessed fixtures are rated for up to 150 watt incandescent bulbs. These same fixtures can provide fantastic lighting using a fraction of the energy by replacing the incandescents with compact flourescents (CFLs).
A typical 200 sq. foot room will be well lit by six recessed can lights, each with 100 watt bulbs. Using traditional incandescents, this means 600 watts of light. Assuming 6 hours of use each day, that’s 3.6 KWh each day, or 108 KWh / month. At $0.15/KWh, that’s a whopping $16/month to light just one room.
Instead of using traditional light bulbs, replace those incandescents with compact flourescents, and the picture is much brighter. A 23 watt CFL can produce the same amount of light as a 100 watt incandescent. This makes the math easy. a CFL uses 23% of the energy of its energy-sucking predecessor. That means a 77% savings by switching to CFLs. Our $16/month bill for one room of CFLs is reduced to a mere $3.72.
So what’s the drawback? Not much. CFLs take slightly longer to warm up to full brightness, about 15-30 seconds with most bulbs in a 70 degree room. (Warm-up takes longer in colder ambient temperatures). CFLs also cost about 4 times as much as comparable incandescents, but they last as much as 5-10 times longer. Most are rated for 8000 – 10000 hours of use. In our example, that means we’d only replace a light bulb about once every 4 years; so the up front cost isn’t much of a drawback.
One drawback in prior years was that CFLs could not be dimmed, a major detractor for those of us who love to use our recessed lighting to set a mood. Not so anymore. Many manufacturers have developed dimmable CFLs. They’re available in some hardware stores, and all over online (just search above for “Dimmable CFL”)
What do you think? Have you replaced the bulbs in your recessed can lights? Are CFLs still in your future?
Photo courtesy of iLoveButter.
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7 Responses to Energy Efficient Can Lights with CFLs
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September 3rd, 2008 8:13 am
I have 25 floodlights, four dimmable, which I’m gradually replacing. While they still take 20 seconds to warm up the light they give out is much improved over the first generation CFLs, and the savings have been proven in each month’s smaller electricity bills.
I haven’t found an outdoor GFL floodlight yet though. Does anyone know if they exist?
September 3rd, 2008 11:01 am
Absolutely good advice, especially for can lights. I have 13 recessed fixtures in my basement shop which originally had 75-watt incandescent bulbs in each. That was nearly a kilowatt hour of juice before turning on a shop tool.
I replaced them all with CFLs three years ago and found another benefit: less heat. With the 7 foot ceiling in my shop and the minimal ventilation, those incandescent bulbs made the shop steamy very quickly. It’s at least five degrees cooler since I replaced them with CFLs.
One thing I’d recommend is to stay away from off-brand bulbs as well as Phillips. I saw way too many early failures with them. I stick with Westinghouse now.
September 3rd, 2008 3:44 pm
You know, I keep looking at those bulbs in the store, but every house I see with them has this horrid, eerie, greenish tinge to it! Have they developed new bulbs yet that look more like incandescant light? (The fluorescent lights at school used to give me migranes.)
September 3rd, 2008 5:27 pm
It’s more bluish than greenish. Incandescent light bulbs give off a yellowish color, around 2700 degrees on the Kelvin scale. Daylight is around 5000K. CFLs are commonly sold with different color indexes ranging from “cool white” (which approximates daylight) to “warm” or “soft” white which has less blue in the phosphors and more closely approximates incandescent bulbs.
After a few years of living with CFLs I actually prefer their color balance now, which is closer to daylight (although this might have something to do with my house having so much natural oak, which is yellowish). I imagine that when Edison introduced the electric light bulb that people had much the same argument then about these new-fangled bulbs versus the even yellower color of candle light.
September 3rd, 2008 5:35 pm
I’ll second Steve’s opinion. We switched to CFLs after finding ones that are slightly whiter than incandescents, but don’t have the harsh blue/magenta color you cited. After 5 months of use, I’m sold. The light is still easy enough on the eyes, and the energy savings are tremendous — hundreds of dollars in savings over the course of a single year.
September 5th, 2008 9:36 pm
These look great – are these your kitchen?
September 5th, 2008 9:41 pm
Hi Mary–actually that photo is one I borrowed from Flickr Creative Commons (attribution at the bottom) – but the kitchen is done. We’ll probably write about it next week… We’re sanding the stipple tomorrow.