We have three different kinds of dimmable recessed lights in our kitchen. Not long ago, Lisa wrote about the cost of using each of those bulbs, a process that was illuminating (couldn't resist) but not all that surprising - the power-saving aspects of energy efficient lighting are well documented.
Recently we had the opportunity to learn about the differences in heat generated by these bulbs. Once again, we knew there would be a difference. The range, however, was staggering. As we enter the cooling season, the value of energy efficient bulbs has never been clearer: our halogen lights are like turbo-charged miniature space heaters. This video shows both the PAR38 dimmable CFL, and the Cree LLF Downlight LED. Both save in more ways than we'd thought.
In fact, as we start to focus on cooling season, I'm not sure we can afford to keep running the halogen/incandescent part of this experiment.
Bulb Type Temperature (Fahrenheit)
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Cree LLF Downlight Module LED: 107 degrees
Philips PAR38 Dimmable Reflector CFL: 167 degrees
Incandescent Halogen: 327 degrees
Comments
That's good info. But why not include the plain old standard incandescent bulb, too?
Posted by Dirk Faegre on Jun 8, 2009 11:08amGREAT!
Posted by Competitive Bro on Jun 9, 2009 7:44amBrief, informative,well done
You win on this one
CB
Great information, new there was a difference in heat conduction but never so drastic, thought provoking. We are currently in the "down to the studs faze" in a 1956 built home in the sandhills of NC and considering many types of lighting. Contractors love recessed, electricians-not so much. With this & other reviews on your site in mind, we are wondering if we should even be considering this type. JC
Posted by Clancy on Jun 24, 2009 3:35amBe careful with this demo since the CREE LED lamp has a large, integrated heat sink at the base of the bulb. The bulk of the heat is not conducted through the lens surface.
Still by looking at the watts you can get an exact comparison. This is the important figure of merit. The LED still wins out but not as dramatic as the published numbers.
Clancy - RE your question, it depends on whether the can extends into an attic space or just into a space between floors. If into an attic space, I wouldn't recommend it since you can't put insulation around the can. In the North, this becomes a heat escape point and a problem with ice damming on the roof. In warmer climates, it can become a point where hot attic air enters or radiates down to the living area. Either way, I think it's a bad idea to use recessed lighting protruding into the attic.
Cree makes luminaires where the can extends down into the room. I think this is technically a much better solution. You'll have to judge the aesthetics.
Posted by Jim on Jul 27, 2009 4:41pm