Comparing LEDs and Incandescents
Lighting designer Randall Whitehead advises a reader on the right lighting for a green building.
Randall, I am a vocal advocate for green building and lighting. Is there an equation to compare LED to incandescent watts? I have a customer who is very interested in LEDs, and we are retrofitting with LLF retrofit cans. What’s your opinion about that product? Can you get dimmable LED recessed lights? Do they fit in regular cans? Also, what insight can you give regarding the future of LED overhead lights in commercial applications?
I’m a big fan of green design, as well. My whole house is either fluorescent or LED (except for the bulbs in the fridge and the oven). I retrimmed my existing 6-inch cans with LED retrofit kits, and yes, they are dimmable. Unfortunately, there is not a simple formula to convert an LED light output into an incandescent equivalent. It is still mostly subjective. It depends on the LED manufacturer and color temperature. Cool-colored LEDs tend to give more light than warmer-colored. In my own experience, manufacturers tend to give a higher lumen output than what I see in reality. This was true in the industry long before the advent of LEDs. For example, I can attest that a 12W LED MR16 gives 35W worth of light in the spot version and 20W in the narrow flood version, which is a bit less than what manufacturers are putting out there. As far as retrofit trims go, the Permlight 6-inch LED downlight trims (www.permlight.com) give around 65W worth of light for 15W of LED. The LLF 6-inch (www.LLFinc.com) is a bit more, but with a more even distribution. They say that the 12W gives 650 lumens. To keep homeowners happy, always get the 27K version. People tend to shy away from cooler color temperatures (even though they are great for closets and laundry rooms); they just want an incandescent quality of light. They don’t know that LEDs and fluorescents come in different color temperatures. They are used to using incandescent sources that are all basically the same color. LEDs may be too dim for high-ceiling commercial applications at this point, but I have great faith that this is possible in the very near future. Fluorescent is a better choice for the here and now. Although, I would still warn people that fluorescent lamps have mercury in them and need to be treated as toxic waste and disposed of safely. The LLF website does show some pretty convincing commercial applications, though, so I may revise my opinion when I check them out in person. Seeing is believing.
Randall Whitehead, IALD
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