LED lighting has been continually evolving over the past few years. I attended a session at Better Buildings By Design in February given by Peter Romaniello on LED lighting, and Peter warned us that there was a lot of junk on the market. He gave us some criteria with which to evaluate LED products.
- Does it have a Lighting Facts label? If not, pass it by
- Is the color temperature between 2700 and 3000K?
- Is the Color Rendering Index (CRI, called Color Accuracy on the label) at least 80?
- If it is dimmable, does it need a special dimmer (some do...)?
- Is the distribution of light appropriate for the use (Peter showed some examples where good conventional lighting was changed haphazardly to LEDs, resulting in alternating pools of light and dark)?
- Is it a viable replacement for existing technology?
- Will it become rapidly obsolete?
One of the flagship companies making LED light engines is Cree. They've partnered with Home Depot to sell the EcoSmart LED downlight, designed to retrofit into existing standard six inch recessed lights. It's marketed as a direct replacement for a 65W incandescent that many of these fixtures were intended for. According to the Light Facts label, its light output is 575 lumens, it draws 10.5W, its color temperature is 2700K, and its color accuracy is a high 92.
Our kitchen has three six inch Halo cans with a white trim ring and a gold reflector cone. The lamps in these fixtures were 23W compact fluorescents, the ones that look like dairy whip cones. They are rated at 1640 lumens, almost three times higher than the Ecosmart lamp. They have a CRI of 82 and a color temperature of 3000K. I took my light meter out and measured light levels at my counter of 12-15 footcandles - not too bright, really (no comments about similarity to the blogger, please!). The interaction of the lamp and the gold reflector didn't produce a pleasing light quality. Armed with how-to info from watching a couple of Youtube videos on how to install the Ecosmart lamps I swapped them in and the CFLs out in fifteen minutes - you remove the trim ring and reflector, then the mounting plate that holds the porcelain lamp socket in place, then you screw the LED lamp in place, and snap it into the recessed can, where it is held by three leaf springs mounted on the LED.
The difference in lighting quality is profound. The kitchen feels brighter and cleaner. Jill noticed it last night when she came home and she thought it was a huge upgrade. Interestingly, the light levels are barely higher - maybe 15 - 17 footcandles. This shows that the lumen output of the lamp doesn't tell the whole story - what matters is how the system of the lamp and the fixture move the light of the lamp to the place we want the light to fall. The CFL lamp is not well matched to the recessed can application, so it was easy to do better with fewer watts and a lot fewer lumens.
Other advantages of the LEDs are even longer lamp life (but who knows really, they haven't been around 35,000 hours yet :-) and no mercury (fluorescent lamps have small amounts of mercury in them.)
I like the light quality, but I really want a 20W version to boost the light levels for my middle aged eyes. That would likely be a true replacement for the 65W incandescent lamp in most six inch cans. These things aren't cheap - even through Home Despot they're $30 (earlier they were $20, and some places they are more - I think the targeted list was $50.) I figure these three Ecosmarts will save me a bit over 40 kWh/year, currently costing about $7.50. Not horrible economically, and less money than what it would cost to purchase solar electric panels to generate this energy.
Of course, one can always keep the lights off and wear a Petzl LED headlamp!