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!
Burning Down the House
I installed an ECOSMART (HomeDepot/Cree), 9 watt, A19 in the hanging fixture between 2 existing curlyque flourescent bulbs over the kitchen counter. The yellow banana, red cell phone, green plastic candy box and an orange placed directly under the LED were much more pleasing to look at than under the curlyque.
Only problem is the $17 price tag. I'll be buying a bunch more as soon as the price hits $8 each.
Heather says she enjoyed the light from the LED while cooking during yesterdays rain.
Posted by: Christopher Yaun | 04/12/2011 at 06:59 PM
Marc,
I took notes from your post and used them to stare at the LED display at Home Depot for a very long time (they kept asking if I needed help, I politely declined). In the end I purchased 3 "40 watt equivalent" ecosmart bulbs to test out in the Yestermorrow library. I really like the bright light quality, especially for reading. Efficiency Vermont is running a commercial rebate right now for LEDs that pretty much covers the whole cost of most bulbs, so I'm looking at where else we can try them out (since most of our buildings use flourescents already that have hard-wired ballasts, there are very few to switch out).
I was also interested to read the article in this month's Fine Homebuilding which talks about the new Lutron dimmers for LEDs and CFLs, which I might test out at my house.
Posted by: Kate Stephenson | 04/29/2011 at 08:20 PM
A gold-flash Halo optometrics aren't really designed to optimize the output a 23W twisty CFL. A better comparison would be a 12-16W R30 vs. your new Cree CR6s.
A couple issues with the $30 box-store CR6s are:
The color temp isn't super-consistent unit to unit- some are redder/lower temp than others, not by a huge amount, but noticeable.
On many dimmers they flicker, but with newer Lutrons they might flicker at only a couple of levels, but otherwise dim smoothly. Incandescent dimmers are maladapted for running electronic ballasts, so I don't fault the Cree design for this- quite the contrary, I'm impressed that it works as well as it does with SCR wave forms on the incoming power! The Cree CR6 works far better on dimmer control than any Edison base CFL or CCFL out there.
Like the LR6, they're fairly low-glare compared to the competition, and lower glare than some R30 CFLs of similar output. At the box-store price point they're a good value particularly for high CRI dimming applications, but for non-dimming fixtures R30 CFLs may still beat them on lifecycle cost & luminous efficiency. If and when the L-prize PAR 38s arrive on the market it'll be another story entirely- more than twice the light per watt, for a similar initial price point (and cheaper thereafter), if any LED manufacturer is willing to step up to the plate on that one.
Posted by: dana | 05/16/2011 at 06:00 PM
Thanks very much for this post! Do you have a LED lamp in the range you suggest that you prefer? I'd like in some applications to have up to twice as much light output as this 10.5W Cree lamp. And do you have a recommendation for a screw-in LED lamp for a pendant fixture that doesn't have too narrow of a beam spread (over an island)?
Thanks
Posted by: Marc Rosenbaum | 05/17/2011 at 06:07 PM