Look Ma, no heatsink! After the innovative flat LED, here comes the hollow one (review)

Cree 60w-equivalent hollow LED lightbulb
© Michael Graham Richard/Cree

Great to see so much progress in energy-efficient lighting

I've been quite impressed with how clever Philips was with their relatively new SlimStyle LED lightbulb (now available in 60W-equivalent and 75W-equivalent models). Here's what they look like:

© Philips

The main innovation is that Philips found a way to drop the heavy and expensive metal heat-sink altogether by flattening the bulb in such a way that there's a large surface area and the individual LEDs are spaced far enough apart to keep cool. Thanks to this unique shape for a lightbulb, prices could be dropped under $10 (and only a few bucks in places where utilities give out rebates for energy-efficient lights) and the LED revolution could gather even more momentum (remember that 70% of lightbulbs in the U.S. are still the old wasteful models).

© Michael Graham Richard

Cree, one of the leaders in the LED field, apparently thought that this was neat, but that they could do even better. They created a LED bulb that also doesn't have a metal heatsink, but rather than make it flat, they kept it the regular lightbulb shape and instead hollowed it out, with vents so that air could flow through - what Cree calls its "cross-flow convection technology" - and keep the LEDs within the safe temperature range (see the image at the top of this post for a computer-generate cutaway of the inside of the bulb, with blue and red arrows showing the airflow pattern).

© Michael Graham Richard

On the photos above and below, you can see my attempt at showing the inside of the Cree bulb. The yellow things are the actual light-emitting diodes (LEDs), and the rest is basically empty except for a X-shaped plastic core that supports the LEDs.

Another benefit is that the outer part of the bulb is also plastic, so it is shatter-proof, which is a big advantage over CFLs and incandescents, as well as some LEDs that still use glass.

© Michael Graham Richard

The unbearable lightness of being...

According to Cree, this shape is superior to the Philips SlimStyle shape because it allows for a more even omnidirectional distribution of the light. I can see how that makes intuitive sense, though I have to admit that to my naked eye, the difference was not apparent. The LED bulbs from both manufacturers do a very good job of sending light in every direction as far as a I can tell.

Where this might matter more is for people who are very sensitive to what they lightbulbs look like. Some people never got into compact fluorescents (CFLs) because they didn't like the "weird" look, so the flat SlimStyle isn't exactly going to convince them. The Cree bulb looks much more "normal", and at a glance it can almost pass for an incandescent bulb.

© Michael Graham Richard

In any case, the Cree bulb is very interesting, and most importantly, it has very desirable characteristics:

Available in 40W-equivalent and 60W-equivalent models using respectively 6 watts and 11 watts. They produce 460 and 815 lumens, for an efficiency of 76.6 lumens/watt and 74 lumens/watt. They are dimmable.

© Michael Graham Richard

The all important color rendering index (CRI) is 80, and they are available in soft white (2700K) and daylight (5000K) color temperatures.

They are rated at a 25,000 hours lifetime, which is at least 25X the typical incandescent.

© Cree

I've been using my review unit in my office for over a week now, and this is a LED bulb that I could easily live with. In fact, I like it enough that I wouldn't mind using it all around my apartment. The only thing missing is a 75W-equivalent models, and ideally also some 100W-equivalent models for larger rooms. I'm sure those will come over time.

Available as 40- and 60-watt replacements, the New Cree LED Bulb is available at The Home Depot (scroll down the page a bit) for as low as $7.97.

Via Cree

Tags: Energy Efficiency | Energy Star | LEDs | Lighting

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