25 August 2013

Nanolight LED bulb strives for efficiency at any cost, repeats mistakes of the CFL

The Nanolight, a high-efficiency LED bulb, made waves in both Kickstarter and the LED lighting community at the start of this year when the project picked up over 5,000 backers and $273,000 in crowdfunding. The Nanolight didn’t just turn heads because of its unusual design, it was billed as the “most energy efficient [LED bulb] on the planet”. Not being an LED manufacturer and seemingly possessing no special technology, this was a rather incredible claim.

Producing 1600 lumens while running at 12W, the Nanolight was slated to put out an incredible 133 lumens-per-watts, or roughly double that of a standard consumer LED bulb. 1600 lumen (100W-equivalent) LED bulbs are still relatively rare, but Philips has one that sells for $40 and runs at 22W. (That’s 80.9 lumens-per-watt if you don’t have a calculator handy.)

These two images offer the best explanation I could think of. First, the 10W, 1200 lumen Nanolight LED bulb that I purchased. 

And now, a Cree LED bulb, available at any Home Depot store.

Images are cropped, but otherwise unedited.

You can see a significant difference between the two, even though these are just standard smartphone shots. Nanolight, curiously, did not include any mention of CRI or color temperature in its original Kickstarter posting. This, of course, wasn’t a great sign.

The intended color temperature was apparently 4000K, but the team ended up going with a less harsh 3500K. The decision was made clear in a comment on March 4 (funding closed on March 8). After some questions, it turned out that the CRI would be “about 70,” a fact that was added to the Kickstarter’s FAQ page at some point. That’s quite low for consumer lighting, with a color rendering index of 80 generally being seen as an acceptable starting point (thanks in part to 80 being the minimum number for Energy Star approval). It’s not clear what the Nanolight’s actual CRI is, but it’s not great.

The full FAQ answer goes as follows (emphasis not added): “There is always a trade off between efficiency and CRI. For the moment, NanoLight’s CRI is about 70 and we are working to increase this factor as much as we can WITHOUT decreasing the efficiency.”

Integrating sphere, used for lamp testing.

Increasing CRI without decreasing efficiency is a great concept, as would be driving more using the same amount of gas. The problem, as so often is the case, is that there are direct tradeoffs for these things. If you want more efficiency, that means less light quality (providing you don’t bring any technological improvements to the table). The Nanolight team could have hit a CRI of 80, 90, or even 95 easily enough with the right LEDs and/or the use of different phosphor, it would just have lost efficiency each step of the way. And, unfortunately, by the time the Nanolight got to an acceptable CRI level, the product would likely have been left with a bulb that performed just like a standard LED offering but that used their unorthodox origami design. In other words, the Nanolight is an interesting concept but you can’t get something for nothing.

It’ll be up to the project’s backers to decide if they feel the team was less than fully transparent about the performance of the bulb. As a backer, I can say that I’m disappointed with the end result and don’t feel it’s good enough for indoor use in a residential setting. This is exactly why LED lamp manufacturers like Philips, Cree, and Switch talk so much about light quality and resist getting into an efficiency arms race with one another — the companies know things will not end well. Maybe this all amounts to another problem with Kickstarted hardware, maybe it doesn’t. Most comments on the Nanolight’s page have to do with slow product delivery, not light quality.

Most consumers don’t know about things like CRI and color temperature, they just know when they see a light that doesn’t work for them, which is what happened with many CFLs and what larger manufacturers took pains to avoid with LEDs. So far it’s going well, but if we start demanding unrealistic efficiency numbers there is going to have to be a tradeoff that we’re not happy with.

Now read: Piezo-phototronic nanowire LEDs can scan your fingerprint, and then display it back to you.


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