Attack of the (sort of) Killer LEDs

As part of my campaign to reduce energy consumption, I've been eyeing LED bulbs as the ultimate in lighting efficiency. However, as I mentioned some posts back, they do have their drawbacks - primarily lacking sufficient light to be useful everywhere a standard incandescent or compact fluorescent bulb can go.

To dip my toe in the water, I targeted a nice antique chandelier light in my dining room. It currently has five 40W candelabra bulbs in it - burning a precious 200W when turned on. I use this light quite a bit, so reducing power consumption here will likely result in an overall measurable reduction in energy use.

My first pass was to pick up five LED replacement bulbs from the folks at superbrightleds.com - specifically the 21-LED model shown below.

The first test failed, in that my wife came home and spotted something "wrong" with the fixture even though it wasn't powered - the shape and size difference threw her. Powering them up at night, the 5500K super white color was pretty neat and got a "cool" vote from my 4-year-old - but was eerily different from any other light sources in the room. However, the real problem was insufficient light - very noticeable on the table surface below (at the elevation of the light and above, not too bad). This was quite a bummer, since I was really hoping that at 2W each, I could take this fixture from 200W to 10W in power use.

So it was back to the drawing board and for once timing was in my favor. The superbrightleds.com folks had just added a brighter 32-LED candelabra bulb to their catalog and as a bonus it comes in the traditional aesthetic shape.

This time around I opted for warm white LEDs and combined with the additional light output ended up with improved lighting quality and something I can work with. These bulbs consume 3W each - not bad going from 200W to 15W total energy consumption for the fixture (that's a decrease of 92%).

I am going to stick with this setup, although I would give it a B or B- in terms of being a true drop-in replacement. First, the actual light intensity is noticeably less than the original incandescent bulbs. The claim is that these are rough equivalent to a 25-30W bulb - a lumen-for-lumen replacement for a 40W (or higher) bulb simply doesn't exist. Second, the light emitted does not saturate an area like an incandescent or CF bulb - by their very nature, LEDs appear to be highly directional light sources with narrow beam patterns. Finally, my wife made me promise to keep the old 40W incandescent bulbs around "just in case" we want to swap them out for the random dinner we may host - the LED bulbs have a space age appearance that may not be the best mood lighting for a quiet dinner. And for the icing on the cake, these bulbs are pretty heavy on the pocket book.

I have a few other LED replacements projects in the works and I'll report on those down the road. But for now, LED light technology isn't here yet in terms of being decent 1-for-1 replacements for existing conventional bulbs. I hope this does not remain the case for long.... but it took a while for CF bulbs to get into the mainstream and to be reasonable replacements - I suspect LED bulbs will follow a similar path.

Comments

[henri]

Seems to me that there should be some advantage to switching to a DC system for lighting:

- I'm pretty sure LED lights would be more efficient

- easier to generate DC power (via solar power) and store it in deep cycle batteries

- shouldn't be too hard to build a the server at home that runs off of 12v (for the HTPC for example)

My folks in Beirut run 2 deep cycle marine batteries and have a secondary 12v power system running in the house. They use it to power fluorescent lights that are run with out a ballast (and flicker free!) when the power is out. Back in the early 90s when we had no power for a few months we would fire up a generator to charge up the batteries, but normally they use a regular battery charger.

[Chris Staszak]

I'm not quite at the point yet to seriously shop for a home solar electric solution - but one of my questions will be whether it is possible (or practical) to have a few DC drops in the house along with normal AC power via inverter. One big ticket item to wire up with DC would be a refrigerator. Or racks of home servers with a 48 VDC backplane :)

Efficiency aside, the LED output just isn't there yet. For now I am believer for specific, targeted uses - not a general replacement for conventional bulbs.