Dec 20 2011

Are LED Lights Coming?

The BBC reports on a field trial of LED light (light emitting diodes) that is, pardon the pun, glowing. I agree with many of the points made, but there is a distinct lack of pointing out the current downsides to LEDs.

LEDs have many advantages. The bulbs can now be made to produce white light. The study reports that generally the reaction to the kind of light put out by the LED fixtures was positive – more like daylight. I don’t think this is a function of LED technology, however. Incandescent bulbs come in several varieties, such as soft light or harsher light, and you can generally find one that you like. Compact fluorescent bulbs do not have as much variety in the color or softness of the light they produce, and some people find them a bit harsh.

It seems that the LED fixtures that were put into place were brighter than the bulbs they replaced, so people could have been responding to the increase in brightness rather than the color of the light. I purchased a few LED bulbs to see what they were like. I find the color of the white light to be acceptable, certainly not a barrier to use.

Of course, the big advantage of LEDs is that they use 90% less energy than incandescent bulbs. Interest in LED is driven mostly by the fact, especially on the part of governments looking to reduce energy costs. LED bulbs also last about 100 times as long as incandescent bulbs and 6-7 times longer than CFLs. This is a nice feature for two reasons – the overall cost of using the bulb, and the inconvenience of having to change light bulbs. I know this is not a big deal for the average domicile, but there are some fixtures that are in difficult to reach places. If I have to get out a ladder to change a light bulb, I consider that inconvenient. There are a couple of outside fixtures on my house that I am not sure how I will change when the time comes. I’m sure I’ll figure it out, but it won’t be easy. Also, consider a large office building or hotel. Keeping all the bulbs burning is probably not a small task.

The article mentions one drawback to LED lights – their initial cost. At my local Home Depot a standard 60w equivalent LED bulb is now selling for $25 (prices have come down even in the last 6 months, since the last time I looked). The 40w equivalent are only $10. Still – think about replacing all or most of the bulbs in your home with LEDs. For most people this is not an insignificant investment. It is cost effective, given the decreased energy use and life expectancy of the bulbs, but it’s still hard to make that initial outlay. (The money savings is over the lifetime of the bulb, which is 46 years – that a long term investment.) It is a significant psychological barrier to transitioning to LEDs. Fortunately, prices are coming down and will come down further as the LED market grows.

At present the single most limiting aspect of LEDs was not even mentioned in the BBC article – LEDs are very directional. They project light in only one direction, not diffusely in all directions like an incandescent bulb. For the test bulbs that I purchased I found this feature to be stark – the bulbs are more like spot lights. In fact, LEDs are great for spot lighting, but are problematic for room lighting. For most of my fixtures, I found this feature to be unacceptable. At present it is the only reason I am not switching entirely to LEDs – all the more reason that I was disappointed this was not even mentioned in the article.

There are partial fixes to this problem. You can have a light fixture that acts to diffuse the light, rather than having a naked bulb. For me, this would mean changing most of my lighting fixtures, which is not a very convenient option. Improving this feature of LED needs to be a priority, in my opinion, before gaining wide acceptance.

That is another question raised in the BBC article – how to get more people to use LEDs. LEDs use less electricity, which will reduce energy costs. But I would like to see a thorough assessment of their net environmental impact, including the cost of manufacturing and disposal. I suspect they will still be a net advantage, but I could not find a good source on this.

The best way to get people to use LEDs is to make them the more attractive option for consumers. That’s it. LEDs are moving in that direction, and for some applications are already there. I haven’t found a bulb that I would use in most of the fixtures in my home, because of the directional issue, but I continue to look for new options. I am also glad to see the prices coming down, but they are still a barrier.

Meanwhile, OLEDs are on the horizon – organic LEDs. These are even more efficient than LEDs, do not have the directional problem, and can be made into flexible panels. Life expectancy is about 5,000 hours (about 1/20 of LEDs). At present OLED lamps and panels are extremely expensive (hundreds of dollars for a small panel, and thousands of dollars for an OLED desk lamp). They are not yet ready for prime time. Mass production is just starting, however. Perhaps in 5-6 years they will come down to consumer level pricing.

There doesn’t appear to be one perfect option coming anytime soon. The perfect option would be a bulb that can work in existing fixtures, with a pleasant omnidirectional light, long life, low energy usage, inexpensive, and using no toxic materials. LEDs are close – they just need to fix the directional problem (meanwhile they make great flashlights).

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