Recently I had been reading up about LED light bulbs, including the award-winning L Prize Bulb. For a few years they have been saying that LED bulbs would replace compact fluorescent bulbs as LED bulbs get more efficient and less expensive. However, I’m not sure that has happened yet. LED bulbs are still significantly more expensive than CFL bulbs, but LED bulbs aren’t all that much more efficient. They do have some other advantages over CFL bulbs in that LED bulbs don’t get dimmer over the years. And LED bulbs don’t contain mercury. Although I haven’t had any problems with my CFL bulbs, turning them off and on frequently can shorten their lives and some bulbs don’t come at full brightness. So LED’s don’t suffer from any of those things.
I was able to get a good deal on this bulb through NewEgg.com. Regularly $15, it was marked down to $6 including shipping. But the problem is that it is only equivalent to a 30-watt bulb, which isn’t that useful. Also it has a bluish tint to the light. Once I got the bulb, I got some of the specs that weren’t available at NewEgg’s site. The color temperature is 5306K which is definitely cool white. The total output is 336 lumens and it uses 4.93 watts of electricity, so the efficacy is 68 lumens per watt. Lastly, the CRI (how well it renders colors across the spectrum of visible light) is 69, which isn’t that great.
A 40-watt equivalent bulb that I have has 550 lumens of output, using 9 watts for an efficacy of 61 lumens per watt. These “soft white” CFL’s have a color temperature of 2700K. There is no CRI number on the packaging (required as of 2012), but Consumer Reports says that most CFL bulbs are at least 81. And the bulbs were only $5 for a 4-pack.
To me, there is no contest. The CFL easily beats this low-end LED bulb.
You can pay more and get a better LED bulb. Philips makes a 12.5 watt bulb that is equivalent to a 60 watt bulb (72 lumens per watt), but the CRI is still only 80. And using only 0.5 watts less than a CFL, it will take a long time to pay off the $25 price difference.
The L Prize bulb is about $50, uses only 10 watts of power, and has a very respectable CRI of 90. But saving 3 watts per hour, it will take 145,000 hours (17 years of continuous operation) to pay for itself. Unfortunately it probably won’t last that long.
I read about the L Prize Bulb, too, and saw the reference to the heat generated by the light. I don’t know why I thought LEDs were cooler, but heat management seems to be a real problem. You have the waste of heat plus the need to put in materials that draw away the heat. I’m just not see these bulbs taking off. (No pun intended… may not even be one there.)
They produce much less heat than incandescent bulbs and the same or less heat as CFL bulbs. But LED’s dim when they get hot and, unlike flashlights, household lights stay on for a long time, so you have to give the heat somewhere to go or eventually the heat will build up.
I think the ultimate goal would be to get away from the standard bulb and create fixtures and circuits designed for more efficient bulbs. If you had a fixture or series of lights that took 3 bulbs, it would be better to have one device that converts AC to DC and then feeds all 3 LED lights direct current rather than having the converter built in to each bulb. And you could design fixtures that are better heat sinks than current ones too. But for the time being the focus is on coming up with bulbs that can fit existing installations.