Sunday, March 04, 2007

Cheap Compact Fluorescent Lamps

I've been using compact fluorescent lamps almost exclusively for ten years or more. I pay the extra price in the name of the energy efficiency that everyone claims for them. Even so, I've always been skeptical about claims of energy efficiency, especially when I start to think about the energy embedded in CFL lamps. Just looking at the two types of lamps (CFL and incandescent) I have to conclude that the energy it takes to assemble a CFL is many times greater than what it takes to make a standard incandescent bulb.

One of the reasons I've been skeptical about all this is because CFL's, in my experience, never seem to deliver the hours of service claimed by the manufacturers. I don't care how efficient a lamp may be, energy return on energy investment is compromised by poor durability (and greatly so, I think). I rather suspect that, all things considered, in the aggregate I've been using more, not less, energy by using CFLs. Who knows, though? In the summertime my air conditioner would work even harder if it had to deal with extra heat from incandescents. Maybe it's all a wash.

In the past couple of years I've taken to marking each CFL with the date it entered service in order to get a better sense of this. It's stupid, but when a CFL I've marked has failed, I generally just glanced at the date, bolstering my suspicion, and screwed in a replacement CFL.

This morning, though, I took the time to think about this a little bit.

A 26 watt (100 watt equivalent (yeah yeah, I know)) CFL that I had installed on November 9 2005 (480 days ago) failed in the bathroom. The bathroom has to be one of the more severe environments for a light bulb because of the number of on/off cycles as well as total running time. I thought about the usage pattern in that bathroom and figured that the lamp probably experienced about 15 on/off cycles per day, averaging 20 minutes or so of on time per cycle, which came to about 6 hours on per day. Over its cumulative service life of about 2880 hours, this bulb would have gone through about 75 kilowatt hours of energy, costing about $6 at 8 cents per kilowatt hour. It would have gone through about 7200 on/off cycles in the process.

Now, 2880 hours in nowhere near the lifetime claimed by CFL manufacturers. According to the EPA's Energy Star website, these things ought to last 6,000 hours or more.

Well, after a bit of looking around I found a document about durability testing of CFLs. The part that caught my eye was about stress testing, where they cycled CFLs on and off for the lamp's lifetime (five minutes on, five minutes off). What they found was that two manufacturers' lamps failed "very prematurely". Here's the relevant figure (click it for a bigger view):

I generally buy whatever CFLs Costco, Home Depot or Walmart are selling, which I assume are the cheapest things they can find. It wouldn't surprise me to find out that the lamps I buy are from the two sub-par manufacturers. I know the test cycle pattern doesn't match the usage of CFLs installed in my bathroom, but from the results of the test and my own experience, it seems reasonable to look for higher quality lamps. I'll see what the people at Lights of America have to say, and otherwise try to identify higher quality CFLs to buy. If I'm still here in a few years maybe I'll remember to post how the better lamps perform. On the other hand, maybe I'll revert to lower-wattage halogen incandescent bulbs for the bathroom. Apparently moisture can affect CFL's, so maybe I'll go with a higher-quality weatherproof CFL for the bathroom.

Should government ban incandescent bulbs, as is being done in Australia and as California is considering? Well, it seems to me highly likely that if we ban incandescents without, at the same time, banning sub-par CFLs like those in the graph above (presumably what I've been buying), it seems that such a ban would be worse, from a global perspective and considering embedded energy, than doing nothing.

1 comment:

jj mollo said...

Jane Galt has talked about her problem with CFLs at great length here, and here. The comments cover a lot of turf. I agree with you about the variability among brands. I am suspicious that we're getting cheated and lied to by these companies, because the CFLs are definitely not the same! I saw a Mythbusters episode that discussed the energy utilization of incandescants vs. CFLs, et al. They were trying to determine whether it mattered whether you turned them off and on when you left the room. It turns out that Some of them do fail early, but the energy saved by turning them off was way more than the cost of starting a light.

You also have to take into account the personal hassle of changing bulbs. Maybe Consumer Reports will come out and tell us which brand to buy. I have noticed that Sylvania CFLs produce a much more satisfactory light, but maybe it doesn't last. Also, leaving the bulbs on for a while improves the quality of the light. Halogen bulbs last longer than incandescant and are somewhat more efficient. I have used them where CFLs don't fit. They're quite small.

The real energy breakthrough is happening with LEDs. Mythbusters had one that looked really weird, but it used about 1% of the IC wattage. I have some LED flashlights that are very nice. Batteries last a long time. I haven't seen any of the IC replacement bulbs though.

Think about it this way though: We encourage innovation when we buy these things. The energy cost of creating them may be higher than for ICs, but it doesn't have to be fossil fuel. If they're made in Japan or France, then the power is probably nuclear. Personally, I really don't believe that the energy investment outweighs the life-time energy usage, but I suppose it might be true.