May 8, 2012

LED Bulbs

I've just been trying out some LED light bulbs and they seem to have progressed a great deal since the last time I played with them.  For recessed fixtures that have a narrow angle of lighting, they seem to be a pretty good deal.

Previous generations of LED light bulbs had problems:

  • Blueish color of light
  • Delay after turning on the wall switch
  • Wouldn't work with dimmer controls
  • Not as many lumens (brightness) as desired.
I've bought a couple different bulbs off of Amazon and tried them out.  I ended up really liking these ecoBrites:  No affiliation / kickbacks for me at all, I'm sure there are other great options out there too.

They seem to solve all of the above problems, though they do look a little bit different than regular bulbs if you look at the bulb when it's turned off.  

The key is to look for bulbs of a certain "color temperature".  The blue or "cool" colors are a higher temperature (around 4000-5000k) whereas the yellowish incandescents tend to be a warmer color around 2500-3000k.  CFLs are usually a higher temperature too though not usually blue, so they look very white.

My PG&E rates are tiered - 12.8c/kWh for the baseline, then it goes up to 14.6c/kWh for the next chunk and I'm actually bumping a small amount in to 30c/kWh rate lately.  So, my incremental cost of shaving off power usage is 30c/kWh initially and if I can get it down enough, probably 14.6c/kWh.

The above bulbs are 7W and replace 60W incandescents.  So, I'm saving  53W/h while these run.  They cost $39/bulb though.  Very conservatively, let's go with the 14.6c/kWh rate.  That's .7c/hr savings.  Assume I run each bulb for only 2 hrs per day.  To save $39, it'll take 6.9 yrs to breakeven.  That's the conservative number.

If you assume only that:
  • I'm replacing a bulb, so would have to pay $7 anyway, the breakeven is 5.6 years
  • I need to buy a new incandescent bulb every ~750 hrs, the breakeven is 4.4 years
  • the extra 53W of heat an incandescent bulb generates needs to be matched by at least 53W of air conditioning work (likely far more due to inefficiency), the breakeven is 3.4 years
  • I'm actually reducing my bill by the 30c/kWh rate, the breakeven is 3.4 years
  • If I'm using the bulb for 3 hrs / day, the breakeven is 4.6 years
If you assume all of the above, my breakeven becomes only 11 months.

In practice, the real story is probably somewhere in the middle.  I do need to buy incandescent replacements periodically, I sometimes need to use air conditioning, but certainly not always, and my savings is probably a mix between the 30c and 14.6c rates once all is said and done.  So maybe the breakeven is 2-3 years, so roughly a 26% return.  That still seems like a very good investment these days.