The Numbers Don’t Lie
Ahh, the afterglow of the shopping event of the year. This year we splurged on a new mattress for our guest bedroom. It was past time to replace the mattress of unknown age that I picked up at a second hand shop. Spending money on items between you and ground is something that I am less frugal about. Shoes, mattresses, and tires are just some of the things that I will gladly shell out a little extra on.
This year, Lowes’ Black Friday deal ended up sucking me in. They had a deal on LED lightbulbs for a buck a piece. I couldn’t believe how cheap that was, and yet I was a bit wary. Two years ago we shopped for TVs during Black Friday and from that experience I knew that manufacturers make special product models just for BF. These special productions runs usually cut corners and produce an inferior product. Two years ago, we ended up getting a name brand regular tv model on clearance for the same price as a BF generic. A decision I do not regret.
So color me unsurprised when I went into Lowes (on Monday, I’m not crazy enough to go on Friday) and saw that the expected life of these super cheap LEDs was only 2000 hours. Most LEDs have expected life 5-10 times as much for 2-3 times the price. Still, I loaded up a cart and swapped out most of the CFLs in our house.
Now for the math, was it the right decision?
Most of the CFLs replaced were 13 watts and had been installed about 3 years ago (~1/3 of expected life).
The LEDs are 9 watts and our electric rate $0.0912087/kWh (taken from our last utility bill).
I wanted to find out how many hours of life I needed to get from the LEDs to break even at $1. The difference between the CFLs and LEDs was .004 kWh.
2741 Hours
Damn, I screwed myself.
The good news is that if you are replacing a higher wattage bulb, say a 60 watt incandescent, the math works out favorably. In that case you only need to get 215 hours of life out of these cheapo LEDs to break even.
I guess I can console myself with the fact that the replaced CFLs were already 1/3 into their stated lives and CFLs contain mercury. Also, I did pass those CFLs onto neighbors who replaced incandescents. Yay for the world, boo for not doing the math beforehand.