Kill‐A‐Watt results I

41PwTUFlsYL._SS500_Adding up all our Christmas lights, indoors and out, our holiday cheer burns an extra 643 watts of electricity when we are at full tilt, according to my Kill‐A‐Watt meter. Our pre‐lit tree alone clocks in at 286 W.

We only have two strands of LED lights, so I do not have much basis for comparison, but the LED strands do use remarkably less power. I have seen claims on boxes of 90% savings. That may or may not be pushing the truth, but it is clearly dramatic.

I am all for saving energy, but as with many new energy saving fads, claims about cost savings may be somewhat dubious. LED lights cost significantly more, and while they claim to last longer, the truth of these claims remains to be seen. From my observation, traditional lights have shown a correlation between purchase price and quality: better lights don’t flake out after the first couple of seasons. Only time will tell whether the same is true with the new technology. Throwing away old, inefficient lights and replacing them with new LED lights is (hopefully) obviously a waste of money and energy. Personally, I find it unlikely that LED light manufacturers are trying to sell us the last Christmas lights we’ll ever buy.

So, Clark Griswold, our 643 watts of Christmas lights, lit for 6 hours a day for the month of December, amount to 112 kWh of electricity use. That’s $12 in electricity cost, or less than the cost of one LED strand at this year’s prices.

Finding power hogs

41nMQyqE75L._SL500_AA280_My dad gave me a Kill‐A‐Watt meter for my birthday. It’s been interesting to see where our power hogs are. There are a lot of obvious ways to save power, so for me, using the Kill‐A‐Watt has been more of a fact finding mission. I have been surprised by devices using much more or less power than I had previously assumed. A product’s label is required to state its maximum power consumption, but that does not tell you the whole story of how much power it actually consumes under ordinary conditions. I will post some of the more interesting results in the future.

On first use, you can program the Kill‐A‐Watt with your electric rate. It makes sense to use your marginal rate, including fees and taxes for this, because you want to know what the cost is of using or not using this device. Our power company, Duke Energy, does not come out and directly state this, but it can be determined pretty easily by carefully looking at the details of the bill.rate details

Duke Energy charges a marginal rate of 6.7¢/kWh including fees and taxes during the winter months due to the way the rate tiers are defined. (Our power use is greatest in the winter because our house has an electric heat pump.) A snippet of a winter power bill is shown to the right. The last kWh was charged at $0.037794, but all the extra adjustments and fees, plus sales tax, bring the total to 6.7¢. In the summer, the marginal rate is 7.9¢/kWh. (I’ll save my opinion of why this sliding rate structure doesn’t make good sense for another post! Also, five significant figures in the rates?)

That said, I programmed the Kill‐A‐Watt for 10¢/kWh, for simplicity’s sake!

The U.S. Department of Energy maintains a list of average electricity costs by state. Indiana has the 13th‐cheapest power in the country, by my quick count.