Sunday, May 29, 2011

Week # 18: Watt's Up? ... er... Down!

As we were researching refrigerators, I looked for a little device I had heard about that can easily measure the electricity usage and estimate costs of power for individual appliances. There are a few of them out there. We found one at Lowe's called the "Kill A Watt" EZ, model number P4460. It was $19, so I'll factor that in at the end. Click here to see the unit we purchased. Keep in mind there are similar units out there by other manufacturers, but this one seems to do everything I was looking for, and it was cheaper at Lowe's than any online price I've seen so far.

First, a little bit of background on our electric bill. There are some fees that are not dependent on usage, so I'll ignore those. State tax amounted to .13 cents for the month, not enough to make a difference, so I'll ignore that too. I'll focus just on the amounts our bill could be reduced by cutting back on our killowatt-hours (kwh) used.

Our bill is split into "tiers" which increase in cost as each dividing line is reached. For our residence, the "baseline" allowance in tier 1 is 267 kwh, which is charged at an average rate of .13 cents per kwh. Tier 2 gives us another 80 kwh, which we used up at .15 cents / kwh. Our usage topped out 103 kwhs into tier 3 during April, for which the charge is .24 cents / kwh.

Our total usage in April was 450 kwh, which was divided and charged at those three different rates. Reducing kwh will eliminate our most expensive kilowatt-hours first, so until we show our total bill creeping down into tier 2, I'll use .24 cents per kwh as the savings amount.

By the way, our bill shows there are as many as five tiers, so I suppose that means we're pretty average and not among the worst electricity hogs in the neighborhood. Still, there is certainly room for improvement, which starts by educating myself about how much each appliance actually costs to run.

Using the Kill A Watt meter is very easy. First, it asked me to set the rate we're paying (.24 cents/kwh for the moment) on the rate screen. Then, simply plug whichever appliance you want to measure into the meter, and plug the meter into the wall socket. Hit the reset button and leave it there for at least a few days for an accurate reading (since appliances often turn on and off based on need, the longer the time period measured, the more accurate the long term estimate). When you're done, the unit automatically tells you how much you're spending in electricity to run that unit for an hour, day, week, month, and year.

Of course, the first targets were the new and old refrigerators. Already, the Kill A Watt meter results are worthy of a blog entry. The old refrigerator, now removed from our grid, pulled 18.07 kwh in 134 hours of being connected to the meter. The new reefer pulled just 9.13 kwh in 146 hours time, well under half the prior usage. The annual cost comparison: $281 for the old, and $130 for the new. At a power savings of about $150 per year, the new unit will probably pay for itself over the time that we plan to keep it.

Checking to make sure tier 3 rates apply to the entire calculation: The estimates from our new toy are 1,181 in annual kwh for the old reefer and 548 kwh for the new. Subtracting and dividing by 12 to get a monthly number, the reduction should be about 53 kwh per month. That will not take us down to tier 2 rates, so the calculated savings at .24 cents / kwh should be pretty close.

I should see an Edison bill reduction of about $12 - $13 per month starting in June due to the new fridge, just in time to switch the air conditioner on. And of course, there's a pending application to increase rates this fall that I just noticed. Oh well... I'll worry about adjusting for that later if it makes a big difference.

One year's electricity cost saved by switching reefers: $281 - $130 = $151, minus $19 for the meter = $132

Total saved to date: $2,841.22

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