I got up one night about a month ago and, looking out our bathroom window, I saw that our neighbor directly behind our house had illuminated his entire back yard with two powerful floodlights. Well, I thought, that's odd. Why have these lights on so late?
We're not living in a high-crime area, and there haven't been any reports of burglaries, so why the lights were on was a mystery. The next morning, I looked out and saw the lights were still on. And that's the way it went for more than a month, two lights on, 24 hours a day, seven days a week.
That got me thinking: What does it cost to leave the lights on? I decided to do a little research.
I took out our last electric bill and immediately felt intimidated. It was full of numbers, some going out to maybe 7 decimal places, and with all kinds of odd abbreviations like Kwh. Well, I had to start somewhere.
Fortunately, I found a really helpful Web site: It's called Saving Electricity, by a man named Michael Bluejay. Click here if you'd like to take a look.
It told me that the Kwh abbreviation is Kilowatt Hours. Probing further, I learned that a 100 Watt floodlight--and I assumed my neighbor was burning these--uses 100 watts in an hour, or 100 Watt Hours. There are 1,000 watts in a kilowatt, so a 100 Watt bulb, burning for one hour, uses one-tenth of a kilowatt, or 0.1 Kilowatt Hour.
Now it all became a little more clear than mud, but I forged ahead with my calculator and found I could make some pretty easy calculations.
The number on my bill with all the decimal places is the rate per Kilowatt Hour. Why they carry the number out to so many places is a mystery to me, but I found that if I simply round up to two places I get a calculation that equates to cents per Kilowatt Hour. In my part of New Jersey, the rate came out to about 15 cents per Kilowatt hour. Now we're getting somewhere! I had everything I needed to start calculating the cost of electricity.
Let's run through the steps. Two 100-Watt bulbs, burning all, day, every day, use 200 Watts every hour. In 24 hours, those bulbs will have used 4,800 Watt Hours, or 48 Kilowatt Hours (Kwh). Hmmm, at 15 cents per Kilowatt Hour, that comes to 72 cents a day.
Doesn't sound like much? Well, in a month, burning those two spotlights will cost my neighbor $21.60! I don't know about you, but that sounds like a lot of money for just two light bulbs. Just think about all the other lights and appliances you are using. I'll write more about that in future articles.
Apparently, our neighbor thought it was a lot of money, too, because right after we got our last electric bill, the lights went out. And they've stayed out!