Sparrow

Wade's Sparrow

Electric usage

I am often asked if driving an electric car has had any effect on our electric bills. We didn't really notice any difference. I don't have a separate electric meter for the Sparrow so we have to trust the meters in the car to tell us how much electricity the car uses.

According to the "E-meter" on the dash of the Sparrow I get 5 to 6 miles to the kWh. Given that my daily commute is 13 miles round trip, this is 2 or 3 kWH per day.

I average 220 miles per month in the Sparrow. Wind power here costs 7.8¢/kWh. This means the Sparrow adds about 40kWH or $3.00 to our monthly electric bill.

We had all of our utility bills since we moved to our current house and I was able to enter, and graph, all of our electric meter readings.

This was an interesting experiment. Our house has electric heat for the one room that used to be the attached garage. It also has air conditioning which we use between two weeks to two months of the year. It would seem that our electric use would be driven by the weather and be fairly random. The yearly averages have been much more regular than I expected.

The red line shows each of our monthly readings (these are actually daily averages multipled by 30). The green bars show the average monthly kWH usage for the year.

The steady rise in our electric usage is probably due to age. Our children are getting older, they can now reach the light switches and open the refridgerator themselves. Our appliances are getting older and perhaps less efficient. My wife and I are getting older and perhaps setting the thermostat differently.

The average annual increase in the monthly averages from 1997 to 2000 was 75 kWh (55, 72, and 97). Our average monthly kWh usage increased 127 kWh between 2001 and 2002. If we assume that our electric use would have gone up 75 kWh without buying the Sparrow, then the Sparrow is using about 52 kWh per month. This is pretty close to the calculation of 40 kWh using the Sparrow's meter.

The following events have also affected our electric use:

In January of 2001 we burned out our 3rd furnace motor. At that point we decided to stop leaving it running 24 hours a day and to use the "auto" mode when heating.
In January of 2002 I got my Sparrow and have been driving it almost everyday since.
In July of 2003 we added Ayumi, a Japanese exchange student, to our household for 11 months.
In March of 2005 we got a new "Energy Star" refrigerator.
In March of 2010 we replaced our two leaking gas hot water heaters with a single electric one. This choice is costing us about $25 per month in electricity, but saving us about $25 per month in natural gas.

Adding the electric car is the least noticable of these events.

We still don't have a clothesline.