Presidents Day weekend was a time for household activities. It's kind of humdrum because last weekend we treated ourselves to seeing The Importance of Being Earnest at the Paper Mill Playhouse, and the weekend before was an even bigger treat of spending two nights at a cozy inn in Vermont to celebrate my birthday.
So, with the whirring of the clothes dryer crowding out thoughts of Oscar Wilde, and of candle-lit dining rooms in the mountains, I started to settle back to the practical. Just how much, I wondered, does it cost to burn natural gas and churn through electricity to get our family clothes dry. The quick answer is about 25 cents for a 40-minute load. To see how we figured it out, read on. . . .
We have a gas dryer, so I had to consider how much natural gas is used to heat the air that dries the clothes, and how much electricity is needed to spin the drum that tumbles my daughter's growing collection of sweatshirts and flannel pants.
The power-usage label on the door frame of the dryer provided the starting point. It said our dryer uses 22,000 Btu an hour. A Btu is short for British Thermal Unit, and it's a global standard for measuring heat. A candle produces 1 Btu, so our dryer is harnessing the power of 22,000 candles! (Ah! Back to those candle-lit dining rooms!)
Next, I checked our utility bill for our gas rate. Our rate is quoted in Therms, another measure of heat output. A little more research showed that 1 Therm equals 100,000 Btu. So, if we're using 22,000 Btu an hour, that's 22 percent of a Therm.
The rest was pretty easy. Our utility bill said our gas rate was $1.526 per Therm. Multiplying that rate times 22 percent gave me an hourly gas rate of about 34 cents.
What I really wanted to know was how much it costs to dry one load of laundry. Our unit can dry a load in about 40 minutes. That's 2/3 of an hour, so 2/3 of 34 cents came out to 22.3 cents per load.
Almost done. We still have to add the cost of electricity. For that, we took our handy Kill-a-Watt electricity-usage meter (see earlier blog here) and plugged the dryer into it. My 40-minute load used about 2.8 cents of electricity.
The bottom line is that it costs about 25 cents to run our dryer for 40 minutes. Doing one load a day brings the cost to $1.76 a week, or $7.55 a month. Plenty of households run the dryer more than once a day, so the humble clothes dryer can end up being the second-most power hungry appliance in the house, right behind the refrigerator. (See this table for costs of running appliances).
If you have an all-electric dryer, the cost is even higher. I estimate that a dryer that uses 5,000 watts of electricity an hour costs about 57 cents for a 40-minute load.
I have a few more minutes to go before our next batch of clothes is dry. I think I'll use that time to think of Vermont.




Thanks for a very informative presentation! Thanks for sharing.
Posted by: crown moldings | March 11, 2011 at 03:23 AM
Thanks! This is a really good point that I didn't consider. I'll put it on my list of things to update.
Posted by: Janet | March 07, 2011 at 08:51 PM
Thanks! Very well-explained analysis and very useful to me as I'm trying to compare the cost of owning and operating a gas vs. electric clothes dryer. The only adjustment you should make is this: the gas dryer would use 22,000 Btus per hour if the burner ran ALL THE TIME, which it doesn't (it cycles on and off during the drying period, as the dryer thermostat demands). Most people who do this calculation assume the burner is on half the time. The same is true of the electric dryer - the heating element is on half the time. (Of course, the electric motor is running all the time on both dryers.) This will reduce the calculation of yearly energy usage by almost half. However, it won't change the energy use ratio of gas to electric dryers by very much.
Posted by: Steve Butzen | February 26, 2011 at 05:57 PM
Forgot the cost of the dryer.
Posted by: Kyle | January 09, 2011 at 09:33 PM
I posted your article to my myspace profile.
Regards
Tammy
Posted by: Professional Translation Services | November 09, 2009 at 09:33 AM
Gute Arbeit hier! Gute Inhalte.
Posted by: fussball | March 07, 2009 at 06:35 AM