Letters: 600 Kilo-what?: Fall 2017

Fall 2017
A version of this article appears in the Fall 2017 issue of Home Energy Magazine.
Click here to read more letters.

I don't understand the featured article on the Home Energy website this month (“Measured Performance of Heat Pump Water Heaters,” HE online Summer ’17). It claims that the average electric consumption of clothes dryers is about 600 kWh per year. My wife and I have a vented Kenmore natural-gas clothes dryer that I have separately metered. From December 15, 2013, through January 26, 2017, the meter registered 26 ccf (hundred cubic feet), or about 8.7 ccf per year. That would equate to about 260 kWh per year.

What am I missing?

Andy Ruden
Philadelphia, Pennsylvania

Table 1. Summary Heat Pump Clothes Dryer Retrofits

Table 1. Summary Heat Pump Clothes Dryer Retrofits

Average Daily Dryer Load Profile Pre- and Post-HPCD (n=7)

Average Daily Dryer Load Profile Pre- and Post-HPCD (n=7)

Author Danny Parker replies:

There are 89 million residential clothes dryers in the United States, with 75% being electric models and 25% being natural-gas or propane. 

So electric clothes dryers outnumber natural gas dryers 3:1. We stand by those numbers—electric clothes dryers use at least 600 kWh per year. Some estimates run as high as 800 kWh per year.

Also, natural-gas dryers use some electricity for the rotating drum, the blower, and the gas ignition (a 400W glow bar). I have a gas dryer in my own house, and we measured it to use 0.72 kWh per load.

Finally a two-person household is a bit smaller than the average household, which consists of about 2.5 persons.

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