Ways To Increase Energy Efficiency In Drying Laundry

Dave Denkenberger

energy_efficient_ways_to_dry_laundryWhat’s The Most Energy Efficient Way To Dry That Load Of Towels? Is It Better To Dry Them For A Shorter Time On High Heat, Or Longer On Low? And Does It Make Much Difference?

I Was Part Of A Team At Ecova Who Tackled These Questions And Many More Related To Drying Laundry. Why? Because, Although The Questions May Seem Trivial, The Energy Impact Of Drying Is Not Trivial At All!

Add Up All The Energy Dollars We Spend Drying Laundry And You Get To A Very Big Number―$9 Billion, In Fact.  That’s How Much Americans Spend On Energy For Drying Laundry. And All Of That Drying Accounts For 40 Million Metric Tons Of CO2 Emissions Each Year.

Our Team Looked At Ways To Cut The Costs Of Drying Through Policy, Behavior And Technology Together. We Presented Our Findings At The 2014 ACEEE Summer Study On Energy Efficiency In Buildings. Here’s The Quick Version Of Our Findings.

Speed Matters – A Lot

Any Programs To Increase Energy Efficiency In Drying Must Consider Human Behavior. We’re Impatient. Ideally, We Like It When The Dryer Takes As Long As The Wash Cycle – And No Longer – So We Can Run Multiple Loads Easily. The Need For Speed Has Implications For Dryer Technology Choices As Well As Efficiency Standards:

  • Technologies:In Evaluating Different Improvements To Dryer Technology, The Research Indicates That There Is Often – But Not Always- A Trade-Off Between Energy Efficiency And Drying Time.
  • Standards:Efficiency Standards Should Account For Consumer Behavior. If A Dryer Offers Multiple Drying Modes (Slower And Efficient, Faster And Less Efficient), Both Should Be Tested And Reported To Give Consumers Realistic Expectations Of Energy Performance.
Are There Better Dryer Technologies?

We Looked At Several Different Dryer Technologies, Including Adaptations To Current Electric Dryers. Technology Does Hold Some Answers:

  • Air-To-Air Heat Exchanger Technology Added To Existing Electric Dryers Uses Waste Heat From The Drum To Increase The Temperature Of The Incoming Air. This Increased Efficiency (Up To 26 Percent) And Actually Reduced Drying Time (By 18 Percent) But Requires Hardware Modifications.
  • Slower Drying Using Existing Electric Dryers Can Save 25 Percent Of Energy, But More Than Doubles Drying Time. Slowing Does Not Improve Efficiency Of Gas Dryers When You Look At Source Energy (At The Power Plant).
  • Natural Gas Dryers Offer Improved Energy Efficiency With Faster Drying Times And Lower Incremental Costs. The Graph Below Illustrates The Energy Efficiency On The Y-Axis (Higher Is Better).

If You’re In An Area With High Electricity Prices, Natural Gas Dryers May Cost Less Than Using Electric Dryers Even If You Have To Extend Gas Lines. And If Your Laundry Room Has Natural Gas Hookups, Using A Natural Gas Dryer Makes Sense Even If Your Electricity Prices Are Low.

Overall, It’s Good News!
  • Near-Term Cost-Effective Technologies Can Reduce Energy Consumption By 20 To 30 Percent Without Lengthening Drying Times.
  • Offering Consumers The Option Of Trading Off Drying Time For Energy Savings Gives People More Control Over Their Energy Consumption.

For Utilities, Effective Energy Reduction Programs Could Encourage Natural Gas For Dryers:

  • Subsidizing Natural Gas Hookups For Laundry In New Construction.
  • Extending Natural Gas As A Retrofit For Existing Construction.

For more information about our research on dryers, download the entire Clothes Drying Time Technology and Policy research paper.

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