Heat pump clothes dryers are significantly more energy efficient than conventional (ENERGY STAR®) electric resistance clothes dryers. The goal of this project was to determine whether heat pump clothes dryers offer non-energy benefits—specifically, reduced clothing wear and tear—that could help consumer adoption. Multiple machine types ran over 100 dryer cycles, using loads specifically chosen to reflect a variety of fabric and fiber types. This project did not conclusively find that heat pump clothes dryers cause less wear than conventional dryers. However, the project was able to show that they do not cause more wear than conventional ENERGY STAR dryers. This project was a co-funded effort lead by Northwest Energy Efficiency Alliance with Pacific Gas and Electric. Over drying is a common occurrence in clothes dryers which are not ENERGY STAR certified and that do not have good automatic termination controls. This report contains an addendum to the Clothing Wear and Tear of Heat Pump vs. Electric Resistance Clothes Dryers study that investigated relative wear impact of heat pump clothes dryers compared to ENERGY STAR dryers. In this project additional cycles tested whether over drying from a conventional dryer caused additional clothing wear. The cycles were set to replicate the equivalent over drying that would occur in a dryer which is not ENERGY STAR certified over the course of 1-2 years. The project did not find statistically significant incremental damage to clothing from moderate over drying.
