The US Department of Energy is enforcing a new testing protocol and a different metric for energy efficiency
The US Department of Energy has updated its testing and labeling standards for residential water heaters, replacing Energy Factor (EF) with a new metric called the Uniform Energy Factor (UEF).
Manufacturers say there’s nothing different about their water heaters, only the way the government requires performance data to be collected and reported.
Consumers shopping for a hot water heater by using the familiar yellow Energy Guides will see more detailed information than in the past.
Read more at http://www.greenbuildingadvisor.com/blogs/dept/green-building-news/water-heaters-get-new-performance-standard