The American Society of Heating, Refrigeration and Air-Conditioning Engineers is seeking comment on revisions to its fan design standards.

The addendum would add a reference to the Air Movement and Control Association’s fan efficiency classifications to ASHRAE’s Standard 90.1, which deals with efficiency for most buildings. The change would require efficiency classifications based on letter grades.

“Currently, the standard only regulates fan power at the system design level,” said Ned Heminger, chairman of the Standard 90.1= mechanical subcommittee. “In other words, the amount of fan power allowed in a system is based on the system maximum airflow rate. However, the standard does not set requirements for the manufacturers of fans. As a result, there is a wide range of fan efficiencies available on the market.

“When the current prescriptive requirements were set for fan power, the fan efficiency chosen was achievable by most fans currently available at the time. Developing a fan efficiency metric that applies to the manufacturing of fans will encourage the advancement of efficient fan design,” Heminger added. As fan efficiency increases, fan power needs decrease. This allows the standard to improve on the fan power limits in the future. The proposed addendum has set the initial efficiency bar at a level that is achieved by most fans.”

The public has the chance to comment through July 10 at this website .