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Fans Offer Opportunities For Significant HVAC Energy Savings
February 27, 2014
Fans offer opportunities for significant HVAC energy savings. According to Michael Ivanovich, director of strategic energy initiatives for the Air Movement Control Association (AMCA) International, fans account for 80 percent of the so-called "parasitic" load — that is, HVAC loads other than prime movers like chillers and boilers. Starting in 2007, AMCA began developing a method of rating the efficiency of fans. This work led to fan efficiency gradients (FEGs) — a measurement of peak fan efficiency independent of the motor and drive.
Understanding the basic nature of these FEGs is important for savvy facility managers, principally because these efficiency grades, essentially an index of inherent aerodynamic quality, are referenced in last year’s International Green Construction Code (IGCC), and the 2013 update of ASHRAE 90.1.
More adoption of the AMCA fan standards is likely, says Ivanovich, as AMCA members begin to work with 2015 IECC code language and members of the ASHRAE 189.1 committee.
The gist of AMCA 205 is that:
- It applies only to fan types and sizes covered by the referenced test standards (some products, therefore, such as air curtains, are not covered).
- It defines a new industry metric, Fan Efficiency Grade (FEG), that will help engineers, owners/managers, contractors, and code officials have an indication of how efficient a fan is out of the box.
- It nudges system designers and contractors and owners who make purchasing decisions to select fans that will operate in the higher-efficient regions of the fan curve.
According to Tim Mathson, principal engineer for Greenheck and member of AMCA's air control task force, the last point is invaluable for fan selection among facility managers. He notes that ASHRAE 90.1 specifies a minimum FEG rating of 67.
"Since the FEG values are based on the peak total efficiency, and the actual fan efficiency varies significantly along a fan curve, there is also a requirement to select the fans within 15 percentage points of their peak total efficiency," Mathson says. "This selection requirement is a key point because it's the real mechanism that will save energy."