Special report: Fan efficiency guidelines
Structuring a fan efficiency requirement
Fan-efficiency codes and standards written around AMCA 205 define a minimum FEG and a sizing/selection window. Fan efficiency provisions can be further refined by specifying applicable sizes, types, and exemptions, as well as requirements for third-party certified FEGs and energy labels. The following are examples of where fan-efficiency requirements based on AMCA 205 have been adopted or proposed for model codes and standards for energy efficiency and green/high-performance construction.
IgCC-2012: The 2012 IgCC’s fan-efficiency provision includes a minimum FEG rating of 71 and sizing/selection window of 10 percentage points from peak static or total efficiency. It applies to stand-alone supply, return, and exhaust fans in buildings less than 25,000 sq ft.
This provision was based on AMCA 205-2010, which had a sizing/selection window of 10%, not 15%. AMCA 205-2010 also listed fan types that it does not cover, including air curtains and jet fans, because these types do not conform to the conditions supporting FEG calculations. AMCA will be proposing significant changes to this language for the 2016 version of this model code.
ASHRAE 90.1-2013: The significance of having a new fan efficiency requirement in ASHRAE 90.1 cannot be overstated. ASHRAE 90.1 is the benchmark state energy code for federal efficiency programs, many utility rebate programs, and state energy codes. It also is a compliance path for the model energy code, International Energy Conservation Code. ASHRAE 90.1 also forms the basis for the ASHRAE standard for high-performance (green) construction (Standard 189.1), and the International Association of Plumbing and Mechanical Officials (IAPMO) Green Supplement to the Uniform Mechanical Code and Uniform Plumbing Code.
Fan efficiency provisions in ASHRAE 90.1-2013 are written into the section that includes fan power limits. The fan power limits section encourages low-static-pressure air distribution systems, which save energy; however, it does not place appreciable constraints on efficient fan efficiency or right-sizing of fans.
ASHRAE 90.1-2013 specifies a minimum FEG rating of 67 and a sizing/selection window of 15 percentage points of the fan’s peak-total-efficiency rating (Figure 2).
The Standard 90.1 provision applies to fans with a nameplate hp rating > 5 hp and fan arrays that have an aggregate motor nameplate rating > 5 hp. The provision has a number of exemptions, including powered roof/wall ventilators, fans intended to operate only during emergencies, and fans in packaged equipment that has a third-party certification for air or energy performance. These exemptions will help engineers, contractors, building owners/operators, commissioning providers, and code officials learn how to implement fan efficiency requirements for the first time.
To learn more about the ASHRAE 90.1 fan efficiency requirement, read the article by John Cermak, PhD, and Michael Ivanovich in the April 2013 issue of ASHRAE Journal, which is available at www.amca.org/feg. To learn how fan power limits and fan efficiency grades interact during a fan selection, read the article by Michael Brendel, PhD, in the May 2013 issue of HPAC Engineering.
IECC-2015: The fan efficiency provisions in ASHRAE 90.1-2013 were proposed for IECC-2015, with a few refinements: FEG ratings would have to be “approved” and “labeled,” measures that are defined within the IECC, and were included to support compliance checking and enforcement:
APPROVED. Approval by the code official as a result of investigation and tests conducted by him or her, or by reason of accepted principles or tests by nationally recognized organizations.
LABELED. Equipment, materials or products to which have been affixed a label, seal, symbol or other identifying mark of a nationally recognized testing laboratory, inspection agency or other organization concerned with product evaluation that maintains periodic inspection of the production of the above-labeled items and whose labeling indicates either that the equipment, material or product meets identified standards or has been tested and found suitable for a specified purpose.
ASHRAE 189.1: AMCA has recently developed a “continuous maintenance proposal” that would insert a fan efficiency provision into ASHRAE 189.1. The provision is identical to the ASHRAE 90.1-2013 language, with the one exception being that the peak-total-fan-efficiency sizing/selection window is 10 percentage points instead of 15 percentage points. If the proposal passes committee votes, it could come out as an addendum for public peer review later in 2013.
U.S. Dept. of Energy: Development of the U.S. Dept. of Energy’s fan efficiency standard achieved a significant milestone with the publication of the Framework Document in the Federal Register on Feb. 1, 2013. The Framework Document presents DOE’s perspective of the fan market and the options it is considering for regulating commercial and industrial fans. AMCA International is collaborating with a number of industry stakeholders, including the American Council for an Energy Efficient Economy (ACEEE), the Appliance Standards Awareness Project, and the California public to jointly develop a proposal to DOE for the efficiency requirement.
Among the most significant differences a DOE standard will introduce is that a variety of fan types (DOE calls them classes) will be defined, and fan efficiency metrics and minimum energy efficiency performance requirements will be set for each class. Based on best-available information, a DOE requirement could be in place with enforcement between 2019 and 2020.