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Nonresidential Air Distribution

Measure Description

This CASE Report will reduce the energy consumption of space conditioning fan systems in nonresidential buildings by both reducing static pressure in air ducts and adding a new metric that allows for more efficient fan selections. This includes three submeasures: high performance ducts/updates to fan power limits, improved fan efficiency metric, and expand duct leakage testing. Measures are modeled after standards developed, or in consideration, by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).

High performance ducts/updates to fan power limits

This submeasure is modeled after the measure entitled “High Performance Ducts to Reduce Static Pressure” in ASHRAE 1651-RP. This submeasure proposes to increase the stringency of prescriptive efficiency requirements for fan systems in nonresidential buildings by modifying the fan power limits. Higher fan system efficiency can be most readily achieved by reducing the static pressure in air duct systems, which is influenced by duct system design. The prescribed compliance path is to improve duct design and reducing design fan power would be an alternative compliance pathway.

Improved fan efficiency metric

This submeasure proposes to implement a new efficiency metric used for certain fans in the Title 24, Part 6 code language by transitioning from peak fan efficiency to the Fan Energy Index. More specifically, this measure proposes to adopt Addendum AO to Standard 90.1-2016. Fan Energy Index is an efficiency metric developed by the Air Movement and Control Association (AMCA), an organization that sets standards for commercial and industrial air movement equipment. Fan Energy Index addresses a longstanding problem in characterizing fan efficiency; a fan’s peak efficiency is often poorly correlated with its actual efficiency in typical operating conditions.

Expand Duct Leakage Testing

Expand  duct leakage testing requirements based on ASHRAE Standard 215-2018: Method of Test to Determine Leakage of Operating HVAC Air Distribution Systems (ANSI Approved). Some ideas are listed below.

  • Expand duct leakage requirements to more building applications.
  • Changes to 140.4 (l) to increase square footage requirements and to include multiple zone and variable volume systems.
  • Expand mandatory duct leakage requirement to multi-zone systems retrofits.
  • Revise mandatory requirements for duct leakage for renovations.

Provide Feedback

Participate in the Utility-Sponsored Stakeholder meeting for this topic on November 5, 2019 ! View the event here.

This measure description will be updated as research is developed to support the 2022 code cycle. For questions or suggestions, email Include the measure name in the subject line.


Relevant Documents

Measure proposals, supporting documents, and other outside references will be made public as they become available.


Give Us Your Feedback

The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

  • Use the form above to provide feedback on this measure.