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Cooling Tower Minimum Efficiency

Nonresidential HVAC

Codes and Standards Enhancement (CASE) Report

The Statewide CASE Team is requesting feedback on the 2019 Title 24, Part 6 Draft CASE Reports. The CASE Report presents pertinent information that supports the code change proposal. Please email feedback to You may also submit written comments to the Energy Commission. See the agenda for Energy Commission pre-rulemaking workshop (available here) for instructions on how to submit comments to the Energy Commission’s docket.

Draft CASE Report: Nonresidential Cooling Tower Efficiency

Measure Description

This CASE report proposes expanding the existing mandatory code language in Section 120.2(i), which requires economizer fault detection and diagnostics (FDD) for nonresidential packaged and split air handling (HVAC) systems greater than 54 kBtu/h (4.5 tons) in size using the ANSI/AHRI 340/360 test procedure with an air-side economizer, to also cover built-up handlers with these characteristics. As a result, the proposal will expand the requirement to cover all air handlers, both packaged and built-up, that are greater than 54 kBtu/h in size and with an air-side economizer.

FDD systems are automated systems designed to detect, diagnose, and report faults to improve economizer longevity and occupant comfort. Economizer FDD systems can be standalone, such as those onboard many packaged systems, or they can be integrated into a building direct digital control (DDC) systems via sequences of operations (SOO). This code change would require the detection and reporting of the following economizer faults listed in 120.2(i)7 for built-up systems as well as packaged systems:

  • Air temperature sensor failure/fault
  • Not economizing when it should
  • Economizing when it should not
  • Damper not modulating
  • Excess outdoor air

Request for Feedback

The Statewide Utility Team encourages participation in the CASE Report development process through the submission of data—both primary sources and references to existing data. We are requesting data from stakeholders on areas such as:

  • Availability of higher efficiency cooling towers
  • Real world performance of high efficiency cooling towers
  • Other information regarding energy savings, costs, market impacts, industry practices, and barriers to code compliance

The data will inform the energy savings estimates, cost-effectiveness analysis, compliance and enforcement, and market impacts that will be presented in CASE Reports.

Do you have feedback or data to share? Send us an email at

California Statewide Utility Codes and Standards Program

This program is funded by California utility customers and administered by Pacific Gas and Electric Company, Southern California Edison, San Diego Gas and Electric Company, Southern California Gas Company, Sacramento Municipal District, and Los Angeles Department of Water and Power in preparation for the California Energy Commission’s Codes and Standards Buildings Advocacy.