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About This Item


Full Description

ANSI/ASHRAE Standard 90.4 offers a framework for the energy-efficient design of data centers, with special consideration given to their unique load requirements as compared to other buildings. Standard 90.4 was developed under the guiding principle that data centers are mission-critical facilities, and careful attention must be paid to the potential impacts made by the standard’s requirements. This philosophy continues to guide successive editions, while acknowledging energy-efficiency breakthroughs in the industry.

Standard 90.4 establishes the minimum energy efficiency requirements of data centers for design, construction, and operation and maintenance, and use of on-site or off-site renewable energy resources. The standard was developed to be code-intended, similar to Standard 90.1, and Standard 90.4 references Standard 90.1 for building envelope, service water heating, lighting, and other equipment criteria.

The newly revised 2022 edition of the standard arrives with significant changes:

  • Additional options for mechanical load component calculations
  • A further reduction to the maximum ELC values required for compliance
  • The elimination of incoming service segment from ELC calculation in recognition that designers must already account for public utility transformers and feeders in most projects
  • New ELC segment calculation breakpoints of 25%, 50%, 75%, and 100% design load to make ELC and MLC congruent
  • A new methodology for applying a credit to combined MLC and ELC for the deployment of onsite renewable energy
  • Specific language to give credit for recovered heat shared with non-data-center spaces

Document History

  1. ASHRAE 90.4-2022


    Standard 90.4-2022 -- Energy Standard for Data Centers (ANSI Approved)

    • Most Recent
  2. ASHRAE 90.4-2019

    Standard 90.4-2019 -- Energy Standard for Data Centers- (ANSI Approved)

    • Historical Version
  3. ASHRAE 90.4-2016

    Standard 90.4-2016 -- Energy Standard for Data Centers (ANSI Approved)

    • Historical Version

Amendments, rulings, supplements, and errata

  1. ASHRAE 90.4-2022 Errata Sheet (September 14, 2023)


    Errata Sheet (September 14, 2023) to Standard 90.4-2022 -- Energy Standard for Data Centers (ANSI Approved)