News & Events


The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has released the revised version of its energy standard for data centers.

The ANSI/ASHRAE Standard 90.4-2019 establishes the minimum energy-efficiency requirements for the design and operation of data centers.

The Standard 90.4 applies to data centers with a conditioned floor area greater than 20W/ft2 and IT equipment loads greater than 10KW. It also contains specific requirements for mechanical and electrical systems installed in new data centers or in data center additions/alterations that require new mechanical or electrical systems.

“Standard 90.4 was developed under the guiding principle that data centers are mission-critical facilities that demand careful attention to the potential impact of requirements,” said Richard Zbin, chairman of the Standard 90.4 committee.

“The updated standard enables operators and designers to use the latest and most effective equipment and techniques to achieve energy efficiency in data centers, while avoiding potential reliability issues.”

During the publication of the Standard 90.4 in 2016, the society explained that the energy standard is a performance-based design standard that offers the design components for mechanical load (MLC) and electrical loss (ELC). Calculations of the MLC and ELC are made and then compared to the maximum allowable values shown in the standard based on climate zones. Compliance with Standard 90.4 is achieved when the calculated values do not exceed the values contained in the standard. An alternative compliance path is provided that allows tradeoffs between the MLC and ELC.

The now revised version of the Standard 90.4 features the following;

  • Renumbered sections and revised wording align more closely with that of Standard 90.1.
  • Mechanical efficiency requirements are based entirely on yearly energy calculations and no longer include a power calculation option. Included table values are also aligned with the newest ASHRAE Climate Zones.
  • Significant improvements are made to uninterruptible power supply (UPS) technology. Mechanical and electrical infrastructure elements are addressed. Updated UPS segment tables reflect available hardware, and average outputs are also included.

According to ASHRAE, this energy standard for data centers showcases a performance based approach that is more flexible and accommodates innovative changes that rapidly occur in design, construction and operations within the industry.