ASHRAE 90.4-2025 ✓ Most Recent

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 2025 edition of the standard includes the following significant changes:

• An expanded purpose statement allowing for the future inclusion of resources and considerations beyond direct energy use that contribute to data center sustainability and decarbonization, such as GHG emissions, environmental impact, water consumption, etc.
• Updated definitions of process heat and ventilation to support the regulation of process heat and process ventilation
• Refinements to UPS segment and ELC calculations to clarify that UPS efficiency must be based on the total available capacity of the UPS, including its redundant capacity