ASHRAE operates on a continuous maintenance cycle, regularly publishing addenda and complete revisions to keep pace with rapid technological advancements. Key focus areas in recent iterations include:
The next edition, Standard 90.4-2028, is currently under development, with its project committee's work beginning in 2025 and expected to continue into early 2028.
The standard provides:
The MLC measures the energy efficiency of the mechanical system (cooling). The 2022 standard updated the maximum allowed MLC to drive energy savings, particularly in air-side and water-side economization. Electrical Load Component (ELC)
In the rapidly evolving landscape of digital infrastructure, data centers have become the backbone of modern society. Yet, their energy consumption continues to rise sharply. In response, , Energy Standard for Data Centers and Telecommunications Facilities , has emerged as the definitive benchmark for designing energy-efficient, high-availability facilities. The latest update (2022) introduces critical changes that align with real-world operational data, climate-adaptive metrics, and the growing need for decarbonization. ashrae 904 pdf upd
of the design load to better align ELC with MLC methodologies. Heat Recovery Incentives
The first edition of ASHRAE 90.4 was published in 2016, with the goal of addressing the rapidly growing energy demand of data centers. The standard was developed in response to the increasing importance of data centers in modern computing and the need for sustainable and efficient operation. Since its initial publication, ASHRAE 90.4 has undergone several updates, with the most recent being the 2019 edition. ASHRAE operates on a continuous maintenance cycle, regularly
The ASHRAE Website is the only place to access official "read-only" versions of the standards and their free addenda. 4. Understanding MLC and ELC Compliance
The most current stable version as of 2025 is plus approved addenda. Major updates from earlier editions (2016, 2019) include: The 2022 standard updated the maximum allowed MLC