ISSN: 1309 - 3843 E-ISSN: 1307 - 7384
The most recent official version is , which was approved by the American National Standards Institute (ANSI) on January 31, 2024. Since its first publication in 2016, it has seen significant updates in 2019 and 2022, with a new version anticipated in 2025.
Compliance requires that data centers have permanent monitoring systems capable of measuring IT load, mechanical power, and electrical power. You cannot comply on paper alone; you must demonstrate operational compliance.
When searching for an , it is vital to source the document directly through official channels like the ASHRAE Bookstore or authorized distributors. Navigating data center design using outdated blog summaries or pirated, incomplete PDF clips introduces severe compliance and financial risks. Access to Climate Zone Tables
is calculated using the worst-case losses of each segment of the power chain to demonstrate a minimum level of electrically efficient design. Compliance is achieved when calculated values do not exceed those contained in the standard, with an alternative compliance path allowing tradeoffs between MLC and ELC. ashrae 90.4 pdf
The standard is continuously evolving. The latest released edition is , but a major new edition, 90.4-2025 , has recently been approved. The 2022 edition brought several important improvements over the 2019 version:
Both metrics are climate-dependent, with allowable thresholds varying across the 19 ASHRAE climate zones to account for geographic differences in cooling demands. Relation to Standard 90.1
The MLC allowance can be very tight for small facilities because overhead doesn't scale linearly. Solution: The standard allows a "simplified approach" using packaged equipment with listed efficiencies. The most recent official version is , which
The total hourly energy consumption of all cooling equipment (chillers, pumps, fans, cooling towers) divided by the design IT equipment load.
Unlike its predecessor, Standard 90.1 (Energy Standard for Buildings Except Low-Rise Residential Buildings), Standard 90.4 was specifically initiated to address the unique and energy-intensive load requirements of data centers. It was developed under the guiding principle that data centers are mission-critical facilities demanding careful attention to how efficiency requirements impact their availability and reliability.
To apply these regulations, perform calculations, or submit designs for compliance, you must reference the official documentation. The standard is updated on a regular cycle (e.g., the 2016, 2019, and 2022 editions) to reflect ongoing industry innovations. You cannot comply on paper alone; you must
(in Megawatts) you are designing for?
While 90.4 focuses on energy, it is designed to work alongside thermal recommendations, such as maintaining server inlet temperatures between 18°C and 27°C (64.4°F to 80.6°F) for optimal reliability. Operational Documentation:
: The 2024 IECC requires Section 8 (Electrical) compliance, while 2021 IECC only required Section 6 (Mechanical). A project that begins under one edition may need to be recalculated if local adoption changes mid-design.
Aligning your data center design with ASHRAE 90.4 offers several major advantages beyond simple code compliance:
