By understanding the differences in code or standard editions, data center designers can know which version to use.
Learning objectives
- Understand how IECC and ASHRAE 90.1 work together regarding energy-efficient building design.
- Review the different editions of the standards to determine which compliance path should be used.
- Know that data center codes and standards are frequently shifting due to the vast changes in the industry.
IECC insights
- The variations between different versions of codes and standards should be carefully reviewed to ensure the proper edition is being followed.
- Because these codes differ, engineers should know which is being used to design a data center to meet energy efficiency needs.
Like the ASHRAE standards, the International Energy Conservation Code (IECC) has regular review periods and updates. Throughout the updated editions, ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings continues to be the backbone of the IECC. For example, the first requirement listed by the IECC in Chapter 4, Commercial Energy Efficiency, is to follow Standard 90.1.
When investigating how the IECC is written vis-à-vis ASHRAE Standard 90.4: Energy Standard for Data Centers, it is necessary to remember that ASHRAE 90.4 is not stand-alone but rather a compliance path for data centers extending from ASHRAE 90.1 (a normative reference for Standard 90.4).
Also, energy efficiency conformance requirements for data centers differ between the 2018, 2021 and 2024 editions of the IECC. These differences manifest in significantly divergent technical approaches for demonstrating conformity to the respective edition of IECC and are worth exploring.
Updates to IECC 2018
The 2018 edition of IECC does not include language on the use of ASHRAE 90.4. Also, unlike subsequent editions, data centers are not acknowledged or defined. IECC Chapter 4 requirements indicate three methods for attaining energy efficiency conformance, the first being ASHRAE 90.1.
Because the requirements for data center minimum energy efficiency come from Standard 90.1, this compliance path will differ depending on the edition of Standard 90.1 enforced by the authority having jurisdiction. As discussed in “ASHRAE 90.4 created to boost data center energy efficiency,” it wasn’t until the release of ASHRAE 90.1-2019 that ASHRAE provided an alternate compliance path for data center efficiency using Standard 90.4.
IECC 2021 edition
Regarding Standard 90.4, the 2021 edition of IECC bridges the gap between the 2018 and 2024 IECC editions. This is accomplished by providing Section C403.1 (building mechanical systems), which indicates that data centers are exempt from the requirements of sections C403.4 (heating and cooling system controls) and C403.5 (economizers).
Section C403.1.2 covers the requirements for mechanical system efficiency. Although this section indicates that data center systems shall comply with ASHRAE 90.4 Section 6, the mechanical load component (MLC) values are included in tables in the IECC. These tables replace the ones in Standard 90.4 Design MLC, Tables 6.2.1.1 and 6.2.1.2.
Although Standard 90.4 is not listed in the IECC Chapter 6, Referenced Standards, Standard 90.4-2016 must be the basis for the data center energy conservation requirements, as it is the only edition that uses design MLC. Design MLC was eliminated in the 2019 and 2022 editions of Standard 90.4, relying wholly on the annualized MLC metric.
The design and annualized MLC values are lower than those shown in Standard 90.4-2016, meaning the IECC requires higher efficiencies for the mechanical systems. By increasing efficiency requirements, the IECC-2021 significantly raised the bar on the ASHRAE requirements.
In addition to the mechanical requirements, the IECC also includes electrical system compliance. Section C405.1 indicates “transformers, uninterruptable power supplies, motors and electrical power processing equipment shall comply with section 8 of ASHRAE 90.4, in addition to IECC.”
IECC 2024 for data centers
If the 2021 edition of IECC is the bridge, the 2024 edition is the destination.The 2024 edition is the first IECC to fully address data center energy efficiency using ASHRAE 90.4-2022 as a compliance path and referenced standard. Section C403.1.2 consists of a single sentence, “Data center systems shall comply with Sections 6 and 8 of ASHRAE 2024.” This change eliminates the need for standalone tables or additional guidance in the code. It simplifies and streamlines the process and allows for consistent energy efficiency calculations for data centers.
There are also electrical requirements for data centers in the 2024 IECC. A completely new section, C405.9, Data centers and computer rooms, indicates that “electrical equipment in data centers and computer rooms shall comply with this section.” There are two new subsections, C405.9.1 “Data centers” and C405.9.2 “Computer rooms.” (The 2024 code differentiates between data centers and computer rooms). Subsection C405.9.1 is the same as Section 405.1 in the 2021 edition; it indicates compliance with Section 8 of ASHRAE 90.4.
With the advent of artificial intelligence and other breakthrough computing technology, data center power and cooling systems must be flexible, expandable and cost-effective, while using the least energy possible. Having codes and standards developed specifically for data center facilities creates a foundation for judging data center energy efficiency with a consistent, clear-cut and technically accurate approach.
