On July 16, 2026, ASHRAE announced it is restructuring Standard 90.1 to keep the standard focused purely on cost-justified energy efficiency, moving the optional operational carbon provisions added in the 2025 edition (Addenda M and N) into a new, separate companion publication. The core energy-efficiency requirements that drive most commercial energy codes stay exactly where they are.
ASHRAE's official announcement states that Standard 90.1 will keep its primary focus on energy efficiency and energy cost-justified requirements, while Addenda M and N, the optional operational greenhouse gas (GHG) provisions introduced in the 2025 edition, move out of the core standard and into a separate publication. ASHRAE President Sarah E. Maston framed the change as reinforcing a document that "has helped define energy-efficient commercial building design for more than 50 years," rather than replacing it.
Trade coverage from ACHR News and HPAC Engineering confirms the same structural change: the energy-efficiency core stays intact, and the carbon-reduction content becomes an optional, separate framework rather than disappearing.
The table below summarizes the split as ASHRAE has described it so far.
| Stays in Standard 90.1 (core) | Moves to the new companion publication |
|---|---|
| Cost-justified energy efficiency requirements for envelope, lighting, mechanical systems, and controls | Addenda M and N from the 2025 edition, covering optional operational greenhouse gas emissions |
| Status as the baseline energy standard referenced by most state and local energy codes | A template and framework for operational carbon reduction that jurisdictions can adopt separately |
| ASHRAE's consensus-based, ANSI-governed development process | Consideration of renewable energy availability as part of operational emissions accounting |
| Development through the 90.1 Standing Standard Project Committee's work plan | Use as a blueprint for jurisdictions building their own operational carbon codes |
According to ASHRAE's announcement, the restructuring responds to interest from states, cities, and large corporations that want clearer ways to pursue operational emissions reductions without complicating the energy-efficiency baseline that codes and inspectors already rely on. Keeping Addenda M and N inside 90.1 as optional provisions had started to blur the line between what is a mandatory, cost-justified energy requirement and what is a voluntary carbon goal. Separating the two lets each document do one job well.
ACHR News quotes building performance consultant Tarang Patel describing the move as "exactly the kind of structural clarity our industry needs," and noting that 90.1 works as a baseline "precisely because it's enforceable and cost-justified." That enforceability depends on language that inspectors, code officials, and commissioning providers can verify in the field, which is harder to do with provisions still being piloted.
ASHRAE has tied this restructuring to the 90.1 Standing Standard Project Committee's six-year work plan, spanning the 2028 and 2031 standard cycles. The committee, which includes 153 members and consultants plus contributing ASHRAE Technical Committees, will develop the new companion publication through ASHRAE's standard consensus process: economic justification, public review, and comment under ANSI procedures. No name or publication date for the companion document has been announced yet, and ASHRAE has not said whether it will take the form of a standard or a guideline.
For owners and design teams, the practical effect falls into three areas:
With no publication date set and development running through 2028-2031, the near-term action for owners is to make sure the compliance foundation under the current 90.1 energy-efficiency core is solid, since that foundation carries forward regardless of how the companion document develops. Commissioning and TAB data that accurately reflect as-built system performance give an owner a clean baseline to work from whether they later pursue an operational carbon framework or stay focused on energy-efficiency compliance alone. Functional performance testing tied to IECC commissioning requirements already produces much of the documentation that an operational carbon pathway would eventually ask for: verified equipment performance, control sequence confirmation, and measured airflow and water balance.
No. ASHRAE's announcement describes a restructuring of how Standard 90.1 is organized going forward, tied to the 2028 and 2031 development cycles. It does not change requirements in the current, already-adopted versions of 90.1 that local energy codes reference today.
Addenda M and N were optional provisions added to the 2025 edition of Standard 90.1 covering operational greenhouse gas emissions reduction. Under the July 2026 restructuring, these provisions move out of the core energy-efficiency standard and into a separate, dedicated publication.
The companion publication is described as an optional, cost-justified framework that jurisdictions and other users can adopt if they choose to pursue operational carbon reduction requirements. Standard 90.1 itself remains the baseline energy efficiency standard that most commercial energy codes already reference.
The announcement does not specify changes to how LEED, the IECC, or other programs reference Standard 90.1. Since 90.1's energy-efficiency core stays intact, programs built on that core are not described as needing structural changes. Programs that referenced the 2025 edition's Addenda M and N for carbon-related credit would need to watch for guidance on the new companion publication once it is developed.
Standard 90.1 compliance for mechanical systems depends on verifying that installed equipment, airflow, and control sequences match the design values used to demonstrate cost-justified energy performance. Testing, adjusting, and balancing data, combined with commissioning functional testing, is the verification step that confirms a building performs the way its energy model assumed. That link does not change under the restructuring.
No publication date has been set. The work is part of the 90.1 Standing Standard Project Committee's six-year work plan covering the 2028 and 2031 cycles, and development will follow ASHRAE's standard consensus process with public review and comment.
Whether your facility is tracking straightforward energy-efficiency compliance or weighing an eventual operational carbon framework, the verification work underneath both starts in the same place: accurate, documented system performance. Aero Performance Group's commissioning services cover third-party commissioning, retro-commissioning, monitoring-based commissioning, and IECC-specific commissioning, giving owners the functional testing and documentation that energy code compliance, and any future carbon framework, will continue to depend on.