AIA California played a key role in the development of the first mandatory code requirements for reducing embodied carbon emissions, which took effect on July 1, 2024. These measures apply to public school projects 50,000 sq ft and over, and to large commercial building projects of 100,000 sq ft and larger, with the area threshold dropping to 50,000 sq ft and over on January 1, 2026.
Compliance methods included three paths that a design professional could select from, one of which is a Whole Building Lifecycle Assessment (WBLCA). Other compliance paths include prescriptive standards that reference Environmental Product Declarations, and a building reuse path.
For those project teams that elect to use the WBLCA approach, two models must be built and compared: a baseline model and a model of the proposed building.
In the upcoming intervening cycle, significant progress was made in precycle activities, which would have made available a variation of the WBLCA approach that referenced ‘embodied carbon emission budgets’. The advantage of this approach is that it saves time and money for both design professionals and the building official, as only one model needs to be prepared. The comparison is to a simple numeric value, rather than the output of a baseline model analysis.
The reason this ‘single model/carbon budget’ approach was not used in the original code development process from 2023 is that there was insufficient data at that time to establish embodied carbon budgets. Since then, data gathering and subsequent analysis have enabled the Carbon Leadership Forum to establish embodied carbon emission budgets that vary according to building use.
Since recently adopted provisions do not allow for substantive changes to occur in the intervening cycle, adding this embodied carbon budget option to the printed code cannot occur until the 2027 triennial code cycle (effective Jan 1, 2029). In the interim, by using the Alternative Means and Methods Request process, it’s possible that projects could take advantage of the simplicity and lower cost associated with the carbon budget, based on submitting an analysis to the local code official that demonstrated this approach is functionally equivalent to the approach that is in the current CALGreen. This use of ‘equivalent code performance’ is permitted by a process known as the Alternate Means and Methods approach, allowed by all California Codes and standards.
AIA California is considering commissioning a qualified subject matter expert to prepare a package of documents that would support an AMMR request as equivalent to the methods outlined in the CALGreen code. As part of the development of this template, AIACA would seek input from one or more urban jurisdiction building officials. We are seeking interested organizations to share in the cost of the development and support of this AMMR package.
If you are an architect interested in using the Embodied Carbon Budget Compliance approach to the CalGreen Embodied Carbon mandatory measures via the AMMR process, please let us know.
If you or your company would like to support creation or vetting of an AMMR template to allow use of Embodied Carbon Budgets let us know.
Send any notes of interest to Sarah Vasquez svasquez@aiacalifornia.org
AIA California played a key role in developing the first mandatory code requirements to reduce embodied carbon emissions, effective July 1, 2024. These requirements apply to:
Public school projects of 50,000 sq. ft. or more
Large commercial projects of 100,000 sq. ft. or more (dropping to 50,000 sq. ft. on January 1, 2026)
Design professionals can comply through three pathways:
Whole Building Life Cycle Assessment (WBLCA)
Prescriptive standards referencing Environmental Product Declarations
Building reuse
Projects using the WBLCA must prepare and compare two models: a baseline model and the proposed building.
During the most recent code cycle, work began on an alternative WBLCA method based on embodied carbon emission budgets. This approach requires only one model compared against a numeric budget, saving time and cost for both design professionals and building officials.
This option was not included in the 2023 code because sufficient data to set budgets was not yet available. Since then, the Carbon Leadership Forum has conducted extensive research and developed carbon budgets tailored to various building use types, resulting in equivalent performance.
Because substantive changes are not allowed mid-cycle due to recent legal changes, this carbon budget option cannot be formally added until conclusion of the 2027 triennial code cycle January 1, 2029. In the meantime, projects may pursue it through the Alternative Means and Methods Request (AMMR) process, demonstrating equivalency to CALGreen’s current requirements. All California codes allow such requests when equivalent performance can be shown.
AIA California is considering commissioning a subject matter expert to prepare an AMMR support package demonstrating equivalency with CalGreen for use of the simple carbon budget approach. Input from urban jurisdiction building officials would be sought in its development.
We are inviting organizations to partner with AIA California in funding and supporting development of this AMMR package which would permit use of the Embodied Carbon Budget approach, prior to the next triennial code cycle’s conclusion 1/1/ 2029.
