CALGreen embodied carbon moves to 5.409: the 2027 crosswalk
In July 2027 the reuse option stops being §5.105.2 and salvaged steel counts as zero GWP — here's the section-by-section map.
If you design nonresidential buildings — or DSA-SS schools and community colleges — at 50,000 square feet or greater, the CALGreen section you cite for embodied carbon is about to change numbers. Not the rules; the numbers. The 2025 Intervening Cycle's final express terms (BSC 03/25 for most projects, DSA-SS 04/25 for schools) went before the Building Standards Commission at its August 25–27, 2026 meeting and take effect July 1, 2027. The agencies describe the package as clarifying, conforming, and coordinating changes that do not materially alter the substance.
Here's the thing: "doesn't change the substance" still means every old citation on your sheet notes and spec sections is about to be wrong. (For why the whole 2027 cycle is thin, see our AB 130 supplement preview — it named the consolidation; this one gives you the crosswalk.)
Section 5.409 gets a new name and all three options
Today, embodied-carbon compliance is split across two sections. The building-reuse option lives in §5.105; the whole-building life-cycle assessment (WBLCA) and the product-GWP prescriptive path live in §5.409, "Life Cycle Assessment." The supplement pulls everything into one section and renames it "Embodied Carbon Reduction," with three labeled options. The crosswalk:
| Today — 2025 edition | July 1, 2027 supplement |
|---|---|
| §5.105.1 Scope (incl. 2× exception) | folded into §5.409.1 (§5.105.1 reserved) |
| §5.105.2 Reuse of existing building | §5.409.2 |
| §5.105.2.1 Verification | §5.409.2.1 |
| §5.409.1 Scope | §5.409.1 |
| §5.409.2 Whole building LCA | §5.409.4 |
| §5.409.2.1–.3 | §5.409.4.1–.3 |
| §5.409.3 Product GWP (prescriptive) | §5.409.3 |
| §5.409.3.1 | merged up into §5.409.3 |
| §5.409.3.2 Verification | §5.409.3.1 |
| Equation 5.409.3.1 | Exception 2, Equation 5.409.3 |
| Appendix A5.105.2 | A5.409.2 |
| Appendix A5.409.2 | A5.409.4 |
| Appendix A5.409.4 | A5.409.5 |
The compliance worksheets follow their sections: WS-3 (reuse), WS-4 (WBLCA), WS-5 (product GWP) and WS-9 get retitled and renumbered to match.
The scope line gets simpler — and so does the reuse bar
The §5.409.1 scope today still carries phased language: "Effective July 1, 2024 … 100,000 square feet or greater … Effective January 1, 2026, the combined floor area shall be 50,000 square feet or greater." The supplement drops the dated phase-in and states 50,000 square feet flat. The "two times the existing area" exception — the rule that bars an oversized addition from using the reuse option — moves from the old §5.105.1 into §5.409.1, so it now sits with the option it limits. The reuse test itself is unchanged: retain at least 45 percent of the existing structural elements and enclosure.
New lever: salvaged materials at a GWP of zero
This is the one newly spelled-out path. The prescriptive option today requires a Type III EPD for every permanently installed product in Table 5.409.3, and carries no salvaged-materials exception at all. The supplement adds one as Exception 1:
Previously used building materials or products that have been salvaged and then reused without substantial modification of their form are not required to have a Type III EPD and shall have a GWP of zero. Such materials shall be minimally processed only, such as cleaning, repairing, resurfacing and resizing.
That gives reclaimed steel, glass and similar products a documented, zero-carbon path through the prescriptive table — no EPD hunt for a beam that already exists. The limit is in the text: minimal processing only — cleaning, repairing, resurfacing, resizing. Reshape or remanufacture it and you are back to needing a declaration. (A standalone "salvaged material or product" definition was floated and then withdrawn; the concept survives inside this exception rather than as its own defined term.)
The old concrete carve-out becomes Exception 2: concrete mixes "may be considered as a weighted average" by volume per Equation 5.409.3, and industry-wide EPDs stay acceptable for it.
Verified against the 2025 CALGreen text now in effect: §5.409.2 requires the WBLCA baseline to match "similar size, function, complexity, type of construction, material specification, and location" — just "location," which the supplement changes to "geographic location" — and §5.409.3 carries no salvaged-materials exception today.
New signature duty: WS-5 now covers substitutions
The product-GWP verification worksheet, WS-5, is rewritten. Under the supplement the design professional of record attests that each product listed in Table 5.409.3 does not exceed its maximum GWP value — and adds a forward-looking commitment: "I will ensure during construction that any … material specification … substitution will be reviewed."
A mid-construction swap — a different concrete mix, rebar from another mill — is no longer only the contractor's submittal problem. Signing WS-5 now puts substitution review on the designer of record. Build that step into your submittal workflow before you stamp the sheet. The same alignment reaches the voluntary tiers: in Appendix A5, the Tier 2 LCA reuse exception now matches Tier 1 — the reference baseline "shall exclude the reused elements."
Before you re-letter your sheets
Three cautions. Projects permitted before July 1, 2027 are reviewed under the 2025 numbering — which edition applies turns on your application date. The separate flat-glass unit typo in Table 5.409.3 is being fixed in this same package — that is its own post. And because the agencies characterize all of this as non-substantive cleanup, confirm the final recorded section numbers with your jurisdiction before you rely on a cite.
What CrossBeam does with it
CrossBeam reads embodied-carbon submittals against the section numbers actually in force, so a reuse or product-GWP citation resolves correctly whether a project is reviewed under today's §5.105/§5.409 or the 2027 "Embodied Carbon Reduction" section. It flags a salvaged-materials claim for the zero-GWP path and surfaces the WS-5 substitution duty before it becomes a corrections letter.