Vermont RBES 2023 Amendments: Section R408
Vermont quietly added an embodied‑carbon twist to its residential energy code. Section R408 puts insulation climate impacts on the scorecard, creating a simple path for manufacturers with product‑specific EPDs to help projects earn points. If your specs run through Vermont, this is a small rule with outsized commercial punch.
Section R408 in a nutshell
Section R408 of Vermont’s Residential Building Energy Standards adds an insulation embodied‑carbon calculation to the code’s points pathway. Teams summarize global warming potential per conditioned square foot using either default values or product‑specific EPDs as allowed in the rule’s Table 408.1.1 and Table 408.1.2 (Code of Vermont Rules, 2025).
Where it applies and when
The 2024 RBES update took effect for construction commenced on July 1, 2024, with statewide applicability to residential buildings three stories or less. Vermont later allowed projects that started on or after July 1, 2024 to comply with either the 2020 or 2024 RBES, per Executive Order 06‑25 announced in September 2025 (Efficiency Vermont, 2024) (AIA Vermont, 2026). The residential code foundation ties to the 2021 IECC as reflected on the U.S. DOE state profile (U.S. DOE BECP, 2024).
What project teams must calculate
R408 asks builders to total insulation quantities by location, note material type and R‑value, then compute a GWP intensity per conditioned square foot. The default path uses table values. The optimized path swaps in a Type III product‑specific EPD when it reports a lower GWP than the default. That swap moves the needle on the project points table and can be the tie‑breaker on code compliance.
Special rule for foams with blowing agents
The section calls out spray polyurethane foam and extruded polystyrene. For these, the EPD’s global warming potential must include A5 and B1 in addition to A1 to A3. That captures onsite application and blowing agent off‑gassing so numbers reflect reality, not wishful thinking. It is a precise requirement straight from the text, not a nice‑to‑have (Code of Vermont Rules, 2025).
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What EPD quality actually matters here
Accuracy beats romance. R408 expects cradle‑to‑gate values for most insulation. It expects cradle‑to‑installation and early use impacts for SPF and XPS. Program operator choice is flexible, but the declaration must be Type III, product‑specific, and list the stages used. If an internal worksheet or brochure omits stages or mixes units, it will not help a project earn points.
Why manufacturers should care
When a builder can claim lower GWP with your EPD, the project can earn code points without design gymnastics. That saves time and risk, which is exactly what specifiers value during permit season. Vermont’s residential code is mandatory statewide, which means every eligible home is in play for this advantage at bid time (U.S. DOE BECP, 2024).
How to prep your portfolio
We recommend a simple two‑workstream sprint. Product data readiness, then market enablement. It is quick to start and pays back fast.
- Map your insulation SKUs against current PCRs and confirm declared stages match R408 expectations, especially for SPF and XPS.
- Pull 12 months of production and utility data for the reference year. If a product is new, a prospective EPD is possible, then refined after a full year.
- Standardize units and surfaces so takeoffs translate cleanly to conditioned square footage.
- Package a one‑page summary per SKU with the EPD number, declared modules, and the GWP figure that aligns to the code’s calculation table.
Common pitfalls to avoid
Do not rely on generic brochures that only quote thermal performance. Do not forget to note which lifecycle stages your number covers. For foam products, skipping A5 or B1 will get flagged. And do not assume a 2019 declaration still matches the current PCR. If the PCR has rolled, plan your renewal on a calendar, not on hope. It is definately worth it.
The bottom line for insulation makers
Section R408 rewards manufacturers who bring clean, well‑documented EPDs to the table. Vermont homes still need R‑value, but now they also count carbon. If your numbers are ready, you help projects clear the bar with less friction, and that is the kind of quiet edge that wins specs.
Frequently Asked Questions
Does Section R408 apply to all new residential buildings in Vermont?
R408 is part of RBES, which applies statewide to residential buildings three stories or less. Projects commencing construction on July 1, 2024 or after can follow 2024 RBES, with an option per a 2025 executive order to comply with 2020 RBES instead. Confirm which path the project chooses. (Efficiency Vermont, 2024) (AIA Vermont, 2026) (U.S. DOE BECP, 2024).
What type of EPD qualifies under R408?
A Type III product‑specific EPD. Use A1–A3 values for most insulation. For SPF and XPS, include A5 and B1 as specified by the rule. Provide the declaration number on the project worksheet. (Code of Vermont Rules, 2025).
Can default table values be replaced with product‑specific data?
Yes. The rule allows substitution when the product‑specific EPD reports a lower GWP than the default. That substitution can improve the project’s points outcome under the code’s table. (Code of Vermont Rules, 2025).
About the Author
Eric works at the intersection of sustainability, regulation, and business strategy, helping manufacturers navigate the evolving landscape of EPDs and LCAs. Having spoken with hundreds of teams across North America, brings a deep understanding of what drives ROI, what regulators are asking for, and how companies can stay ahead with smart, scalable approaches to environmental reporting.
