CERTIFICATION AGENCY INTERPRETATION & GUIDANCE
Our NGBS Interpretations and Guidance documents provide clarifications on technical and verification issues related to NGBS Green certification
File Under: Chapter 9: Indoor Environmental Quality
The ICC 700 National Green Building Standard (NGBS) includes mandatory radon testing and mitigation requirements for buildings in EPA Radon Zone 1, as well as voluntary options in Zones 2 and 3 for certification points. The 2025 NGBS includes updates that increase the stringency of radon-related requirements compared to the 2020 NGBS. This document summarizes the technical requirements for radon testing and mitigation under both NGBS versions. It is important that architects, radon contractors, and other project team members know which NGBS version is being used, because the compliance requirements differ between the two versions.
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File Under: Chapter 9: Indoor Environmental Quality
For 902.3, buildings located in Zone 1 must have at least a passive radon system installed, and points are available when an active system is installed. Buildings located in Zones 2 and 3 earn optional points for both passive and active radon systems.
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File Under: Chapter 9: Indoor Environmental Quality
2020 NGBS Section 902.3.2 requires radon testing for buildings located in EPA-designated Radon Zone 1. If testing reveals radon concentrations above the EPA action level, 4.0 pCi/L, an active radon mitigation system must be installed. However, the NGBS does not require post-installation re-testing to verify that the mitigation system is effective.
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File Under: Chapter 9: Indoor Environmental Quality
A building is eligible to earn points toward certification for exhaust air flows that meet the listed NGBS minimum standards when testing is not feasible due to safety concerns and the Verifier can document compliance using prescriptive duct sizing.
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File Under: Chapter 9: Indoor Environmental Quality
2015 NGBS § 902.2.1 requires compliance with ASHRAE 62.2-2010. The 2015 NGBS includes the relevant 62.2 provisions in Appendix B.
2020 NGBS § 902.2 also requires compliance with ASHRAE 62.2-2010; the Consensus Committee did not revise the version of 62.2 even though there are two more recent versions (2013 and 2016) available.
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