1.4 Basements/crawlspaces insulated, sealed and conditioned (Exceptions: see spec)

To comply with the EPA Indoor airPLUS and DOE Zero Energy Read Home programs, basements and crawlspaces should be insulated, sealed, and conditioned. There are exceptions to this requirement, including homes built in a 100-year flood zone, marine climate, or dry climate; homes built on a raised pier foundation with no walls; or homes built with a crawlspace that is sealed and has a capillary break and active dehumidification.

The following Solution Center guides provide more information: