Crawl spaces and basements are often sources of unwanted heat loss, moisture, odors, and polluted air. Solving these problems involves two different approaches – isolating the vented crawl space from the house by creating a thermal and air barrier at the house floor, or moving the thermal and pressure boundary to the foundation walls, creating a semi-conditioned crawl space. Isolating the crawl space can be more effective at reducing heat loss to the ground, but less effective at improving building durability. Conditioning them can solve some problems, but in low energy homes this strategy may incur a substantial energy penalty. While either strategy can be effective; all too often they both fall short. Success depends on understanding the complex interactions of heat, air, and moisture flow, combined with a healthy dose of caution, monitoring, and verification.
In the second of this two-part webinar, Graham Irwin and Gavin Healy expand on their highly rated session The 6th Side — House to Ground: Getting to Low Energy, Healthy Homes from ACI's June 2012 regional conference in Sacramento, California. Topics include the energy penalty of conditioning crawl spaces, migration of soil gases and pests from the ground through the crawl space to the home, code requirements, resistance and resilience to flooding, and the presence of mechanical equipment and utilities.