WSU Extension Energy Program's Energy Experts provide this informative video on sealing your HVAC system ducts. This is an extremely cost-effective energy efficiency action that also improves indoor air quality. This video shows how ducts move air, where common leaks are, and shows how to fix them. The video is for building professionals or do-it-yourself homeowners. Even if you aren't planning to do the work yourself, this video shows why it is important to have it done.