Energy is wasted when conditioned air leaks out of ducts, and when unconditioned air leaks in. Leaky ducts also create indoor air quality problems by drawing attic, basement and crawl space air into the air supplied to the living space....
see ASBESTOS DUCTS, HVAC - where we cite research on these materials as well as advice on action plans when they're present in a building. Question: asbestos in Louisiana-Made Ceiling Tiles from 1971? (Aug 5, 2015) Melanie said: I need to find out if our ceiling tile contains asbestos...