In modern construction, architects and engineers tend to design the building structure and mechanical systems independently. While a passive structure creates the outside facade and interior spaces, while energy-powered mechanical systems are primarily responsible for IAQ. Designers of vernacular architecture have known for centuries that this separation can be bridged if we let building materials join mechanical systems in creating healthy IAQ.
One unintended consequence of conven-tional mechanical heating is dry indoor air, especially pronounced in the heating season in cold climates. Without clear and universal-ly applied strategies for providing healthy lev-els of indoor water vapor, or relative humidity (rh), we have now created health and infec-tious disease problems from “Dry Building Syndrome” (DBS).