Comfort systems work much better when they are located in the conditioned space of the home rather than in an unconditioned attic or crawl space. One option is framing-integrated comfort delivery which locates the heating and cooling ducts between floors. Builders are using more engineered framing products rather than dimensional lumber. Engineered products like open-web floor joists may provide adequate height and size openings for heating and cooling ducts, especially in high-performance homes with small space conditioning loads.