Ductwork plays an integral role in the operation of any forced-air system. That may not be a bad thing on paper, but in practice, air ducts very often prove leaky, particularly when they run through uninsulated space or when gaps form at the joints between two sections. Believe it or not, in the process of transmitting heat throughout the home, ducts can lose enough of it to reduce the system's overall efficiency by 20 percent or more. No other heating system suffers the same fate. For instance, with radiant heat—the Warmboard system, for example—minimal heat loss translates into maximum savings. Meaning, you pay only for the heat you feel, and not for heat lost to a ductwork design flaw.