Radiant heating, also known as, underfloor heating, claims its name from the place where the heating system is installed. The best and most energy efficient results are produced when radiant heating is installed prior to the installation of hardwood, tiles or stones. Underfloor heating system may be installed under existing floor as well, but the results are not the same. As compared to new construction, installation of radiant heating under existing flooring is less efficient because heat is required to pass through additional layer of subfloor. When installing radiant heating under existing flooring in 1st storey applications, ceiling access from a floor below must be provided.