A lot of people talk about underfloor heating these days as if its a new idea. Plenty of older cultures have been using similar technologies for hundreds or even thousands of years. Korea is particularly well known for its interesting history with heating homes. Check out what Wikipedia says:
In contrast to the eventual disappearance of the Roman underfloor hypocausts, underfloor heating has remained in use for millennia in Korea, where it is known as ondol. It is thought that the ondol system dates back to the Koguryo or Three Kingdoms (37 BC-AD 668) period when excess heat from stoves were used to warm homes.
Ondol continues to be a typical feature of the South Korean home, and is widely credited with making possible distinctively Korean customs such as removing one’s shoes upon entering a home and sitting on its floor. (The “sitting culture” brought about by ondol influenced the design of hanbok, the traditional Korean outfit; hanbok trousers are loose and have enough room for people to easily bend their knees and sit for long periods of time, and traditional shoes were also made to be easy to take off and put on compared to Western shoes.)
Definitely not a new concept but still a good one.