Radiant heating has been around since the inception of indoor heating. Around 1000 B.C., sometimes multiple hearths were used to heat the home. The idea was used that the closer to the fire the warmer the temperature, so if there were two hearths, it would warm the space (and the floor) more quickly. In addition, around this same time, there is evidence in Korea for a type of baked floors, showing that they had some form of in-floor heating for homes. Much later, in the first century A.D., there was the use of pipes to flow through walls or floor to radiate heated or cooled water throughout the air, altering the temperature in the room. The Turkish Baths of the Ottoman Empire are one evidence of this type of heating.
This method of radiant heat was used throughout history until present day, but it looked different according to the materials available to those in the area. Over time, the practice was modified and evolved depending on the availability and technology needed to make this type of heating possible.
Large radiators were stationed in one or two areas of homes and apartments to provide a source of heat to rooms. They were not prevalent, neither were they effective in quickly heating large spaces, especially when drafty. In the 50s in the US, baseboard heat became the norm in homes. The idea was to place the radiant heating along the outside of a room to more effectively heat the air in that room. In the mid-80s, in-floor radiant heat made a resurgence into homes all over the US, including Orange County. These floors use PEX piping that is sometimes used in repiping for homes. This form of heating is great because it uses the hot air to heat effectively, providing warm floors for bare feet and warmer ambient temperatures specific to heating zones.
Source: Healthy Heating