Campi Flegrei,
Naples Gulf
In the volcanic region of Campi Flegrei, fumaroles (steam exhalations) were already used for heating the spas. The engineer and entrepreneur Gaio Sergio Orata realizes he could replicate that system with a double floor or crawl space. As a result, the combustion of wood inside communicating ovens produces hot air that circulates in this space.
The raised floor conquers
the Empire
In the following centuries, the system was improved and widely used in spas and luxurious villas in Rome. Brick pillars support the huge tiles that create the space under the floor where the heated air flows. In the hottest thermal environments (calidarium) the temperature reaches 60 degrees, requiring wooden clogs for walking.