Ancient Romans Had Heated Floors

Long before the invention of modern radiators, wealthy Romans enjoyed a level of comfort that would disappear for centuries. Their ingenious system, known as a hypocaust, was a marvel of engineering that functioned as a form of central heating. It began with a large furnace, or praefurnium, located outside or in a basement. The hot air and smoke from the fire were not vented directly outside but were instead channeled into a hollow space beneath the building’s main floor, which was raised up on a grid of short pillars.

This flow of hot gas would heat the tiles of the floor above, creating a pleasant, radiant warmth that spread evenly throughout the room. In more elaborate designs, the hot air was also directed up through hollow clay tiles embedded within the walls, heating the structure from all sides. While this technology was too expensive and labor-intensive for the average home, it was a standard feature in the grand public baths, or thermae, where it was used to maintain different temperatures in various pools and rooms. This ancient innovation was so effective that it provided a level of domestic comfort that would not be widely seen again until the 19th century.