In order to accommodate the many people who used the baths everyday throughout the Empire, Roman Engineers devised a simple but effective way to keep things warm.
In the Roman baths, the warmer rooms (the tepidarium and the caldarium) had to be heated to certain temperatures and maintained in order to perform there given functions. How did the Romans achieve this? Through the magic of engineering and ingenuity.
The Romans developed a simple yet sophisticated heating method known as the hypocaust system. This hypocaust system worked by taking heat from the furnace room and allowing it to circulate underneath the floors and in the walls of the rooms, which would have created the heat or warmth needed. The level of heat needed would have been controlled by the amount of wood used in the furnace.
The caldarium would have been closest to the furnace, followed by the tepidarium. The floors of these rooms were raised during construction using pillars that created spaces through which the hot air could circulate. The tepidarium would have had these same spaces built into the walls so that the entire room would have been heated, creating the effect of a steam room.
Some Roman baths were heated more naturally. In the Roman provincial town located just beyond the River Avon, a local hot spring with a constant temperature of 118 degrees Fahrenheit was found. A city, aptly named Bath, was built there, which included the construction of a reservoir to control the 260,000 gallons of water that came to the surface each day. A large bath complex was built, of course, along with a temple and an altar. The springs at Bath became sacred, considered a place of healing, and drew visitors from throughout the Roman Empire.
