Important Innovations: Hypocaust
Central heating is not a product of the 18th or 19th Century, as you may expect. Historians tell us that central heating was invented by the Romans in the 1st Century B.C. Heating of Roman private homes and public bath houses was accomplished by an underfloor heating system called hypocaust (Latin: hypocaustum).
Heat from a wood burning furnace was drawn under a raised floor supported by 2′-3′ tall pillars, thereby heating the room by heating radiating from the warm floor surface. Ceramic flues were build inside the walls to allow polluted warm air to exhaust through chimneys. These flues heated the walls transferring additional heat into the room. Temperature variation was achieved by locating rooms requiring more heat closer to the furnace and by continuously building up the furnace heat with additional wood.
Hot water pools, spas and saunas were often placed inside of these rooms. Water was heated by the furnace and gravity fed into the spa or pool. Ruins of hypocausts are found throughout Europe.
by John Fitzpatrick, a residential architect in Austin, Texas, and president of Fitzpatrick Architects. Featured drawing by Fitzpatrick Architects