Air Heated Radiant Floors

Radiant air heated floors is an forced-air heating system in which the heated air is passed through ducts installed in the floor, embedded in a substrate (typically concrete) that will conduct the heat. The warm air warms the floor, which then radiates heat into the living space.

If it's on the lowest level, make sure the heated floor is highly insulated underneath. A middle floor works even better because then heat radiated from the underside contributes to heating the next floor down.

In-floor heating has a large surface area so that it can distribute sufficient heat even at a relatively low supply temperature. This is relatively efficient and can use low-temperature renewable sources like geothermal, heat pumps, and solar-heated air. Many people also like the feel of a warm floor. On the downside, if the heated floor is on the lowest level, in contact with a cold basement or the ground, it needs to be very well insulated underneath. Otherwise, it will lose significant heat to the ground, decreasing energy efficiency.

Evidence of underfloor heating systems in homes goes back to the Neoglacial period, around 7,000 years ago, in Asia. These systems used the exhaust from fires, which was drafted through tunnels underneath the floor.