Hydronic Radiant Floors

Under-floor heating distribution system that uses liquid-filled pipes to evenly distribute heat in the floor. The floor radiates heat into the space. It can be used with many kinds of floor, but is often embedded in several inches of concrete on the floor.

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 it can distribute sufficient heat even at a lower supply temperature of water, which can be more efficient and can use low-temperature renewable sources like geothermal, heat pumps, and solar hot water. Many people also like the feel of a warm floor. On the down side, 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 or 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.