The current trend in radiant heating is towards underfloor heating, where radiator warm water is circulated under the entire floor of each room in a building. A network of pipes, tubing or heating cables is buried in the floor, and a gentle heat rises into the room. Because of the large area of this type of radiator, the floor only needs to be heated a few degrees above the desired room temperature, and as a result, convection is almost non-existent. These systems are reputed to have a high level of comfort, but are generally difficult to install into existing buildings. For best results, a floor covering that conducts heat well (such as tiles) should be used.

The hypocaust was a Roman heating system using a similar principle of operation.