Radiant heating heats a building through radiant heat, rather than other conventional methods including convection heating. The technology has existed since the Roman use of Hypocaust heating. The heat energy is emitted from a warm element (floor, wall, overhead panel) and warms people and other objects in rooms rather than directly heating the air. The internal air temperature for radiant heated buildings may be lower than for a conventionally heated building to achieve the same level of body comfort (when adjusted so the perceived temperature is actually the same).

In the case of outdoor areas, the surrounding air is constantly moving, making conventional patio heaters (also known as “mushroom heaters”), which rely partly on convection heating, impractical. The reason being, that once you heat the outside air, it will blow away with air movement. Outdoor radiant heaters allow specific spaces within an outdoor area to be targeted, warming only the people and objects in their path.

– Wikipedia