What is Radiant Heat?

What is Radiant Heat?

Heat does not rise. Heat goes to cold. Hot air rises. With Step Warmfloor®, heat is kept where it is needed – at the floor. This type of heat is called radiant heat, which is the process in which energy is emitted, as particles or waves, by one body and transmitted through an intervening medium or space, then absorbed by another body.

When we stand on a cold floor or next to a cold wall, we feel cold. This has nothing to do with the air temperature and everything to do with the fact that heat is being lost from our bodies to warm up the cold objects around us. This heat loss is controlled with radiant heating.

Heat is transmitted / transferred from one point to another by:

  • Conduction: The transfer of heat between two parts of a stationary system caused by a temperature difference between the parts.
  • Convection: The transfer of heat by circulation or movement of the heated parts of liquid or gas.
  • Radiant: The process in which energy is emitted, as particles or waves, by one body and transmitted through an intervening medium or space, then absorbed by another body.

A convection system, like forced-air, relies on blowing warm air into the house. Since air does not maintain heat, the room temperature fluctuates as the system goes on and off. The concept of radiant heating is to heat cold objects within the room. Objects maintain heat, thereafter warming the air and giving an even and comfortable environment. A large area of mild surface temperatures, such as a warm floor, is capable of transferring as much heat as a small surface area, such as a radiator, at high surface temperatures. The even distribution of heat eliminates drafts and gives a pleasant comfort at a lower temperature, making the system more cost-effective.


Commonly used radiant floor heating systems are: hot water radiant floors (hydronic systems) and electric radiant floors (heating cables, flexible heating films and self-regulating heating elements).

  • Hydronic systems pump heated water from a boiler through tubing laid in a pattern underneath the floor. The water supplied to the system generally ranges from 85°F (29°C) to 140°F (60°C) and is controlled by thermostats to moderate the floor temperature. A cementitious material or an air gap is required to distribute evenly the heat.
  • Electric cables and flexible heating films convert electrical power into heat and require a thermal mass or an air gap to spread out the heat. Since the power generated is fixed, temperatures are controlled by on/off thermostats and floor sensors, creating differential temperature changes in the floor.
  • Self-regulating elements are made of a semi-conductive material, which acts as a sensor; the heat output increases as the temperature decreases and conversely, the heat output decreases as the temperature increases. The self-regulating element comes as a mat and can be placed directly under the floor covering because it cannot overheat. Learn more about STEP Warmfloor® self-regulating heating elements…

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