Radiant heat is heat which radiates out from an element, warming objects rather than the air. An example of this heat that many people may be familiar with is the heat which comes off an electric element on a stove. People often use the term “radiant heat” to describe a particular type of home heating system which has been in use for thousands of years.
When a home is heated with radiant heat, rather than heating air and encouraging it to circulate, radiant elements are installed in the floor, walls, or ceiling. The elements heat the surrounding surface, which in turn radiates heat out into the room. Some convection is also involved in a radiant heating system, as the air in the room naturally warms and starts to flow, promoting the spread of heat.
There are a number of advantages to using radiant heat. This type of heat tends to be more efficient, especially since it can be installed in a number of creative ways. It is also silent, requiring no fans or blowers to function. It can be safer, reducing the risk of fire and making children safer, as there are no exposed heated elements for them to burn themselves on.
Classically, radiant heat is accomplished under the floor. In regions of the world with natural hot springs and sources of geothermal power, like China, Italy, and Iceland, people have been building their homes over hot springs to create natural radiant heat for quite some time. In the modern era, people can also heat their flooring with tubes of hot water, electrical elements, and other techniques. Hot water heat is especially appealing for some people, because the water can be heated with solar energy, and used for bathing and showering once it has passed under the floor.
For radiant heat to work, it helps to have a flooring which will conduct heat well. Stone, tile, concrete, and glass flooring can also be very suitable for this type of heating. These materials will also absorb heat from the sun during the day, supplementing the radiant heating system. Materials like wood and carpeting tend to insulate the floor, reducing the amount of heat transfer and making the heating system less effective.
People can also install radiant elements in walls or ceilings, classically using metal or ceramic plates to spread the heat out. The advantage of installing in the floor is that heat rises, so as the air near the floor warms up, it will drift upwards and heat the room. By contrast, installing in the ceiling will make the attic and roof toasty, but do little for the room.