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Radiant heat vs. convection heat

Although they are based on two very different physical processes, radiant heat and convection heat are both commonly used in modern heating systems. To offer a better understanding of each heating method and when to use which heat, we’ve drawn up this comparison explaining the various possibilities.
Radiant heat compared to convection heat

Convection heat

Convection heating has been the most common form of heating for a long time. A typical convection heater, such as a horizontal panel radiator, heats the air in a room with a mixture of about 65% convection heat and 35% radiant heat. Cold air drops and warms up as it comes into contact with the radiator. It then rises, making space for more cold air that gets heated in turn. This is why you’ll often find radiators installed below windows, so that they can immediately capture any cold drafts coming in, heat the air and disperse it into the room. Air, however, is a poor heat conductor, so convection heaters work rather slowly and it can take a while for the air to warm and the set temperature to be reached.

Radiant heat

Whereas convection heat is a thermodynamic process, radiant heating relies on quantum dynamics. Similar to solar radiation that heats up the objects and surfaces it touches, a radiant heating system, such as an underfloor heating system or ceiling heating panels, heats all the objects, people and surfaces in a room with about 90% radiation heat and 10% convection heat. These, in turn, transfer their heat to the room. Since radiant heat is more direct, you feel the warmth quicker. The air in the room, however, doesn’t absorb the heat rays and therefore stays cooler.

Heat distribution

Since convection heat relies on the movement of air, it can be difficult to get even temperatures throughout the room. Hot air rises, while cold air drops to the floor. So, with convection heaters you’ll find that avoiding cold spots can sometimes be a bit of a challenge. Radiation heat, on the other hand, is distributed more evenly into the interior and causes less changes to the surrounding air temperature.

When to choose radiant heat or convection heat?

Convection heaters, such as the Thermopanel V4, Narbonne or Compact radiator, remain an efficient heating solution for both new buildings and renovation projects. They easily fit into a home or office décor and offer a very versatile way of heating. When using radiators in combination with a low temperature heating system, the required larger heating surface will decrease the convection heat and increase the share of radiant heat.

As convection heat moves the air in a room, it causes dust particles to swirl around. This can create the perception of dry air and possibly exacerbate allergies. This is partly why in hygiene-sensitive environments such as hospitals and care facilities, there is generally a preference for a radiant heat system such as the Heliuz panel system. This is more hygienic as it doesn’t spread dust around the room. Moreover, hospitals often have various instruments or healthcare installations mounted to the wall, which leaves limited space for a conventional radiator. In such cases the ceiling is a good place to integrate radiant heating and cooling.

Energy-efficient heating

Although a radiant heat system can be more expensive to install, it offers a very energy-efficient way of heating. This has to do with the low air exchange rate. Air exchange is a must for hygiene reasons. With convection heating you have to reheat the fresh air that enters the room to reach the set temperature again. Radiation heat warms up the walls and objects in the room rather than the air, so only a very small amount of energy is required to top up the room temperature after an air exchange.

If you have any questions about radiant heat and convection heat or wonder which heating solution will offer optimal indoor climate comfort for your current or future building project, don’t hesitate to get in touch. We will gladly help you customise your heating solution.