Natural Heating

This is how infrared heating works

You have been skiing. You are sitting on the patio in the sun. You are enjoying the enveloping warmth. At the same time, it’s freezing. This is possible thanks to the way in which the sun’s infrared rays work. When infrared rays touch a surface, energy is released in the form of heat. 

Infrared radiation is a natural and important source of heat transferral. An obvious example is the sun. The sun produces an enormous amount of energy through nuclear fission. The sun radiates this energy in various wavelengths including the form of ultra-violet rays, visible light and infrared radiation. After a journey through space of approximately 8 minutes at a speed of 1,080,000,000 km/h, the sun’s rays reach the earth’s surface. During the day, the earth’s surface is heated by the infrared part of the sun’s rays. At night, the earth cools off again by releasing the heat in the form of infrared radiation. This is a natural process which is not harmful to humans. In theory, every object with a temperature over the absolute zero point radiates heat rays. The intensity of the radiation increases as the vibration of the atoms in the object increases.

The shorter the wave lengths, the greater the energy content of the radiation. Infrared radiation consists of electromagnetic waves with a length of 0.75 to 1000 µm. When infrared rays fall onto a surface, the radiation energy is absorbed by surface atoms irrespective of the air temperature.

Heat transfer

According to the first law of thermodynamics, heat always flows from high to low temperature. The heat transfer from one site to another takes place by means of conductivity, convection or radiation. The driving force in this process is the temperature difference. The mechanisms for the transfer of heat, convection and radiation, can be applied to heating a space. In contrast with convection, heat transfer by means of radiation does not require an intermediate material. That is why, in the case of infrared radiation, the heat is released primarily to objects and secondarily to the ambient air.
In principle, infrared heating combines two separate heating mechanisms, namely heating as a result of radiation and heating as a consequence of the ‘insulating’ effect of the ambient air.

Radiation and insulation heat together

As soon as the infrared heating is turned on in a cold space of 0°C, for example, the radiation intensity is at a maximum and the air temperature minimal. As the air temperature gradually increases, the radiation intensity will gradually decrease. After a while, the air in the space will have reached a temperature of 18°C for example. The intensity of both the air temperature and the heating now remain constant. This means that an equilibrium has established itself in which a combination of both heating mechanisms provides a comfortable climate. This climate can be compared with a windchill temperature of approx. 20 °C. The advantage of this is that people feel comfortable more quickly at a relatively lower temperature than when air heating alone is used.