We can draw 3 teachings out of that: the heat is thus transmitted “without contact”, indoor as outdoor, even if the surrounding air is cold (for exemple winter skiing). There is no need to heat the ambient air to feel the heat. The heat is felt by the human body when the radiation hits the skin.
Indeed, for a given wavelength (and depending on the efficiency of the heater), the “range” of the radiation will be more or less significant (or long). It is for this reason that we distinguish between the far infrared (or long) and other types of infrared, whose applications are different.
PS: the best far infrared heaters have a range between 4 and 5 meters around the heater (in all directions), whereas those emitting little infrared are limited to 50 cm (e.g. low-end radiants). It is then possible with this technology, and a proper positioning of the heater, to reach all the room zones to be heated.
3 different types of infrared for a multitude of applications
The IR-C, due to their qualities, do not penetrate deep into human skin (only a few millimeters). However, due to the heat absorption coefficients of the materials (absorption range between 2 and 20 µm), the far infrared is particularly well suited for the heating of buildings.
Illustration of the FIR Far Infrared Radiation for domestic heating / source: heatgood.com