Radiant heat is a form of energy that heats objects without heating the air in between. Heat is transmitted by invisible waves of light, also known as infra-red, that can be seen with special cameras able to record the image on film. An everyday example of the infra-red technology used in ou saunas is the warmth we experience from the sun but without the harmful rays.

Picture yourself enjoying a warm sunny day and a cloud passes over, obscuring the sun. You suddenly feel cooler because the cloud prevents the warming energy of the sun from reaching you, yet the temperature has not dropped thus the principle that radiant heat heats objects, not air.