The direct transfer of heat energy to the environment occurs by radiation and conduction . Radiative transfer occurs between the body surface and all other sources of radiant energy. Conductive transfer occurs by direct contact between the body surface and other materials including air, water or ground. Both radiative and conductive heat transfer move heat energy between the body surface and some other material. Convection augments conductive heat transfer.
Conduction occurs between two materials in direct contact.
Conduction will stop when the two materials in contact reach thermal equilibrium. Convection prevents thermal equilibrium developing by constantly replacing at least one of the materials. For example, convection replaces air warmed by conduction while in contact with the skin surface with air not yet warmed so heat transfer can continue. If the body surface is warmer than the environment, the body will lose energy to the environment. Maintenance of body temperature requires that the amount of heat energy in the body remains constant.