Term: Radiation

The movement of energy by electromagnetic waves; can occur through a gas or a vacuum. One of the three modes of heat transfer (in addition to convection and conduction). At normal temperatures, radiation is in the infra-red region of the spectrum, whereas solar radiation is at visible wavelengths. Controlling radiation is important to both heat transfer through porous insulation and through windows, as well as playing a significant role in daylighting and solar heating.

Source: BSD-011: Thermal Control in Buildings