ISO 14934-2:2013 describes three methods for calibration of total hemispherical radiometers and total heat flux meters that are exposed to a well-defined radiation from a radiant heat source. The equipment is designed to minimize influences due to convective heat transfer during calibration. It is important to note that when the instruments are used in practice they measure a combination of radiant and convective heat transfers. The latter will depend on the design of the heat flux meter, the orientation, local temperature and flow conditions, and on the temperature of the cooling water.