Radiation

In the night, warm surfaces directed to the sky, will be cooled by radiance. This effect can be described by the models for Radiation Transmission and Radiation Temperature.

The radiance is acting on the surface of the structure.

No shield or convective transmission coefficient (representing a shield) can be present the while the Radiation Transmission is active. A convective transmission coefficient representing the thin layer of air, expressed by a wind model, is accepted, because the radiance looks through the air layer. If an insulation is still to be included together with radiance, it must be modelled as a (thin) volume.

Heat transmission due to radiation is determined as:

Q = C_r (T⁴ - T_e⁴)

where

C_r is a radiation coefficient

T is the surface temperature of the structure (not the outer surface temperature of any insulation)

T_e is the external radiation temperature

The value of C_r is defined by the user in the model for the radiation transmission.

The value of T_e is defined by the user in the model for the radiation temperature.