Sky Temperature

The sky temperature is calculated as:

\[ T_{sky} \left((1-cc) \cdot 9.36 e^{-6} \cdot T_{e}^{6} + cc \cdot T_{d}^{4}\right)^{0.25} \tag{1} \]

where

cc is the cloud cover fraction, [0-1].

T_e is the ambient air temperature in degree Kelvin.

T_d is the dew point temperature of the ambient air in degree Kelvin.

Long wave radiative exchange from the exterior surfaces of the building is simulated to this temperature.