Radiative sky cooling is a result of heat loss by longwave emission toward the sky. For the use in hheat transfer applications and calculations, researchers have studied and proposed different sky effective temperature models and correlations since the early 1900s. One such use is for calculating a building's cooling loads, where the sky longwave exchange is an effective building energy balance element. Several factors influence the effective sky temperature, including location, ambient temperature, dew point temperature, and cloud cover. As a result, knowledge of current sky temperature models is important to better understand and characterize building heat transfer interactions, ie, sky longwave radiative exchange. Therefore, the objective of this paper is to provide a comprehensive survey of existing sky temperature models from the available literature. The role of sky radiative exchange within building energy calculation is demonstrated. Moreover, the models are categorized by data input requirements and wideranging results are shown under various climate conditions. Finally, for selected models, a comparison of hourly sky radiation exchange from a horizontal surface is provided.