With the possibility of harvesting the coldness of the atmosphere as an inexhaustible thermodynamic resource, passive radiative cooling technology is used for many applications such as refrigeration, renewable energy harvesting and dew condensation. However, in this study, we focus on dew harvesting as a new-researched area. This paper presents an energy balance modelling approach to predict the nightly water yield from meteorological data in semi-arid region (Mirleft, Southern Morocco). The proposed approach provides a comprehensive report on a thin film of calcite mineral ( ) that can be used as a selective shield allowing dew condensation during the night. The increased cooling of the exposed shield (condenser) was exploited using high IR emissivity of the calcite in the atmospheric window (8-13 microns). Indeed, Calcite functions as an excellent passive cooling material due to its strong emission within the atmospheric transparency window (8–13 μ m) and high reflection in the solar spectrum. The dew harvesting happens when the temperature of the shield is below the dew point temperature. The main goal of this paper was to estimate dew harvesting with high yield as a function of condenser temperature and thickness condenser.