Using the sky as heat sink: Climatic applicability of night-sky based natural cooling techniques in Europe

Climate change and environmental degradation are an existential threat faced by Europe and the rest of the world. To overcome these challenges, Europe requires a new growth strategy that transforms the Union into a modern economy that uses resources efficiently and competitively. The use of natural technology for cooling buildings is attracting attention due to the growing interest in energy and environmental conservation. Therefore, given the great cooling potential from using the sky as a heat sink and to promote the integration of nocturnal dissipation systems that use this environmental heat sink, the authors present a study to assess the potential of radiative water-based cooling systems that use a radiant panel or flat surface and water supplied to an air treatment unit through a storage tank. The method implemented in the study is based on the characterization of supply and demand and the subsequent linking of both through the natural cooling technique. This method presents the definition of performance indicators that allow to determine if the application of natural cooling techniques are of interest in a specific place. The method may be applied directly to assess the energy savings achieved by incorporating these systems into specific design and operating conditions, and inversely, by evaluating the design and operating systems required by the systems studied to obtain a given saving. The results of the study of their potential use in Europe show that the use of natural radiative and falling-film technology is of great interest. From the results obtained, it stands out that the integration of the falling-film system can provide savings of more than 60% in extremely hot regions and much greater in areas with less cooling needs. From the studies carried out, it is concluded that the integration of the falling-film means that practically no part of Europe requires an additional cooling system, making the continent passive in terms of cooling and facilitating the achievement of the objectives set by the European Union.