Evaluating the cradle-to-gate environmental impact and cooling performance of advanced daytime radiative cooling materials to establish a comparative framework for a novel photonic meta-concrete.

Background: By the end of 2050, it is expected that 68% of the population will live in urban areas. A higher density of people living in cities generates an increased urban heat island. Radiative cooling (RC) materials are proposed as a key strategy to mitigate global warming and urban heating. The Horizon 2020 project MIRACLE aims at developing a new RC material based on conventional concrete. This paper presents a framework developed for comparing both the cradle-to-gate environmental impact and cooling potential of the newly developed photonic meta-concrete (or any other new RC material) with existing RC materials. The framework is applied to various RC materials using the generic Ecoinvent v3.6 database. The impact assessment method is in line with the Belgian life cycle assessment method for buildings and covers the 15 environmental impact categories of the EN15804:A2. The cooling performance is assessed by implementing the material spectral emissivity into a thermal model for Brussels and Madrid. Results: The study shows that the sputtering process contributes over 75% to the cradle-to-gate environmental impact of several RC materials, while materials produced without this process, have significantly lower impacts. The assessment of the cooling potential showed that convection heat gains make it difficult to create an all-year round cooling material. The comparison with a conventional building material, a concrete roof tile, hence shows great potential for these RC materials as heating gains during summer are significantly reduced. Analysing cooling performance alongside environmental impact, the study identified two RC materials, i.e. D6 and D10, as the most preferred in both Brussels and Madrid, considering their lower environmental impact and superior performance. Conclusions: The literature review revealed that a standardised way to assess and benchmark RC materials based on their cradle-to-gate environmental impact and cooling performance is lacking to date. This paper hence presents, for the first time, a method to compare RC materials considering these two characteristics. This method allows to identify the most competitive RC materials, which will serve in our study to benchmark the newly developed photonic meta-concrete. [ABSTRACT FROM AUTHOR]