Thermal behaviour of a cool roof Aerogel-based: summer and autumn in-field campaign in a full-scale test-room

Passive radiative cooling material for building application show consolidated energy environmental and economic benefit, both to the users than community. Technological progress allows to develop new types of cool materials able, for instance, to emit infrared radiation into the space or to have a dynamic behaviour. There are also some paints based on Aerogel, marketed as insulating paints, which however, achieve a limited insulation, due to the extremely reduced thickness. The study of their spectral characteristics and behavior is limited in scientific literature and, their commercialization lacks independent scientific evidence and relies on non-standard detection methods. This paper aims to investigate, under real climatic conditions, the thermal performance of Aerogel-based cool roof, with a solar reflectance of 84% and a thermal emissivity of 90%. It is compared with a ceramic-based paint and a common finishing roof material of bituminous membrane. Since in literature there are mainly numerical/simulative studies or in-lab based, the analysis covers a whole summer and autumn season of continuous experimental campaign in a full-scale test-room, placed in Mediterranean climate. The application of ceramic paint determines an average surface temperature reduction of 9.0 °C during the day and 2.1 °C at night; while the Aerogel one 9.7 °C and 2.2 °C respectively. During the sunniest day the maximum surface temperature decreases of 25% and 28% for the ceramic and Aerogel coating respectively. This percentage increases on extremely hot day (-36% for both coatings) and decreases on windiest day (-20% for Ceramic coating and −24% for Aerogel coating).