M.V. Diamanti, R. Paolini, M. Zinzi, M. Ormellese, M. Fiori, MP. Pedeferri
self-cleaning, titanium dioxide, environmental exposure, solar reflectance
This work focuses on the characterization of a self-cleaning and photocatalytic system for building façades, aimed at improving urban surfaces and the surrounding air quality, and decreasing energy consumption. Mortars containing anatase TiO2 nanopowders were characterized by photocatalysis tests and water absorption tests to underline the water uptake of such materials by capillary effects. Exposure tests in environmental conditions were then performed to evaluate the mortars self-cleaning attitude. Samples were exposed facing both north and south, with multiple inclinations, to have a wider understanding of the possible variation of self-cleaning efficiency on vertical surfaces, compared to horizontal, inclined and sheltered ones. These aspects were investigated by monitoring their spectral reflectance and its variation during 1 year of exposure. In spite of the non-optimal IR reflectivity, TiO2 containing materials are not only considered environmentally friendly for their photocatalytic ability and self-cleaning effect, but they may also be listed as “cooling materials”, given their ability to decrease surface temperature by a quick and easy evaporation of the water present on their surface. This effect was actually observed on tested specimens, and is considered to be of great help in decreasing the cooling demand of a structure, improving its energy efficiency.