Proposition of assessment methods of solar absorptance degradation for roofing materials in Brasil

• Grant number: 24/19537-9
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: May 01, 2025
• End date: September 30, 2028
• Field of knowledge: Applied Social Sciences - Architecture and Town Planning - Architecture and Urbanism Technology
• Principal Investigator: Kelen Almeida Dornelles
• Grantee: Marcela Macedo de Andrade
• Host Institution: Instituto de Arquitetura e Urbanismo de São Carlos (IAU). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 24/10060-5 - COATINGS FOR THE BUILDING ENVELOPE AND THE AGING ASSESSMENT OF ABSORPTANCE TO SOLAR RADIATION: proposition of a national method for accelerated aging practice, AP.R

Abstract

Roofs are the building elements that receive most solar thermal energy and their coating materials are exposed to natural weathering, which cause particles deposition and atmospheric pollutants on their surfaces. In tropical climates, quick particulate matter deposition and microorganisms' growth are observed, which cause greater changes in the solar reflectance and absorptance properties. Therefore, maintaining materials' visual appearance and their initial radiative properties (solar absorptance and thermal emittance) in relation to thermal performance are some of the problems observed. Furthermore, the empirical solution proposed by NBR 15.575-1 standard for aged solar absorptance property evaluation after three years of exposure does not consider the effects of dirt deposition. Thus, it is proposed to evaluate, in real environmental conditions in the field and simulated in the laboratory, different roofing materials aging. It is also intended to adjust empirical solution proposed by NBR 15.575-1 standard in order to consider the effects of particulate matter deposition in the evaluation of the aged materials' solar absorptance. Therefore, to evaluate different roofing materials aging typically used in Brazil, measurements of solar reflectance and thermal emittance will be performed on new and clean specimens as well as those degraded by the accelerated method proposed in ASTM D7897-18 standard and by natural weathering in the city of São Carlos (SP). As well for these radiative properties, materials' color parameters, surface roughness and temperature will also be evaluated in order to observe the variation of these parameters due to the degradation of the surface caused by the deposition and accumulation of particulate matter. Thus, it aims to propose an aqueous solution formulation of dirt suitable for the accelerated weathering test for Brazil roofing materials types and compatible with atmospheric conditions of São Carlos (SP).