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Publication . Article . 2014

Effect of ageing on solar spectral reflectance of roofing membranes: Natural exposure in Roma and Milano and the impact on the energy needs of commercial buildings

Riccardo Paolini; Michele Zinzi; Tiziana Poli; Emiliano Carnielo; Andrea Giovanni Mainini;
Open Access
Published: 01 Dec 2014
Country: Italy
Highly reflective roofs, widely known as cool roofs, can reduce peak surface temperatures and the energyrequired to cool buildings, mitigate urban microclimates, and offset CO However, weathering, soiling,and biological growth affect their solar reflectance. In this study, the solar spectral reflectances of 12roofing membranes were measured before the exposure and after 3, 6, 12, 18, and 24 months of naturalageing in Roma and Milano, Italy. The membranes with an initial solar reflectance greater than 0.80, forexample, decreased in reflectance by 0.14 in Roma and 0.22 in Milano after two years. Then, for a typicalhighly insulated commercial building, the annual cooling load savings were calculated to be reduced by4.1-7.1 MJ m-2y-1per 0.1 loss in reflectance. When the buildings are non-insulated, the savings reductionis 58-71 MJ m-2y-1in Milano and 70-84 MJ m-2y-1in Roma. Ageing yielded a reduction of the coolingload savings that could be achieved with a new white membrane of 14-23% in Roma and of 20-34% inMilano. Moreover, in Milano, an aged, white, highly insulated roof, which has a solar reflectance of 0.56,may reach a surface temperature 16°C higher than a new roof, which has a solar reflectance of 0.80. 2014 Elsevier B.V. All rights reserved.
Authors: Paolini R., Zinzi M., Poli T., Carnielo E., Mainini A.G.
Zinzi, M.
Subjects by Vocabulary

Microsoft Academic Graph classification: Building envelope Cooling load Reflective surfaces Roof Engineering business.industry business Microclimate Reflectivity Atmospheric sciences Optics Solar reflectance Biological growth


Cool roof;Solar reflectance;Building envelope;Building energy need;Ageing;UV-Vis-NIR;Soiling;Natural exposure, Cool roof, Solar reflectance, Building envelope, Building energy need, Ageing, UV-Vis-NIR, Soiling, Natural exposure, Electrical and Electronic Engineering, Mechanical Engineering, Building and Construction, Civil and Structural Engineering, Solar reflectance, Ageing, Soiling, Cool roof, Building energy need, UV-Vis-NIR, Natural exposure, Building envelope, Riflettanza solare, Invecchiamento, Sporcamento, Cool roof, Fabbisogno energetico delledificio, UV-Vis-NIR, Esposizione naturale, Involucro Edilizio

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