Optic-energy performance of innovative and traditional materials for roof covering in commercial buildings in central Italy PISELLO Anna Laura 1, a 1 CIRIAF – University of Perugia. Via Duranti 67, 06125 Perugia, Italy a pisello@crbnet.it Keywords: Cool roof; energy efficiency in buildings; building envelope material; thermal-energy dynamic simulation; urban paving; urban heat island. Abstract. Innovative and traditional solutions for roof coating and urban paving are under development in order to study their effect both as passive cooling strategies for buildings and as effective tools for urban heat island mitigation. This paper deals with the optic-energy in-lab and numerical analysis of three materials used for roof covering and urban paving in Italy. Bitumen covering, cool painting and natural gravel covering are taken into account. Solar reflectance measurements shows that gravel optimize this property by more than 20% with respect to the bitumen covering of classic streets paving. The three materials are also evaluated in terms of roof covering in commercial buildings with flat roofs. Dynamic simulation results demonstrated that innovative cool membranes are able to optimize building year-round energy efficiency by 19.3%. Nevertheless, natural gravel covering produce important energy saving (15.6%) with respect to bitumen roof membrane configuration. Introduction The effect of the built environment on urban climate represents an acknowledged phenomenon producing important local climate conditions such as Urban Heat Islands [1-2]. In this view, the study of new, low impact and effective solution to reduce energy requirement for cooling in buildings represent a key research issue [3]. To this aim, the development of cool materials for building roofs has represented an essential purpose of several research contributions all over the world [4-5]. These works mainly focused on the implementation of innovative high performance materials for urban paving and roof coatings [6], which thermal-energy characteristics were evaluated through experimental monitoring and numerical methods with varying several boundary conditions. In particular, interesting studies concerned the application of cool coatings on buildings’ roof, in hot climatological conditions [7]. Synnefa et al. in [7] developed a calibrated and validated numerical model of a school building in Athens where they implemented cool roof solution, which performance were also studied through thermography analysis. The same studies were often characterized by in-lab preliminary assessment of the investigated materials, where solar reflectance and thermal emittance were measured by spectrophotometer and portable emissometer. These two parameters, in fact, maily determine the “cooling” potential of roof coating and urban paving. The overall performance is described by the Solar Reflection Index [8]. Recently, further studies focused on the possibility to earn good energy and environment results from the application of cool materials in buildings even in those climate regions where the cooling requirement is not prevalent with respect to heating requirement. Kolokotroni et al. in [9] studied the possibility to apply cool roofs in London area, though coupled experimental and numerical methods. Additionally, Mastrapostoli et al. in [8] evaluated the thermal-energy effect of innovative cool coatings for application in cold climate of Northern Europe. They examined new materials through in-lab measures of reflectance, emissivity and durability. Therefore, they evaluated the effect of application of these new materials in an industrial building located in Germany, where the internal gains prevailed outdoor cold climate boundary conditions. Given the huge potential of these materials, recent research efforts focused on the possibility to reduce their visual impact, in order to develop new materials and solutions with good cooling capability but non-impactive visual Advanced Materials Research Vols. 884-885 (2014) pp 685-688 Online available since 2014/Jan/16 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.884-885.685 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 141.250.54.18-20/01/14,16:22:22)