Green roofs as passive system for energy savings in buildings during the cooling period: use of rubber crumbs as drainage layer
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The building sector is responsible for most of today’s energy and materials consumption. Construction systems such as green roofs can improve the energy performance of buildings, but meanwhile, they themselves should be more sustainable. This research focuses on the study of the benefits, in terms of energy consumption, of an extensive green roof (without insulation layer) in comparison to a conventional flat roof solution (with insulation) under Mediterranean continental climate. Moreover, in order to improve the sustainability of this system, the use of recycled rubber instead of traditional stone materials as drainage material is evaluated as well. For this purpose, the electrical energy consumption of the cooling system and thermal behaviour of three identical experimental cubicles, with only differences on the roof composition, was evaluated during summer period. The results show that a simple extensive green roof 9 cm thickness provides a reduction of 5 % in case of rubber crumbs and 14 % in case of pozzolana, in terms of electrical energy consumption, than a conventional flat roof with an insulation layer of 3 cm polyurethane, even when only the 20 % of the surface is covered by plants. Furthermore, small differences in thermal behaviour were observed when replacing volcanic gravel by recycled rubber crumbs as drainage material.
KeywordsGreen building Building envelope Extensive green roof Energy consumption Passive system Recycled rubber crumbs
This work was partially funded by the Spanish government (ENE2011-28269-C03-02 and ULLE10-4E-1305) and the European Union (COST Action TU0802), in collaboration with the companies Gestión Medioambiental de Neumáticos S.L (Polígon Industrial Piverd s/n, Maials.) and Soprema. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534).
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