DOI: 10.5176/2301-394X_ACE13.133
Authors: Pasinee Sunakorn
Abstract:
Green roofs have become planning policy and building regulations in many high density cities for more than a decade in Europe and America. In Asia, Tokyo developed 10 Years Plan for Green Tokyo since 2006 with a policy of enhancing green roofs and Singapore largely adopt the idea of greening its buildings for the Garden City. Green roofs were proofed to reduce heat gain through roof significantly as well as mitigate Urban Heat Island especially in hot climate. In the tropic where plants are evergreen and climate is mostly summer, green roofs should be one of the best solution for building energy efficiency. In Thailand Green Building evaluation started last year in 2011 and gave credits to green roofs and walls, thus it became widely sought after . There were only a few available products to serve demand in Thailand. Investigation was done using local materials and process inventing modular green roof mat. Thermal performance was experimented in order to predict heat gain reduction of the system.
This paper reports thermal performance of green roof mat, which is local material of Thailand made from a combination of agro-industrial waste: coconut fiber, coffee waste and natural rubber liquid through hot press process. The green roof mat is a light weight modular extensive roof garden system with capability to grow sedums, bushes and groundcovers within the thickness of 5 cm and 30 x 30 cm width.
Comparison of heat gain reduction was made between full covered green roof mat and 5cm thick glass fiber insulation by measuring air temperature inside each experimental box compared with exposed concrete roof as reference roof. Green roof mat with plants full covered can reduce in box air temperature to average maximum of 10.47 °C lower than in box air of reference roof, while in box air of insulation roof was average 3.55 °C lower than that of reference roof in the daytime. At night, in box air temperature of full covered green roof mat was average 5.05 °C lower than that of reference roof while in box air of insulation roof was average 1.52 °C lower at night time. Shading effect, photosynthesis and evapo-transpiration of plants occurred in the daytime , and insulation property of green roof mat , thus result in reduction of heat gain through roof slab effectively.
Keywords: component; green roof, extensive roof garden, green roof mat, heat gain reduction; thermal performance
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