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Article: Modeling the heat diffusion process in the abiotic layers of green roofs

TitleModeling the heat diffusion process in the abiotic layers of green roofs
Authors
KeywordsAbiotic layers
Evaporative cooling
Green roof
Heat diffusion
Theoretical model
Thermal performance
Wet porous medium
Issue Date2011
PublisherElsevier SA. The Journal's web site is located at http://www.elsevier.com/locate/enbuild
Citation
Energy And Buildings, 2011, v. 43 n. 6, p. 1341-1350 How to Cite?
AbstractGreen roofs have been increasingly installed to alleviate some common environmental problems. The thermal benefit of living vegetation on rooftop has been extensively studied. The individual and joint contribution of the non-living green roof layers, namely soil, rockwool (water storage) and plastic drainage layers, to thermal performance of green roof has seldom been assessed. This study evaluates the insulating and cooling effects of these abiotic materials. A one-dimensional theoretical model was developed to assess the heat diffusion process in the layers. The model was validated with empirical results from three experimental plots. A calibration procedure was successfully applied to determine key model parameters. The model can capture the most critical features of temperature variations and thermal performance of common abiotic green roof materials. The appreciable water-retention capacity of rockwool plays the dual role of supplying water to the soil to enhance evaporative cooling, and increasing the specific heat capacity of the green roof. The plastic drainage sheet with ample air spaces serves as an excellent thermal insulator. The model remains robust despite seasonal and weather variabilities. Our research findings contradict with some researches in the temperate region that the thermal dissipation in green roofs with dense vegetation is lower than thermally insulated bare roofs. The theoretical model could be used to simulate the micro-environmental conditions and predict the thermal performance of different materials to improve green roof design. © 2011 Elsevier B.V.
Persistent Identifierhttp://hdl.handle.net/10722/139845
ISSN
2015 Impact Factor: 2.973
2015 SCImago Journal Rankings: 2.073
ISI Accession Number ID
Funding AgencyGrant Number
Hui Oi Chow Trust
Midland Charitable Foundation
Stanley Ho Alumni Challenge Fund
Funding Information:

We would like to thank the anonymous reviewers for valuable suggestions to improve the manuscript, and acknowledge with gratitude the research grants kindly provided by the Hui Oi Chow Trust Fund, Midland Charitable Foundation, and Stanley Ho Alumni Challenge Fund. We gratefully appreciate Cheung Shing Yuk Tong Company for donating the green roof of our experimental site.

References

 

DC FieldValueLanguage
dc.contributor.authorJim, CYen_HK
dc.contributor.authorTsang, SWen_HK
dc.date.accessioned2011-09-23T05:58:01Z-
dc.date.available2011-09-23T05:58:01Z-
dc.date.issued2011en_HK
dc.identifier.citationEnergy And Buildings, 2011, v. 43 n. 6, p. 1341-1350en_HK
dc.identifier.issn0378-7788en_HK
dc.identifier.urihttp://hdl.handle.net/10722/139845-
dc.description.abstractGreen roofs have been increasingly installed to alleviate some common environmental problems. The thermal benefit of living vegetation on rooftop has been extensively studied. The individual and joint contribution of the non-living green roof layers, namely soil, rockwool (water storage) and plastic drainage layers, to thermal performance of green roof has seldom been assessed. This study evaluates the insulating and cooling effects of these abiotic materials. A one-dimensional theoretical model was developed to assess the heat diffusion process in the layers. The model was validated with empirical results from three experimental plots. A calibration procedure was successfully applied to determine key model parameters. The model can capture the most critical features of temperature variations and thermal performance of common abiotic green roof materials. The appreciable water-retention capacity of rockwool plays the dual role of supplying water to the soil to enhance evaporative cooling, and increasing the specific heat capacity of the green roof. The plastic drainage sheet with ample air spaces serves as an excellent thermal insulator. The model remains robust despite seasonal and weather variabilities. Our research findings contradict with some researches in the temperate region that the thermal dissipation in green roofs with dense vegetation is lower than thermally insulated bare roofs. The theoretical model could be used to simulate the micro-environmental conditions and predict the thermal performance of different materials to improve green roof design. © 2011 Elsevier B.V.en_HK
dc.languageengen_US
dc.publisherElsevier SA. The Journal's web site is located at http://www.elsevier.com/locate/enbuilden_HK
dc.relation.ispartofEnergy and Buildingsen_HK
dc.subjectAbiotic layersen_HK
dc.subjectEvaporative coolingen_HK
dc.subjectGreen roofen_HK
dc.subjectHeat diffusionen_HK
dc.subjectTheoretical modelen_HK
dc.subjectThermal performanceen_HK
dc.subjectWet porous mediumen_HK
dc.titleModeling the heat diffusion process in the abiotic layers of green roofsen_HK
dc.typeArticleen_HK
dc.identifier.emailJim, CY: hragjcy@hku.hken_HK
dc.identifier.emailTsang, SW: victsang@hku.hken_HK
dc.identifier.authorityJim, CY=rp00549en_HK
dc.identifier.authorityTsang, SW=rp00875en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.enbuild.2011.01.012en_HK
dc.identifier.scopuseid_2-s2.0-79953760328en_HK
dc.identifier.hkuros195111en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79953760328&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume43en_HK
dc.identifier.issue6en_HK
dc.identifier.spage1341en_HK
dc.identifier.epage1350en_HK
dc.identifier.eissn1872-6178-
dc.identifier.isiWOS:000290978900022-
dc.publisher.placeSwitzerlanden_HK
dc.identifier.scopusauthoridJim, CY=7006143750en_HK
dc.identifier.scopusauthoridTsang, SW=36926417600en_HK
dc.identifier.citeulike8759590-

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