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Article: Theoretical evaluation of thermal and energy performance of tropical green roofs

TitleTheoretical evaluation of thermal and energy performance of tropical green roofs
Authors
KeywordsEnergy balance model
Energy-efficient building
Green roof
Latent heat dissipation
Passive cooling
Thermal performance
Issue Date2011
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/energy
Citation
Energy, 2011, v. 36 n. 5, p. 3590-3598 How to Cite?
AbstractThe thermal and energy efficiency of tropical green roofs is assessed by a theoretical model to clarify the contribution of underlying factors. The suitability of 1400 high-rise public housing blocks in Hong Kong for rooftop greening was assessed by remote sensing images. Weather and microclimatic-soil monitoring data of an experimental green roof provided the basis for computations. Roof greening prevented a huge amount of solar energy at 43.9 TJ in one summer from penetrating the buildings to bring significant energy saving. Thermal performance of humid-tropical green roofs, with greater latent heat dissipation, is twice more effective than the temperate ones. The energy balance model shows that solar energy absorption by bare and green roofs depends on shortwave rather than longwave radiation. Heat flux into a building indicates a one-day time lag after a sunshine day. With restricted evapotranspiration, bare roofs have more sensible heat and heat storage than green roofs. The bare roof albedo of 0.15, comparing with 0.30 of green roof, renders 75% higher heat storage. Small increase in convection coefficient from 12 to 16 could amplify 24% and 45% of latent heat dissipation respectively for bare and green roofs. Doubling the soil water availability could halve the heat storage of green roofs. © 2011 Elsevier Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/139849
ISSN
2015 Impact Factor: 4.292
2015 SCImago Journal Rankings: 2.350
ISI Accession Number ID
Funding AgencyGrant Number
China Light and Power Company Limited
Stanley Ho Alumni Challenge Fund
Funding Information:

We would like to thank the comments from anonymous reviewers, and acknowledge with gratitude the research grants furnished generously by the China Light and Power Company Limited and Stanley Ho Alumni Challenge Fund, and the laborious field work assistance kindly provided by Jeannette Liu and W.Y. Wong.

References

 

DC FieldValueLanguage
dc.contributor.authorTsang, SWen_HK
dc.contributor.authorJim, CYen_HK
dc.date.accessioned2011-09-23T05:58:04Z-
dc.date.available2011-09-23T05:58:04Z-
dc.date.issued2011en_HK
dc.identifier.citationEnergy, 2011, v. 36 n. 5, p. 3590-3598en_HK
dc.identifier.issn0360-5442en_HK
dc.identifier.urihttp://hdl.handle.net/10722/139849-
dc.description.abstractThe thermal and energy efficiency of tropical green roofs is assessed by a theoretical model to clarify the contribution of underlying factors. The suitability of 1400 high-rise public housing blocks in Hong Kong for rooftop greening was assessed by remote sensing images. Weather and microclimatic-soil monitoring data of an experimental green roof provided the basis for computations. Roof greening prevented a huge amount of solar energy at 43.9 TJ in one summer from penetrating the buildings to bring significant energy saving. Thermal performance of humid-tropical green roofs, with greater latent heat dissipation, is twice more effective than the temperate ones. The energy balance model shows that solar energy absorption by bare and green roofs depends on shortwave rather than longwave radiation. Heat flux into a building indicates a one-day time lag after a sunshine day. With restricted evapotranspiration, bare roofs have more sensible heat and heat storage than green roofs. The bare roof albedo of 0.15, comparing with 0.30 of green roof, renders 75% higher heat storage. Small increase in convection coefficient from 12 to 16 could amplify 24% and 45% of latent heat dissipation respectively for bare and green roofs. Doubling the soil water availability could halve the heat storage of green roofs. © 2011 Elsevier Ltd.en_HK
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/energyen_HK
dc.relation.ispartofEnergyen_HK
dc.subjectEnergy balance modelen_HK
dc.subjectEnergy-efficient buildingen_HK
dc.subjectGreen roofen_HK
dc.subjectLatent heat dissipationen_HK
dc.subjectPassive coolingen_HK
dc.subjectThermal performanceen_HK
dc.titleTheoretical evaluation of thermal and energy performance of tropical green roofsen_HK
dc.typeArticleen_HK
dc.identifier.emailTsang, SW: victsang@hku.hken_HK
dc.identifier.emailJim, CY: hragjcy@hku.hken_HK
dc.identifier.authorityTsang, SW=rp00875en_HK
dc.identifier.authorityJim, CY=rp00549en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.energy.2011.03.072en_HK
dc.identifier.scopuseid_2-s2.0-79955643960en_HK
dc.identifier.hkuros195115en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79955643960&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume36en_HK
dc.identifier.issue5en_HK
dc.identifier.spage3590en_HK
dc.identifier.epage3598en_HK
dc.identifier.isiWOS:000291411400135-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridTsang, SW=36926417600en_HK
dc.identifier.scopusauthoridJim, CY=7006143750en_HK
dc.identifier.citeulike9232206-

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