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Energies 2013, 6(2), 598-618; doi:10.3390/en6020598
Article

Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation

 and *
Received: 30 November 2012; in revised form: 21 January 2013 / Accepted: 21 January 2013 / Published: 25 January 2013
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Abstract: Green roofs have been recognized as an effective sustainable design tool to mitigate urban heat island (UHI) effects. Previous studies have identified green-roof benefits in cooling and energy-conservation at the building scale, with limited exploration of the wider influence on neighborhood microclimate and human thermal comfort (HTC). This paper investigated the impacts of community-scale green-roof installation on air temperature and HTC in five typical residential neighborhoods of subtropical Hong Kong. The microclimate models ENVI-met and RayMan permitted studies of two main green-roof scenarios, namely extensive (EGR) and intensive (IGR). Microclimatic monitoring data from a local experimental green-roof site validated the modeling methods. The results verified that green-roof cooling effects were not restricted to rooftops, but extended to the ground to improve neighborhood microclimate. EGR reduced pedestrian-level air temperature by 0.4–0.7 °C, and IGR by 0.5–1.7 °C, with maximum effect in open-set low rise sites. Coverage by building footprints and building height dampened lateral and vertical advection of cool air generated by green roofs. Roof greening also improved notably the rooftop-podium level HTC. Diurnal duration of high heat stress was reduced by 6–9 h for EGR scenarios, and 9–11 h for IGR. The findings indicated that large-scale green-roof installation could bring neighborhood-wide cooling, mitigate urban heat island effect, and furnish more comfortable thermal environment for urban residents.
Keywords: green roof; climate change; cooling effect; human thermal comfort; urban heat island; compact city; sustainable urban design green roof; climate change; cooling effect; human thermal comfort; urban heat island; compact city; sustainable urban design
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Peng, L.L.; Jim, C.Y. Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation. Energies 2013, 6, 598-618.

AMA Style

Peng LL, Jim CY. Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation. Energies. 2013; 6(2):598-618.

Chicago/Turabian Style

Peng, Lilliana L.; Jim, C. Y. 2013. "Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation." Energies 6, no. 2: 598-618.


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