Green-roof effects on neighborhood microclimate and human thermal sensation

Lilliana L.H. PENG, Chi Yung JIM

Research output: Contribution to journalArticle

82 Citations (Scopus)

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 oC, and IGR by 0.5-1.7 oC, 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. Copyright © 2013 by the authors.

Original languageEnglish
Pages (from-to)598-618
JournalEnergies
Volume6
Issue number2
DOIs
Publication statusPublished - 25 Jan 2013

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Roofs
Cooling
Thermal comfort
Heat
Heat Stress
Greening
Scenarios
Energy Conservation
Advection
Modeling Method
Open set
Lateral
Thermal effects
Coverage
Vertical
Monitoring
Air
Human
Hot Temperature
Energy conservation

Citation

Peng, L. L. H., & Jim, C. Y. (2013). Green-roof effects on neighborhood microclimate and human thermal sensation. Energies, 6(2), 598-618. doi: 10.3390/en6020598

Keywords

  • Green roof
  • Climate change
  • Cooling effect
  • Human thermal comfort
  • Urban heat island
  • Compact city
  • Sustainable urban design