Hydrometeorological determinants of green roof performance via a vertically-resolved model for heat and water transport

Ting Sun, Elie R. Bou-Zeid, Zhi Hua Wang, Eileen Zerba, Guang Heng Ni

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


In this study, the Princeton ROof Model (PROM) is developed, validated and used to simulate the hygrothermal dynamics of green roof systems. PROM is embedded within the framework of the Princeton Urban Canopy Model, with a multi-layer spatially-analytical heat transfer scheme and an improved hydrological module. The model is validated by comparing simulated surface temperature and soil moisture to the measurements at two experimental sites, one in Beijing, China and the other in New Jersey, USA. The results demonstrate that PROM is able to capture the diurnal cycle of roof temperatures and the soil moisture dynamics of green roofs with high accuracy. Driven by a 30-day summertime meteorological forcing from July 2001, PROM is used to investigate the green roof thermal improvement to the urban indoor and outdoor environments, compared to conventional roofs. The impact of green roofs is significant in reducing surface temperatures, and outdoor and indoor heat fluxes during this summer period. To quantify this thermal improvement, three indices related to surface temperature, outdoor heat flux and indoor heat flux, are introduced; and the dependence of these indices on hydrological and meteorological conditions is investigated. The results indicate that incoming solar radiation and medium layer moisture are the main determinants of the green roof performance.

Original languageEnglish (US)
Pages (from-to)211-224
Number of pages14
JournalBuilding and Environment
StatePublished - Feb 2013

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Civil and Structural Engineering
  • Geography, Planning and Development
  • Building and Construction


  • Green roof
  • Heat transfer
  • Thermal performance index
  • Urban Canopy Model
  • Urban hydrology
  • Urban microclimate


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