Evaluation of thermal performance of green roofs via field measurements and hygrothermal simulations

Yige Yang, Cliff I. Davidson, Jianshun Zhang

Research output: Contribution to journalArticlepeer-review

Abstract

Several studies have analyzed the heat flow impact of green roofs in hot weather, but few studies have examined the thermal performance during cold climate conditions. This study presents an experimental and numerical investigation of a large extensive green roof on the Onondaga County Convention Center in Syracuse, NY in both summer and winter conditions. Measured temperatures across the multilayers of the roofing system reveal the spatial and temporal variation of thermal conditions in the roofing system and the impact of the green roof. The CHAMPS-BES model (coupled heat, air, moisture and pollutant simulations for building envelope systems) has been applied to simulate the temperature profile through the layers of the green roof in which a new approach is developed to account for the evapotranspiration in the vegetation. In late fall without snow, the temperatures of the growth medium and roof membrane follow the diurnal cycle of ambient air temperatures but with smaller amplitude. Under extremely cold weather in winter with snow on the roof, the snow acts as an insulator, and heat flux is dominated by the temperature gradient between interior space and the snow layer. During the summer, the green roof significantly reduces the daily peak temperature of the membrane. In addition, the green roof moderates the heat flow through the roofing system and reduces the amount of air conditioning needed. This work also shows that the CHAMPS-BES model can be used to inform green roof design decisions.

Original languageEnglish (US)
Article number110800
JournalEnergy and Buildings
Volume237
DOIs
StatePublished - Apr 15 2021

Keywords

  • Energy simulation
  • Field measurement
  • Green roof
  • Heat flow
  • Thermal performance

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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