Study on heat fluxes of green roofs based on an improved heat and mass transfer model

Analyzing heat fluxes of plants and soil is necessary to explore the thermal performance of green roofs. This paper presents mathematical expressions of heat fluxes of green roofs, and specially a heat and mass transfer model is built to get the distribution of temperature and moisture content in soil. The developed model is validated with experimental data from the intensive planted roof located in Chongqing. And the effectiveness of the model for predicting the temperature and water content variations are demonstrated by the comparison between the experimental results and simulation. Furthermore, the performance of green roof during summer in Chongqing is discussed based on the experiment. Through analyzing heat fluxes of green roofs, the study presents the contribution of each thermal behavior including reflection, convection, evapotranspiration and thermal storage to the thermal effects of the green roof quantitatively. The weight of various thermal behaviors of the green roof changes in different time, resulting in different thermal performance of green roofs. The study of the transient heat fluxes of green roofs will not only contribute to a high efficient usage but also a better application of engineering. (C) 2017 Elsevier B.V. All rights reserved.