Energy performance assessment on vertical greening systems with green roof in hot summer and cold winter regions based on long-term experimental data

The integration of vertical greening systems and green roofs with buildings is currently a popular urban development approach aimed at mitigating the urban heat island effect and promoting sustainable development. However, most existing studies on vertical greening systems and green roofs are based on short-term experimental results, which might not reflect their overall performance. Thus, this paper aims at evaluating the energy performance of vertical greening systems and green roofs in a hot summer and cold winter region in China over a three-year period. Although energy-saving was found in summer, occasionally increases in energy demand occurred in winter. It confirms the need for long-term experiments to avoid contingency. The energy saving rate of vertical greening systems and green roofs was approximately 27.49 %-42.48 % (monthly) or 28.89 %-34.02 % (quarterly) during the cooling period (33.84 % on average), and approximately -7.42 %-13.79 % (monthly) or -1.19 %-6.58 % (quarterly) during the heating period (3.6 % on average). The impact of climatic conditions on energy saving rate was evaluated. It was found that solar radiation intensity is the most important factor, followed by the outdoor air temperature and relative humidity. This paper provides an insight on the long-term energy-saving benefits of vertical greening systems and green roofs in hot summer and cold winter regions and the correlation between climatic conditions and energy saving rate.