In this study, an experimental setup of a green roof system was established on the rooftop of a com-mercial building for computer model validation. Then a generic office building constructed with green roof was modeled using Energy Plus and its energy performance was evaluated under different future climatic conditions over three future periods (2011–2030, 2046–2065 and 2080–2099) and two emis-sion scenarios (SRA1B and SRB1). The findings show that a combination of thicker soil layer, lower plant height and higher value of leaf area index (LAI) can provide a better thermal insulation effect in a green roof system. The results reveal that a building case with soil thickness of 0.4 m, plant height of 0.05 mand LAI of 5 can maintain the year-round A/C energy consumption no more or less than the current level,ranging from −2.4% to −10%, under the future climatic conditions (2011–2030 and 2046–2065, for bothe mission scenarios). Economic evaluation on the application of green roof was also conducted. Taking into account the replacement cost of a conventional bare roof, the cost payback period is about 10 years.The application of green roof system can act as a potential measure to cope with the impact of climate change.