Abstract
This research evaluates evapotranspiration from rooftop vegetation and its effects of urban heat island mitigation and CO2 reduction in office building areas. First we conducted urban microclimate and air conditioning load simulation by using a coupled urban-canopy and building energy model (CM-BEM).Next, we calculated evapotranspiration on rooftops from latent heat flux derived from surface heat balance simulated by CM-BEM. From calculated evapotranspiration result, we determined required water volume and CO2 emissions for sprinkling water. Then, we quantified the CO2 reduction effects of rooftop greening by comparing the CO2 emissions for sprinkling water and the CO2 reduction by cooling energy savings calculated from air-conditioning load simulation. Finally, we evaluated the relationships between evapotranspiration and urban heat island mitigation effects and CO2 reduction effects.
