The building envelope shape is the most salient design characteristic and has a significant influence on energy consumption during the post-occupancy service life and carbon emission. However, during the conceptual design phase, envelope shape finding is defined without considering the energy performance during post-occupancy service life and sustainable characteristics (i.e. low carbon emission). In addition, there is no suitable method for designers to make such calculations. To bridge the post-occupancy service life in efficiency, this research developed an ideal envelope shape finding approach to facilitate the conceptual design phase. The steady-state principle has been used to predict the thermal flow and energy impact on the aspect ratio of various shapes, and compactness. Integrated dynamic simulation and particle swarm optimization method were used to identify the optimal and sub-optimal combinations of envelope shapes for energy consumption and carbon emission. The findings of this research provide a benchmark of energy consumption characteristics of envelope shape and a cut-off range for low carbon emission envelope design. This is one of the simplified design approach facelift the conventional design process to predict post-occupancy energy performances and carbon emission impact
