The presentation will demonstrate how POEs can help the commissioning process, with an emphasis on the benefits for a green building. There are three arguments that will be discussed in this presentation. That is: 1) POE provides a performance evaluation method that can verify whether the built environment is within acceptable range for the occupants. 2) POE's approaches are comprehensive and intuitive so that non-professionals can understand, which will encourage many people to discuss about the building by sharing POE results. 3) Data obtained during a POE study would make the following commissioning work easier. The discussion will be based on a literature study and experiences from a post-occupancy evaluation study at one green building. Because the POE was our primary source for the building study, the ideas and arguments exclusively stand on POE side point of view. Proposed idea would improve quality assurance of the building for the owners to receive what they wanted.