New challenges for optimal design of nearly/net zero energy buildings under post-occupancy performance-based design standards and a risk-benefit based solution

One of the challenges in construction of nearly and net ZEBs is how to truly achieve the nearly and net energy goals after building occupancy. Traditional building design standards and practices are mostly based on design performance evaluation, but practices show that many designed nearly/net ZEBs failed to achieve the energy goals after building occupancy. To facilitate the practical achievement of nearly and net ZEBs, recently most of the newly-released ZEB design standards have turned to post-occupancy performance evaluation, posing great challenges to nearly and net ZEB design. However, the detailed challenges have not be comprehensively investigated, and effective optimal design methods which can facilitate the achievement of nearly and net ZEBs under these standards are still absent. In this study, new challenges of nearly and net ZEB design under the post-occupancy performance-based design standards are fully investigated, and a risk-benefit based optimal design method is proposed to facilitate the achievement of nearly and net ZEBs under these standards. The newly-released ZEB standard in China is taken as an example to investigate the challenges and test the proposed method. Results show that nearly and net ZEBs designed using conventional design method have high risk in achieving energy goals under these standards due to high risk in satisfying the requirement regarding non-renewable primary energy consumption after building occupancy. The proposed design method is effective to facilitate achieving energy goals under these standards based on the risk that decision-makers would like to take.