Building performance optimization (BPO) paired with building performance simulation (BPS) is a promising solution for evaluating many different design options and obtaining the optimal or near-optimal solution for a given objective or combination of objectives while complying with constraints. This chapter discusses major obstacles to BPO in the building design and construction industry including lack of appropriate tools, lack of resources, and the requirement that the problem be very well defined. The chapter explains the state-of-the-art and future research and development needs for Net Zero-Energy Buildings (ZEB) optimization tools in practice and its use for design and operation of buildings for energy, comfort, and cost optimization. ...