Coordinated optimal design of zero/low energy buildings and their energy systems based on multi-stage design optimization

As promising means to reduce carbon emission and energy consumption, zero/low energy buildings have been attracting increasing attentions. Multi-stage design optimization methods have been developed for zero/low energy buildings and their energy systems especially when a large number of design variables need to be optimized. However, these methods ignore the interactions between building envelope and energy system design optimizations, which can be addressed by simultaneous optimization methods requiring huge computation cost. In this study, a coordinated optimal design method is proposed as a computation cost-effective method for stand-alone and grid-connected zero/low energy buildings and their energy systems on the basis of multi-stage design optimization methods, to effectively consider the interactions between building envelope and energy system design optimizations. An iterative approach is adopted to coordinate multi-stage optimizations of building envelope and energy systems. The Hong Kong zero carbon building is used as the reference building to test and validate the proposed method. The results and experiences of the case studies show that the proposed coordinated design method can provide global optimal designs efficiently and robustly. The life cycle “cost” of the optimal designs is 4% less and unmet cooling load is over 22% less compared with existing multi-stage design methods.