Coordinated robust optimal design of building envelope and energy systems for zero/low energy buildings considering uncertainties

Uncertainties exist throughout the life cycle of zero/low energy buildings, which may lead to low energy efficiency and even failure of achieving zero/low energy goal in operation. However, current design practice of the entire zero/low energy buildings, including building envelope and energy systems, seldom considers the uncertainties or roughly considers the uncertainties using safety factors in system sizing. Actually, the computing cost of optimal design of the entire zero/low energy buildings is high as numerous design options and parameters are involved. The consideration of uncertainties in the design would further increase the computing cost significantly, since each design option needs to be evaluated under a large number of uncertain scenarios. Thus, an efficient method is needed. In this study, a coordinated robust optimal design method is proposed to efficiently identify the global optimal design solutions for the entire zero/low energy buildings under uncertainties. The design process is divided into two stages, including robust design optimizations of building envelope and energy systems considering uncertainties. These two stages are coordinated to assure that the optimal design solution obtained is global optimal. Point estimate method is adopted for uncertainty quantification. A case study is performed to test and validate the proposed method using the zero carbon building in Hong Kong as the reference building. Results show that the proposed method is robust and efficient to identify the global optimal design solutions for the entire building under uncertainties. It can provide designs of better performance with reduced cost compared with current design methods.