The Influence of Objective Setting on Optimal Design Pattern in Building Performance Optimization—Taking Rural Houses in Northwest China as an Example

Building performance optimization is a process aimed at obtaining optimal design parameter combination. The establishment of optimization objectives serves as the foundation for constructing the optimization logic, guiding the direction of building performance improvement. To clarify the impact of objective setting on optimal design schemes, firstly, a design framework centered on SVM and NSGA-II was developed. Then, taking rural houses in Xi’an of Northwest China as an example, based on single-objective, bi-objective, triple-objective and quadruple-objective combinations composed of four objectives including energy consumption, life cycle carbon emission, useful daylight illuminance, and life cycle cost, the proposed design methodology was used to generate Pareto solution sets and optimal design patterns for various scenarios. This study explores the influence of objective setting on the limits of objective range in Pareto-optimal solution, the sensitivity of design variables to objectives, the impact of objective setting on optimal design pattern, as well as the optimization potential and parameter value analysis of optimal design patterns. The results show that when the objective combinations differ, both intervals of Pareto-optimal solutions and parameter values of optimal design patterns exhibit variations. In view of building energy saving and rural economic conditions, the bi-objective optimization for BEC and LCC achieves an energy-saving rate of 78.9%, an LCCE reduction of 1040.60 kgCO₂/m², a UDI improvement of 5.8%, and an LCC reduction of 68.84 ¥/m², making it more suitable for rural house.