Designing envelope configurations of office building with the low construction cost and energy consumption is a discrete optimization problem. The configuration is currently determined merely on architects' experiences resulting in an inefficient expense or by building energy performance simulation which is time-intensive and involves complex processes. Based on an efficient regression equation to substitute complex energy simulators, this study developed an Office Building envelope Energy performance and configuration Model (OBEM) to provide envelope configurations, including construction material, sunshade type, sunshade length, window number, and window length and width for architects' reference. Also, Tabu search, which is effective in solving discrete optimization problems, was integrated with OBEM into an Optimal OBEM decision support system (OPOBEM). The OPOBEM was applied to a real office building construction for optimizing its envelope configuration at minimum construction budget under the energy conservation regulations of green buildings. The result shows that the optimized installation of sunshade type efficiently reduces solar heat gain according to the high variation of the sunshade coefficient, thus achieves the goal of energy conservation and reduces the envelope costs. Compared with architects' manual estimation, the optimized envelope design realizes nearly 41% budget savings, thus demonstrating the feasibility of the proposed OPOBEM. (C) 2016 Elsevier Ltd. All rights reserved.