For some existing buildings with out-of-date facilities, energy efficiency retrofit is a promising method to reduce energy consumption of buildings with small amount of investment. Among many choices of alternative efficient interventions, different strategies to select them are closely related with retrofit cost, energy saving and net present value (NPV), which are conflicted with each other. A multiobjective energy efficiency retrofit problem has been modeled to cover these essential objectives. The multiobjective neighborhood field optimization (MONFO) algorithm is utilized to solve the proposed model for finding optimal retrofit strategies. Besides retrofit strategies, maintenance strategies of repairing or replacing failed interventions are also evaluated and incorporated in the proposed model. Results in case studies indicate that MONFO is a suitable algorithm to obtain accurate and diverse Pareto optimal solutions for energy efficiency retrofit, and that optimization of maintenance strategy can improve the overall performance of project compared with empirical maintenance strategy. (C) 2014 Elsevier B.V. All rights reserved.