Phase change materials can be integrated in building walls to reduce heating energy consumption. However, proper design of the composite material requires a lot of complex calculations. In this paper, we present a methodology based on metamodeling in order to properly design phase change material composite solutions. A low-energy house example is chosen to develop our methodology, simulations being carried with TRNSYS. Box-Behnken design of experiments is used for data sampling in order to be able to produce a polynomial metamodel. First, the metamodel allows to have a profound understanding of the parameters influence: melting temperature, thickness, latent heat, density and thermal conductivity. Second, it is possible to extract from the polynomial form the optimal material properties. Third, the metamodel can be used to design or test different material solutions. Based on this methodology, it is possible to build a simple tool that can be used by architects and engineers. (C) 2015 Elsevier B.V. All rights reserved.