Product modular architecture plays an important role in determining the environmental performance in the early design phase. Although methods have been developed to support modular product design for the environment, there are no integrated methods to address functionality and environmental performance jointly. We propose a method to support the selection of a modular architecture for products that considers both functionality and environmental performance in the early design phase. We incorporate the perspective of dozens of environmental strategies in developing implicative interaction types and scoring guidelines for modularization. The function-behavior-structure-life scenario (FBSL) representation is proposed to standardize the required information in this study. The relationship between product components is enumerated in a numerical design structure matrix (NDSM). A matrix synthesis method that considers all interaction types individually and then integrates them to obtain a good clustering addressing the objectives simultaneously is developed. We demonstrate the feasibility of the proposed approach on a vehicle air purifying system (VAPS) in case study.