This paper presents a computational framework for reducing environmental impact of product development in consideration of product design, manufacturing, and the supply chain concurrently. This framework incorporates a number of factors that ecologically influence the product lifecycle activities into product architecture design. They allow a systematic variation of manufacturing bill of materials. CAD-based functions are developed to ensure that the variation results satisfy product functional requirements and are interference-free during assembly. A cradle-to-gate lifecycle assessment is conducted on the bill of materials. Optimization schemes are integrated with the variation process to search for optimal results. This work realizes sustainable product development by offering a tool of ecological decision making in the system design stage.