Design for energy efficiency in early stages: A top-down method for new product development

Abstract Design for energy efficiency (DfEE) is highly valued in improving the energy efficiency during product use and the decisions with a significant impact on the product’s energy-efficiency performance are made during early design stages. The product’s design features determined in early design stages are hierarchical in nature and the design process for new products is generally top-down. However, current DfEE methods tend to firstly improve the design features on the bottom level and then the higher level till the energy-efficiency target is achieved. The contradiction between the top-down design process and the bottom-up energy-efficiency improvement severely limits the innovation in new product design and hinders the emergence of highly energy-efficient products. In addition, the energy-efficiency improvement is divergent and can generate a large number of solutions, but the design process needs to be convergent and arrives at a few or a single best solution. This paper proposes a top-down DfEE method called three-step cyclic design method for new product development in early design stages. It is based on a spiral design process and a three-layer framework of DfEE activities. The former supports a top-down approach for energy-efficiency improvement, and the latter ensures a convergent DfEE process. The implementation of this method is detailed through a case study of a wind turbine.