Eco-Design is about incorporating environmental aspects as early as possible into the design process. Much like the financial costs of product development, 80% of the environmental costs of packaging are determined in the first 20% of the design process. Considering environmental factors as early as possible can substantially improve the environmental performance of packaging throughout its life cycle (extraction, transport, distribution, packaging, use, end of life) without jeopardising the existing design process and the mainstay specifications relating to cost, quality, functionality and aesthetics.
For more information see the DfE page here.