Minimal material use: Can you change the wall thickness of a part from half an inch to three-eighths of an inch without compromising its functionality? (eg. housing for a wide-screen TV)

Improved material choices: Is there a plastic that wasn't available ten years ago, that would make this part easier to produce, recycle, or transport, for the same cost? (eg. specify recyclable high-density polyethylene (HDPE) instead of acrylonitrile butadiene styrene (ABS))

Product reuse or recycling at end of life: Can the product be designed in a modular fashion, so that one part can be replaced to upgrade its function (eg. rethink throwaway cell phones by selling a consumer-replaceable slide-in memory/function board)

Minimal energy consumption: Is there a different method or machine for building or operating the system that uses less energy to run? (eg. redesign oxygen-flow mask so it uses lower-pressure, less expensive pump-system at the consumer end)

Manufacture without producing hazardous waste: (eg. the successful elimination of lead-based solder)