Green engineering principles are based on the green chemistry principles, developed to help guide chemical engineers. As for the Green Chemistry principles, the 12 Green Engineering principles provide a checklist for scientists and chemical engineers to use when designing new materials, products, processes and systems. Making products, processes and systems more inherently benign can come about by either changing the inherent nature of the system, or changing the circumstances/conditions of the system to reduce the release of toxins and associated exposure to harmful effects, or both. As for green chemistry, it is therefore important to apply these Green Engineering principles systematically, and together rather than in isolation, to achieve significant improvements. The 12 principles are summarized as follows: