In recent years, numerous papers, books, and conferences have centered on the subject of lessening the negative human impacts on the planet and on its ability to sustain life.
Often, from these discussions, specific goals have emerged, such as minimizing waste, increasing recycling, or approaching sustainability. Goal statements can be very useful in providing a vision of what needs to be achieved, and many of these discussions contribute to important parts of that vision. Yet, goals are only effective when they become reality. Approaches are being developed to achieve these goals across disciplines, industries, and sectors. It is clear, however, that these approaches are currently neither systematic nor comprehensive.
Green design and engineering focuses on how to achieve sustainability through science and technology. The Principles of Green Engineering provide a framework for planners, designers and engineers to engage in when designing new materials, products, processes, and systems that are benign to human health and the environment. A design based on these principles moves beyond baseline engineering quality and safety specifications to consider environmental, economic, and social factors.
The breadth of the principles’ applicability is important. When dealing with design architecture — whether it is the molecular architecture required to construct chemical compounds, product architecture to create an automobile, or urban architecture to build a city — the same green engineering principles must be applicable, effective, and appropriate. Otherwise, these would not be principles but simply a list of useful techniques that have been successfully demonstrated under specific conditions. In this article, we illustrate how these principles can be applied across a range of scales.
It is also useful to view the principles as parameters in a complex and integrated system. Just as every parameter in a system cannot be optimized at any one time, especially when they are interdependent, the same is true of these principles. There are cases of synergy in which the successful application of one principle advances one or more of the others. In other cases, a balancing of principles will be required to optimize the overall system solution. There are, however, two fundamental concepts that designers should strive to integrate at every opportunity: life cycle considerations and the first principle of green engineering, inherency.
Renewable Rather Than Depleting
Material and energy inputs should be renewable rather than depleting.
Inherent Rather Than Circumstantial
Designers need to strive to ensure that all materials and energy inputs and outputs are as inherently nonhazardous as possible.
Prevention Instead of Treatment
It is better to prevent waste than to treat or clean up waste after it is formed.
Design for Separation
Separation and purification operations should be designed to minimize energy consumption and materials use.
Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.
Output-Pulled Versus Input-Pushed
Products, processes, and systems should be “output pulled” rather than “input pushed” through the use of energy and materials.
Embedded entropy and complexity must be viewed as an investment when making design choices on recycle, reuse, or beneficial disposition.
Durability Rather Than Immortality
Targeted durability, not immortality, should be a design goal.
Meet Need, Minimize Excess
Design for unnecessary capacity or capability (e.g., “one size fits all”) solutions should be considered a design flaw.
Minimize Material Diversity
Material diversity in multicomponent products should be minimized to promote disassembly and value retention.
Integrate Material and Energy Flows
Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.
Design for Commercial “Afterlife”
Products, processes, and systems should be designed for performance in a commercial/valuable “afterlife.”