Sustainable Manufacturing: A Primer

By Katie McKinstry, Graduate Student Researcher, University of California at Berkeley

If the greenhouse gases from a factory are not quantified, were they actually emitted?  If workers are exposed to hazardous substances and it is not reported, did it actually occur?

Graduate students in the field of Sustainable Manufacturing at the University of California at Berkeley are working to apply the basic mantras of manufacturing, "If you can't measure it, you haven't made it" to study sustainability throughout the production of engineered goods.  This brief introduction to sustainable manufacturing describes the state of the field and the value of applying a systematic approach to sustainability in engineering.

Sustainability, as defined by the Brundtland Commission "meets the needs of the present without compromising the ability of future generations to meet their own needs.” [1]. Sustainability is defined along three pillars: environmental, social, and economic metrics; collectively referred to as the "triple bottom line."  Sustainable Manufacturing is the study of the environmental, social, and economic impacts of producing engineered goods and services, and the modification of existing and the creation of new practices to reduce the impacts of engineered systems.

Sustainable manufacturing is the natural next step in the evolution of manufacturing philosophies. We can trace the trend toward efficiency and waste reduction to the concept of lean manufacturing that defined any expense that did not add value to the customer as waste. Six-sigma complimented lean manufacturing, and sought to improve quality by identifying and reducing errors in manufacturing processes.  These principles focused on efficiency of production, but not as much on materials, and even less on energy or even gave thought to human capital.  They measured progress using only a "single bottom line," money, to quantify their results. 

Sustainable manufacturing, instead, quantifies production using the triple bottom line: economic, environmental, and social impact.  This three-pronged approach prompts new insights into opportunities for system improvements. For example, Henry Ford said that waste was something you paid for and didn't use. What if we use energy to power an inefficient pump? Is that energy wasted? In traditional economic metrics, no! But looking at this problem through the lens of sustainable manufacturing frameworks, we can identify wasted energy and the negative environmental impacts associated with using excess energy.

Currently, engineers spend much of their time developing and debating appropriate metrics for sustainable manufacturing.  A sustainability metric is simply a way to quantify an impact along an indicator with respect to a certain quantity, or functional unit.  Some of the most common environmental indicators include greenhouse gas emissions, energy use, or emissions to air and water, though dozens of others exist. The economic indicator is money. Engineers normalize these impacts by a relevant quantity, or functional unit, for the purpose of comparing impacts.

No universal sustainability metrics exist, so most of the definition is either left to academics or industries to compare and quantify impacts within their respective enterprises.  To establish a useful indicator, engineers must ask two questions.  First, 1) what am I trying to measure, and 2) with respect to what? For example, an automobile manufacturing company might want to measure the impacts of their manufacturing.  Where would they start? First, they would need to decide what they were trying to measure.  Is it the impacts of just their factories, or perhaps their supply chain, or maybe every level, from supply chain to production in factories to distribution?  Next, they would need to decide with respect to what? Are they measuring per factory? Per car produced? Per dollar earned? These seemingly simple questions of accounting can have major impacts in the results of analyses.  The company would then need to consider what indicators they wanted to use to measure impact, and these could include energy, greenhouse gas emissions, water use, toxic emissions, etc.

Checkout the Laboratory for Manufacturing and Sustainability (LMAS) at UC Berkeley on YouTube

[1] U.N. General Assembly. Development and International Co-operation: Environment. Report of the World Commission on Environment and Development, Our Common Future, Annex to document A/42/427, 1987 (Oslo)