Can Lean Practices Save the Planet?

Posted May 23, 2022 | Sustainability | Leadership | Amplify


Kevin Brennan outlines how Lean and Six Sigma process management systems could be changed to redefine waste in ways that capture environmental impacts. These models historically seek to eliminate waste in production processes by defining it as anything that does not contribute to increasing customer value. Brennan argues that this customer-centric definition of waste should be broadened to recognize that a focus on customer value leads to practices that reduce environmental quality.


Business cases for process improvement efforts focus on economic benefits for change, assessing whether work should be performed on the basis of improved revenue or reduced costs. However, as the costs of global heat­ing add up, we are learning that this mindset is short-sighted. Enterprises need to stop seeing sustainability as a cost imposed on them rather than an objective for process improvement.

Unfortunately, our existing process improvement methods aren’t designed for this. In this article, we discuss how to redefine waste from an environmental perspective. Even Lean approaches, which focus on “waste,” define waste solely on the basis of a customer’s willingness to pay for a product. Although conventional Lean and Six Sigma approaches can add value here, as the removal of unnecessary steps in processes and unwanted variation will almost certainly result in reduced use of resources, that is at best a happy side effect and not the goal.

If we want sustainability to be deeply integrated into the concept of waste, we will need to extend the concept to incorporate unsustainable waste, including overuse of resources, consumption of scarce materials, and externalities. We must also understand how to reconcile situations where customer value and environmental value require difficult tradeoffs and establish metrics that can be used effectively to assess environmental waste. The objective of these methods should be to ensure that process practitioners incor­porate sustain­able thinking into their improvement initiatives and that the true cost of unsustainable practices becomes visible.

The Limitations of Current Methods

It’s well known that Lean, as a process improvement and management system, originated in Toyota in the years following World War II. As Lean changed over time to accommodate knowledge work and software development, the focus has been on eliminating muda, or waste. This is generally defined as any activity the customer would not pay for (i.e., any activity that does not add customer value to the final product or service). Lean classically recognizes seven forms of waste, although some practitioners have expanded this list. Lean perceives that some muda activities must be performed but should be minimized to the greatest possible extent. Lean acknowledges two other forms of waste. One of those forms, muri (overburdening), seems like a natural fit for sustainability concerns, as unsustainable processes overburden our natural environment — but Lean has almost no tools to assess and eliminate it.

What about other common improvement methods? Six Sigma, developed by Motorola, focuses on delivering a consistent, high-quality product or service through eliminating variation (outcomes that diverge signif­icantly from the expected standard). Six Sigma involves identifying cases that fall outside an acceptable range, analyzing them to determine the causes of variation, and then implementing countermeasures. From the Six Sigma perspective, variations that fall below the acceptable standard of decision should be eliminated or mitigated, while performance above that standard may provide clues as to how to establish a higher level of quality.

A third approach to process improvement, not quite as well known as the others, is Eli Goldratt’s Theory of Constraints (TOC).1 TOC focuses on maximizing the potential output of a system. It posits that there is one step in any process that limits the amount of work that can be done, analogous to the “weakest link.” This is called the “constraint” or “bottleneck.” Goldratt argued that any improvement on any step other than the con­straint will not result in increased throughput, as work must always pass through the bottleneck.

TOC focuses on identifying the constraint, improving work at the constraint, and redesigning the rest of the process to maximize the constraint’s capacity. The nature of the constraint may shift over time, and it is possible for it to be something outside your process, such as input availability or market demand.

Each of these approaches comes from a distinct perspective on what will improve a process, so they have often been combined. Other tools aimed at building more efficient, customer-focused processes have also entered the practitioner toolkit, including service design and process mining. All these methods can be used to make processes more efficient and reduce the overburden on the environment, but none are designed for it.

Reframing Value for Sustainability

At a high level, it appears simple to reorient these methods to focus on a more sustainable approach. In Lean, we could perhaps define waste from the perspective of sustainability. In Six Sigma, we could examine processes to monitor the use of unsustainable materials or chemicals, aiming to move the standard to a lower level. In TOC, we could look at the environment itself as a constraint. However, there are significant problems when we try to apply these simplistic redef­ini­tions in the context of real process improvement work.

Lean defines “value” around the needs and wants of the customer and “waste” as any activity that does not contribute to meeting them. It’s relatively easy to envision scenarios where making a process more sustainable runs up against this objective. For example, someone purchasing a house might view an environ­mental assessment as wasteful, since it adds to the cost without increasing their enjoyment. In fact, most environmental issues (as they concern the commons, rather than individual property) are at risk of falling prey to these types of concerns.

One might say this view is overly simplistic. After all, people are increasingly concerned about global heating and the related effects on climate and weather, and this increased awareness will affect customer perception of value, reducing the risk that environmentally sound decisions will be considered waste. However, this is not the same thing as designing a process to be sustainable! Even if sustainability is considered to provide customer value, there will be many cases where it isn’t viewed as adding enough customer value to justify significant investment in it.

In addition, applying Lean principles to a process often results in improvements to the sustainability of that process as a side effect. The removal or improvement of a process step will often reduce the required resources for that step, by necessity. This aspect of Lean is not coincidental; it reflects the original purpose of Lean methods at Toyota.

Since Toyota had to operate under supply constraints and had limited opportunity to seek outside invest­ment, it sought ways to increase the quantity and variety of its automotive products without compro­mising quality or requiring investment. Lean was developed as a solution to this quandary, as remov­ing unnecessary process steps freed up people and equipment to be used elsewhere.

If we look at the seven wastes, we find that a number of them have obvious connections to sustainability. Transportation from site to site generally involves fossil fuel–burning vehicles, and overproduction involves excess consumption of resources. Overprocessing likely involves the consumption of excess resources. Defects require increased consumption during rework, and inventory of raw materials could be tied back to overuse of resources.

Although this can make a process more sustainable, it doesn’t necessarily have that effect. The main point remains: customer value and sustainability aren’t the same thing, and as long as Lean practitioners are focused exclusively on the former, the latter remains a lower priority. And after all, muda is a useful concept. It has informed a vast number of process improvement efforts around the world and is well understood by practitioners. Attempting to redefine it, or add even more forms of waste to it, is fighting against decades of practice and training. It makes little sense to change the existing understanding of muda when we have alternatives.

Muda comes with well-understood tools to tackle it, and its elimination has obvious and immediate positive effects. The same is true of mura (the waste of varia­bility), which comes with tools like hejunka and takt time, as well as some borrowed from Six Sigma.

To date, muri has been seen as an injunction to management more than as a practice with tools of its own. However, it is a natural fit for encompassing sustainability issues. Muri is the direct overburdening of the people, equipment, or systems used by a given process. It’s not much of a stretch to expand it to encompass the overburdening of systems the process sits within — including the environment.


An unsustainable process is unsustainable precisely because it places more stress on the environment than it can ultimately bear, whether that’s from resource overconsumption or byproduct dumping. In contrast, a sustainable process can continue indefinitely; it is designed so the resources it uses are recycled or replenished.

If we want to incorporate sustainability into process improvement, we must develop a toolkit and integrate it with existing Lean processes and methods, such that they work together to produce the results we’re seeking.

Importantly, many practitioners believe muri is the true root cause of many other forms of waste. If we follow that line of logic, we should find a great deal of oppor­tunity for improvement by actively controlling it.

The Wastes of Muri

By examining various definitions of sustainability, we see that there are also seven wastes of muri: expediency, contamination, hazards, offloading, exhaustion, squandering, and overloading. This list may evolve over time, but it serves as a good start for people looking to make processes and products more sustainable.

Strictly speaking, the associated cost of a value stream should be considered when evaluating sustainability because overly high costs can lead to the failure of a product or enterprise. Although a category for “expense” could certainly be added, there is little risk the cost of a process will be overlooked! One thing to keep in mind, however: a process step may include more than one waste of muri. Practitioners may also find it useful to review other literature on sustainable value stream mapping.2

Let’s take a closer look at the seven wastes of muri and their relation to processes and sustainability:

  1. Expediency comes as a result of short-term thinking and can be the root cause of many other wastes. Pursuing expedient solutions results in short-term “fixes” that break down over time and/or mask the real costs of a decision. Expediency reduces or eliminates careful consideration of the long-term sustainability of a product or process. Expediency results in processes that include many workarounds or short-term fixes. Expedient processes should be carefully evaluated and redesigned so they can work acceptably in the long term.

  2. Contamination occurs when toxic substances are created or released into the environment. This includes pollution, construction use, and use of products with toxic chemicals without a process in place to recapture/safely reuse the substance or neutralize its effects. Processes that cause contamination should be redesigned, and past contamination should be cleaned up.

  3. Hazards are any element of a product or process that puts personal safety at risk, whether directly or indirectly. The hazard may apply to operators involved in the work, customers, or external stakeholders. The waste of hazard means the process cannot be performed as it is without the possibility of injury or death. Processes or equipment that create hazards should either be redesigned to ensure safety or have countermeasures put in place to minimize the risk.

  4. Offloading occurs when the costs or effort required to make a process sustainable are placed on another. This can occur because the process does not include steps to replace renewable resources (such as cutting down a forest without replanting) or when attempts are made to balance the costs of an unsustainable process by purchasing tax credits or offsets. Offloading also occurs when a problem is left for future generations to clean up and resolve. Processes that offload problems onto others should be redesigned so the problem does not occur, or a countermeasure should be put in place that forces the organization to clean up the resource.

  5. Exhaustion occurs when a nonrenewable resource is used as part of a process or product. Whether the resource is plentiful or scarce, there is a limited supply of it, and each execution of the process uses some of that finite supply. Ultimately, a process that exhausts a resource cannot be sustainable. Exhaustion can be addressed by redesigning the product such that the resource is not required or by taking steps to recover the used resources through recycling.

  6. Squandering is the use of a resource beyond the minimum needed to perform the process or to produce an equivalent good. This can include overuse of materials and energy. It is critical to consider squandering in the context of equivalent goods. Processes like cryptocurrency mining and trading are similar in use to other financial instruments, but they require immense and increasing use of computing resources and power. Processes that squander resources should be redesigned to substantially reduce resource usage or be replaced with processes or products that put lower demands on the environment.

  7. Overloading is the waste that occurs when some­thing is pushed beyond its capacity on a regular basis. This includes staff overwork, excessive use of a machine beyond its maintenance cycles or tolerances, and drawing renewable resources from an ecosystem to the point where it declines or collapses. Overloading introduces risk into the process because the overloaded resource may suddenly break or become unable to sustain the demands placed on it. If a resource is overloaded, the process must be redesigned with the understanding that the resource is a constraint (TOC may be helpful here) and the load on the resource managed to be below the level where it is at risk.


Recent scientific research has made it clear that the global ecosystem is at a crisis point and that we risk collapse without major changes to our economy and infrastructure. As process improvement practitioners, we find ourselves in a place where we can make a significant contribution to this effort by redesigning products, processes, and supply chains to reduce the stress they place on our environment.

Recognizing that these unsustainable practices are wasteful — and at least as important as the traditional waste Lean seeks to eliminate — is a necessary first step to developing the tools that will allow us to ensure a livable world for our children and grandchildren.


1Goldratt, Eliyahu M. The Goal: A Process of Ongoing Improvement. North River Press, 2012.

2Faulkner, William, and Fazleena Badurdeen. “Sustainable Value Stream Mapping (Sus-VSM): Methodology to Visualize and Assess Manufacturing Sustainability Performance.” Journal of Cleaner Production, Vol. 85, 15 December 2014.

About The Author
Kevin Brennan
Kevin Brennan is an independent consultant in product management and business architecture and Professor at George Brown College, Canada. He has led organizations through strategic and business unit planning and execution, played a leadership role in enterprise change, developed and launched multiple products for a global audience, and managed a product portfolio through the entire product lifecycle. Mr. Brennan is best known for leading the… Read More