Sergio Kemmer: "Lean Is Not About Implementing Tools — It Is About Changing the Way People Think"

The fourth episode of The Process People features Sergio Kemmer, a civil engineer from Brazil who has been based in the UK since 2010 and works as a lean construction consultant and coach. His practice is focused on helping construction project teams deliver more predictably, more safely, and more efficiently — not by installing tools, but by changing the behaviours and habits that determine whether tools ever get used properly.

The conversation with Alain Cohen of Famla AI covers the defining insight of Sergio's career — that centralised top-down planning fails on complex construction projects and that collaborative planning is not a preference but a prerequisite for reliable delivery. It also covers the two conditions he believes most lean transformations fail to create: sustained leadership buy-in and psychological safety on the ground. And it closes with a grounded, pragmatic perspective on where AI fits into lean construction practice today and where he expects it to go.

Who Is Sergio Kemmer? Lean Construction Consultant and Coach

Sergio Kemmer is a civil engineer by background who has spent his career at the intersection of construction project management and lean practice. After working in Brazil, he moved to the UK in 2010 and has since built a consulting practice focused on lean construction coaching: working directly alongside project teams — on site and off — to help them understand what lean is, how it applies to the specific conditions of construction, and how to make the cultural shift that determines whether lean practice actually takes root.

Construction is a sector with its own distinct challenges for lean adoption. Unlike manufacturing, where processes repeat in controlled environments, construction projects are unique, involve large networks of subcontractors operating simultaneously, and unfold in physical environments that change daily. The principles of lean apply — minimising waste, maximising customer value, engaging the people doing the work in the planning process — but the tools and practices that carry those principles into construction look different from those used on a factory floor. Sergio's work lives in that translation.

The Conventional Wisdom Sergio Kemmer Abandoned: Centralised Planning

Asked about a piece of business wisdom he followed early in his career and later rejected, Sergio Kemmer was specific and vivid. Early in his career as a planner on a construction project, his manager told him to develop the production plan himself and then go to site to tell the workers what to do. The instruction was well-intentioned. The assumption behind it — that the planning expertise sat entirely with the planner and that workers were there to execute, not to contribute — was one that Sergio had already been challenged on by a professor who introduced him to lean construction during his final year at university.

He tried the top-down approach. Within a week it was clearly failing. The workers on site were disengaged, the plan did not reflect operational reality, and the gap between what the planner had designed and what was actually achievable was obvious. The conversation that followed with his manager was the turning point: Sergio made the case that on a complex project with multiple subcontractors and changing conditions, collaborative planning was not an ideal but a practical necessity. If you want a reliable plan, you have to build it with the people who are going to execute it.

What Lean Construction Actually Is: Philosophy First, Tools Second

Sergio Kemmer's most consistent argument throughout the conversation is one that practitioners in any improvement discipline will recognise: lean is not a toolkit. It is a philosophy, a set of principles about how work should be organised and how people should be treated, and the tools are only useful insofar as they carry those principles into practice.

In construction, lean traces its roots to the Toyota Production System through the work of Professor Larry Koskela, a Finnish researcher who went to Stanford as a visiting researcher in 1991 and wrote a report that is still one of the most cited works in the field — making the case that construction needed to look at what Toyota had built in manufacturing and adapt those principles to the specific conditions of building projects. That report triggered a movement that has been running for more than thirty years, including the formation of the International Group for Lean Construction and an annual conference drawing researchers and practitioners from around the world.

Sergio also recommends The Toyota Way by Jeffrey Liker, which describes the fourteen principles that made Toyota's production system work — principles that centre not on specific tools but on the culture of continuous improvement, respect for people, and long-term thinking that the tools were designed to express.

The practical implication of this philosophy-first view is significant for how lean transformation is approached. When organisations treat lean as a set of tools to implement, they typically see initial gains that are not sustained. When they treat it as a change in how people think and work together, the tools become expressions of new habits that compound over time. The difference between a lean initiative that stalls and one that becomes part of how a project team permanently operates comes down almost entirely to whether the cultural dimension was taken seriously from the start.

What Sergio Kemmer's Week Actually Looks Like: Go to the Gemba

Asked what a typical week looks like in practice, Sergio Kemmer gave an answer rooted in the same principle he applies to planning: go to where the work happens. In lean, this is called the Gemba — the Japanese term for the actual place where value is created. In construction, it is the site.

His weeks are split between on-site and off-site engagement. On site, he works directly with operatives, project managers, and supporting functions — supply chain, design, quality management — listening to the problems they are experiencing and building with them what the solutions might look like. The emphasis on building with rather than for is deliberate and consistent: the same principle that governs collaborative planning governs how he approaches improvement work more broadly.

A practical example he gives is the Last Planner System, a well-established method in lean construction that formalises collaborative planning: the plan is developed with the people who will execute it, commitments are made explicitly, and constraints that would prevent commitments being met are identified and removed in advance. The Last Planner System is not just a planning tool. In Sergio's framing, it is a mechanism for introducing the habits of collaboration and trust-based commitment into a team that may not previously have worked that way — habits that, over time, become the culture.

The Two Biggest Challenges in Lean Construction: Sustained Change and Competing Priorities

Lean transformation in construction faces challenges that are familiar across industries but have specific expressions in the construction context. Sergio Kemmer names two that he encounters consistently.

The first is the challenge of sustaining change over time. Lean is not a project with a defined endpoint. It is a continuous improvement mentality that requires ongoing effort to maintain, and the momentum built during an intensive implementation phase tends to dissipate unless leadership actively sustains it. Part of Sergio's work is setting expectations accurately from the start: this will take time, the results will not be immediate, and the work does not end when the initial phase concludes.

The second is competing priorities. Construction projects operate under constant pressure from multiple directions simultaneously, and the people Sergio works with are almost always managing more than one set of demands at once. Carving out the time and attention needed for lean improvement work — when urgent delivery pressures are always present — requires explicit leadership sponsorship. Without someone in a position of authority who has committed to making space for the lean work, it gets crowded out by the immediate.

Psychological Safety: The Prerequisite That Most Lean Implementations Miss

Beyond the challenge of culture change and competing priorities, Sergio Kemmer identifies a condition that he considers essential but often absent: psychological safety. The ability for people at all levels of a project to say what they think, raise problems, and challenge approaches without fear of blame or retribution.

In construction, command-and-control leadership remains common. In that environment, workers and subcontractors who observe problems or see better ways of doing things often stay silent — not because they lack the knowledge or the judgment, but because the organisational culture makes it unsafe to speak. This is the direct opposite of what lean requires. Lean depends on problems being surfaced quickly, on bad news travelling upward rather than being suppressed, and on the people closest to the work being able to share what they know without risk.

Sergio's view is that creating psychological safety is not a soft or secondary concern in lean transformation. It is a structural prerequisite. A lean system that operates on top of a culture of silence will capture only a fraction of the improvement potential available, because most of the knowledge that improvement depends on will remain unshared.

Sergio Kemmer on AI: An Enabler for Collaboration, Not a Replacement for Understanding

Asked about his experience with AI, Sergio Kemmer positioned himself as a practitioner who is actively experimenting but is measured in his expectations — and clear about what he thinks needs to happen before AI can add full value in his field.

He currently uses AI tools including Microsoft Copilot for meeting support and information-heavy tasks, and has used AI-assisted tools to streamline presentation work and automate previously laborious processes. His assessment is honest: he considers himself a beginner in this area, but one with a positive orientation toward where AI is going.

The friction he identifies is not with the technology itself but with the shared understanding required to use it well collaboratively. In a field built on team-based improvement, if some team members understand AI and others do not, the shared language and common ground needed for collaborative problem-solving is undermined. His expectation for AI in lean construction is that it will become an enabler of collaboration — making information more accessible, reducing the friction of knowledge-sharing, and helping teams work more efficiently together — rather than a tool used by specialists in isolation.

His advice for the next generation reflects this balance: read the classics, understand the core principles, and then approach AI as a friend and enabler rather than a replacement for the foundational knowledge that makes improvement work effective. Tools built on the Toyota Way and Professor Koskela's foundational work remain as relevant as they were when they were written. AI makes it easier to access and synthesise that knowledge. But the judgment about how to apply it in a specific project, with specific people, in a specific culture, is still human work.