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Cradle to Cradle Principles: Insights for Cities

Katja Hansen (pictured) is a leading practitioner, executive trainer, mentor and author in product & process innovation and infrastructure development using the Cradle to Cradle (C2C) Design framework, that forms the basis for the Circular Economy.

To say that Katja is a pioneer in the C2C methodology would not be an overstatement. In the early 1990s as a researcher with EPEA Internationale Umweltforschung and Hamburger Umweltinstitut e.V. under Prof. Michael Braungart, she co-authored formative studies in Latin America, Africa, and Europe on “Intelligent Product System” (IPS) methods for agrochemicals, nutrient recycling and natural and synthetic fibers, including for the FAO and United Nations, which set the groundwork for Cradle to Cradle® products.

Katja Hansen implements the Cradle to Cradle® Design Framework with government agencies, NGOs and companies. Her pioneering work includes the co-development of cradle to cradle initiatives in Latin America, Africa, and Europe on agrochemicals, water and nutrient recycling and natural and synthetic fibres.

She co-engineered the Carlsberg Circular Community announced at the 2014 World Economic Forum, and co-founded the Healthy Printing Initiative and co-created the Horizon 2020 BAMB project (buildings as material banks), and has been advising various agencies in Luxembourg and Netherlands governments on Circular Economy topics. Katja is the chief scientific advisor to the Cradle to Cradle NGO and a research fellow at Technische Universität München. She also lectured for the Ellen MacArthur Foundation/Bradford CE executive training courses, now continuing with Exeter University.

Katja has a degree in environmental engineering and values holistic system thinking in her projects and activities.

What is Cradle to Cradle?

The Cradle to Cradle design principles were developed in the 1990s by Prof. Dr. Michael Braungart, William McDonough and EPEA Hamburg. The Cradle to Cradle (C2C) paradigm reframes design as a positive, regenerative force — just like nature, promoting infinite circulation of materials and nutrients in cycles. Rather than seeking to minimise the harm we inflict, this paradigm shift reveals opportunities to improve quality, increase value and spur innovation. It inspires us to constantly seek improvement in our designs, and to share our discoveries with others.

“It's really important to see what good we can do rather than being less bad, which has been the driver in the environmental movement for the past 30 plus years” - Katja Hansen

The three Cradle to Cradle principles, which are normally referred to in the cradle to cradle design framework are:

1. Everything is a nutrient or resource for something else

In nature, everything is a resource for something else, and there isn't any waste, or the waste of one system is food for the next system. So being a resource for something else is a C2C guiding principle.

2. Powered by renewable energy

Our ecological systems are powered by renewable energy. So why not human engineered systems? The second principle of C2C is the productive use of solar and other renewable energy like wind power, hydroelectric power, geothermal energy, and biomass.

3. Diversity

Natural systems thrive through complexity and diversity. Human engineered principles strive for simplicity and standardisation. The third C2C principle talks about three kinds of diversity: biodiversity, cultural diversity and intellectual diversity.

What distinguishes Cradle to Cradle from the Circular Economy?

According to Katja, Cradle to Cradle, has been around for over 30 years, and its goal is to be beneficial for people and the environment. Most importantly, Cradle to Cradle is regenerative by design. Its philosophies of biological and technical flows helped to inform the iconic depiction of the circular economy: the butterfly diagram. However, unlike the butterfly diagram, Prof. Michael Braungart has often said that there should be no 'leakage' or waste.

Above: The Ellen MacArthur Foundation Butterfly Diagram Image Source

What’s stopping us from thinking in C2C principles?

Siloed thinking: The tendency to pick one problem and try to solve it. We don't normally question if that problem is the right problem to solve: was that the right question to ask? So we all have to step back and learn to question things in a different way, with the kind of imagination that children have, because we're all quite conditioned by the time we've gone through school and university and jobs.

What does 'becoming native to the planet' mean?

Nature isn't about minimisation, it isn't efficient: it is effective and abundant. Cradle to Cradle is all about abundance. Becoming native to the planet means having a broader, integrated approach that is represented in the three principles described above. A lot of our sustainability measures are all about the need to minimise and reduce, because we feel that the human burden on the planet is just becoming too much. This is an understandable response: if I'm running out of water, or running out of materials, I will try to conserve them. But we must ask: how could I do this better? How could I do this in a different, more regenerative way?

Above: from less bad to more good

What's the distinction between Cradle to Cradle and Biomimicry?

Both Cradle to Cradle and biomimicry look to nature. Nature has had the advantage of millions of years of trial and error to develop ecological systems so there's a lot we can learn. Biomimicry, which can be described as the design and production of materials, structures, and systems that are modelled on biological entities and processes, is the science of trying to figure out how nature does certain things. Some people look to biomimicry to identify specific solutions, such as how to create an adhesive that mimics geckos so we can walk up walls. However, this is missing a vital component: a systems view. It's missing connections the gecko has with its ecosystem. Katja argues that Cradle to Cradle has this systems thinking in its DNA, specifically principle 3 above.

How might Cradle to Cradle principles be applied to cities and communities?

The place to start, according to Katja, is to leverage the biological, cultural and industrial diversity of a community or city and develop solutions that integrate this knowledge.

Katja talks about a case study in Brazil, from the early 1990’s (when it wasn’t even called C2C, it was called Intelligent Product System) where nutrients were recycled out of wastewater to grow a variety of plants and cultivate fish farming. The water was purified to European water regulation standards through sunlight exposure, root systems and other natural processes. This project was successful because, of course, it had a very strong cultural component as well in the Favelas, where people were on a low income, but were proud. And so, building a facility there had impacts on many different levels. The project had two families operate a 'bio nutrient farm', which was approx. a hectare in size, but modular so it could be adapted. This gave the families income through operating the facility, harvesting produce, taking care of the livestock and also provided income to other families through value added products.

The example above shows the more diverse our systems, the more resilient our communities and cities become. We've had a tendency over the past decades to standardise, to centralise, to streamline, and in the recent pandemic we've seen that we've lost resilience in the systems. A natural comparison is one that, to scientists is very obvious: a resilient forest with a diverse population of trees and animals and shrubs is a lot more resilient to disease than a monoculture of pine trees. So we see everywhere that nature works with this resilience approach fuelled by diversity in its systems. If we take that on for our cities, diversity is a guiding principle to make cities more resilient and more regenerative.


Katja Hansen has a wealth of knowledge to share with us. Katja will join us again in a future episode to talk about the Horizon 2020 BAMB project where BAMB stands for 'buildings as material banks', a project that Katja co-created. So stay tuned.

To learn more, listen to the podcast with Katja Hansen here

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