"A building like a tree. A city like a forest." This quote by Michael Braungart & William McDonough, the two founders of the Cradle to Cradle® (C2C) design concept, describes its vision well. It promotes the idea that humanity should not see itself and its buildings as detached from nature. C2C is an approach towards the circular economy, which provides a framework for designing products and buildings whose materials flow safely in closed loops, in contrast to the linear economy's take-make-waste model. The emphasis lies on maintaining inputs at their quality level to render the concept of waste obsolete.
Eco-effectiveness for a positive ecological footprint
Research finds that we are at the tipping point wherein, for the first time,?human-made products have more mass than the total living biomass. Meanwhile, only 8,6% of resources are treated circularly, according to the Circle Economy's Circularity Gap Report. The construction industry plays a crucial role in generating non-circular mass as it is a highly material- and waste-intensive sector. Moreover, indoor air pollution, resulting from the degassing of carcinogenic mutagenic reprotoxic (CMR) materials commonly used in buildings, causes health issues such as an increase in allergies among children.
The need to transform the construction industry to provide solutions to these issues is evident. However, sustainable construction mainly addresses environmental and social problems by reducing or minimizing waste, pollution, and resource consumption. These eco-efficiency approaches focus on decreasing humanity's negative footprint on planet Earth, yet they do not provide a long-term solution.
When observing nature, we find a trend towards effectiveness rather than efficiency. For example, a cherry tree produces thousands of blossoms each year to end up with only one or two successful seeds. This is not problematic because the "waste" serves as a nutrient for both soil and animals. Moreover, during this process, the cherry tree also cleans air and water.
This raises the question of how we can transform buildings so that they mirror the effectiveness of cherry trees. How can they be designed so they are not only climate-neutral, or less harmful, but also make a positive contribution to the environment, health, and well-being of the people who inhabit it? C2C challenges most of the prevailing assumptions made by sustainable construction and building operations. It tries to address the problem at its root cause through eco-effectiveness.
Practical examples show that buildings built according to Cradle to Cradle principles outperform conventional ones during the whole carbon life cycle. For example, the flagship project "The Cradle" in Düsseldorf saves 30% of carbon emissions through healthy materials and eco-effective operation. Beyond that, Cradle to Cradle buildings can improve their surrounding's condition. For example, the Moringa Hamburg produces oxygen, reduces pollutants, and balances the climate of the Hafencity, in which it is located. The building material passport constitutes a tool to track all materials and their location in the building. If materials are then identified as hazardous in the future, as was the case with asbestos, they can be extracted more easily. Furthermore, this also reduces the embodied carbon intensity during the recycling stage by facilitating deconstruction. If a building is, for example, built in a modular way, the decomposition can in addition, be dustfree. Thus, adverse effects are already prevented during the design stage.
The biological and the technical cycle – design with the lifecycle in mind
The C2C design concept proposes that materials belong to one of two distinct cycles: the biological cycle and the technical cycle.
Those parts of buildings that are likely to end up back in the environment naturally should adhere to the principles of the biological cycle. They should be composed of renewable materials such as wood, hemp, or cotton. By containing seeds or important microorganisms instead of microplastics, they can even make a positive contribution to the environment when biodegrading.
The technical cycle is of even more importance in the construction industry as most elements in a building will not naturally enter the biological system during their use. Within the technical cycle, renewable or non-renewable resources such as glass, metal, and plastic are maintained as nutrients in industrial cycles. They must be designed for disassembly so that valuable materials can be dismantled after use to be recycled in a way that preserves or even improves their quality (upcycling). Thus, practices such as screwing, pinning, or clamping are replacing gluing or welding.
The Butterfly Diagram of the circular economy with the distinction into the biological- and the technical cycle, by EPEA and the Ellen McArthur foundation.
But how? The Principles to Cradle to Cradle® design
The holistic C2C vision of designing buildings that produce oxygen, sequester carbon and nitrogen, and distill water like trees, may sound intimidating. Therefore, there is an evolutionary approach that guides us in the ways to design safe and circular buildings inline with C2Cs 10 Principle Criteria and 9 Implementation Criteria:
The Principle Criteria:
State your Intentions
Define Materials and Their Intended Use Pathways
Integrate Biological Nutrients
Enhance Air Quality
Integrate Renewable Energy
Actively Support Biodiversity
Celebrate Conceptual Diversity with Innovation
Add Value and Enhance Diversity with Innovation
Add Value and Enhance Quality for Stakeholders
Enhance Stakeholder Well-Being and Enjoyment
The Implementation Criteria:
Do an Inventory
Integrate Innovation Finance
Integrate Diverse C2C Experienced Contractors
Integrate Systems and Application Tools
Integrate Diverse Use with Features that Apply C2C Criteria
Integrate Natural Light with Innovation Artificial Light
Integrate Renewably Powered, Healthy Mobility
Protect Occupants from Environmental Hazards
Consider Aesthetic Opinions of Stakeholders
A deep dive into each of these principles is beyond the scope of this article, but we may consider the following insights:
One central maxim is that we must get "free of" known culprits. This refers to the requirement that all materials used do not contain harmful ingredients on a chemical level. The Cradle to Cradle® Products Innovation Institute regularly updates the publicly available list of these "X-chemicals", i.e., chemicals that must not be contained in products. Only if these are omitted or replaced by "healthy" ingredients, can materials safely flow in either the biological- or the technical cycle. For example, contemporary solutions for, e.g., windows or flooring often contain PVC, including toxic plasticizers or heavy metals. This prevents adequate circulation in the technical cycle.
Another important aspect of C2C design is the consideration of the context. Considerations of, e.g., the building's location and how it will be used need to be asked to ensure it is designed in accordance with its surroundings.
At Longevity Partners, we have internalized the Cradle to Cradle® principles for the built environment and help architects, building owners, and managers increase the sustainability of construction projects and optimize buildings in operation. Through our Circular Economy service line, we address resource scarcity and climate risk by focusing on creating a positive ecological footprint.
We need to act now and move from eco-efficiency towards eco-effectiveness. Together we can design buildings according to Cradle to Cradle® standards to build a future, where buildings, in fact, are like trees, hence cities like forests.
McDonough, W., & Braungart, M. (2010). Cradle to cradle: Remaking the way we make things. North point press.
Climate Emergency Design Guide | LETI