Cradle to cradle

A new perspective on materials & design

Bas Wetzel October 2009



This page gives an overview of the cradle to cradle design concept and its application to architecture.The concept
is explained in contrast to our current way of material handling and what the approach means for designing buildings.
A number of architectural projects is discussed and compared which exemplifies the variety in which the concept
can be interpreted and what the concept means actually means in terms of sustainability. Criticism passed on the
concept is used as a starting point to clarify the discussion around the subject.

What is cradle to cradle?
The linear cradle to grave process
The circular cradle to cradle process
Cradle to cradle in architecture
Examples of cradle to cradle projects
Project comparison
Conclusions and critique

What is cradle to cradle?

Cradle to cradle is a concept for a new design
The concept proposes to change our way of thinking on materials and products from a
linear process into a circular one. Our current linear cradle to grave process causes numerous environmental problems.
Nature is destroyed for harvesting materials, valuable materials are buried or burned after use and huge amounts of
waste and toxics are produced.

The linear cradle to grave process

o Materials: Valuable materials are disposed and become useless.
o Natural resources Are spilled for energy & waste production
o Waste: Large amounts of waste materials are produced
o Toxics: Air, water and soil and people get polluted with toxic waste products.
o Energy: Fossil fuels and nuclear power create severe pollution
o Natural habitats Are destroyed for harvesting materials


The circular cradle to cradle process

In the circular process every product can be endlessly recycled as long as the products are designed and produced with
the recycling phase in mind. Because waste is turned into food for nature and industry an unlimited grow of consumption
would be possible. To make recycling possible we should separate two types of material cycles or ‘metabolisms’: the
technical and biological.
The technical metabolism recycles man made materials like plastics, concrete, metals and other
chemicals. When the different materials in the product can be separated after use it will be possible to endlessly reuse these
materials into new products without losing its material qualities.

The materials that are part of the biological cycle consist of natural materials like wood, cotton, wool and paper products. After
use they can be recycled in nature as a nutrient for plants and animals. A condition for this cycle is that the materials are not
contaminated with technical materials or toxics.The key condition for both systems to work is that the materials can be
effectively separated and recycled after use. This is necessary to prevent down cycling, which happens when different materials
are mixed into a new product. Each recycling stage will limit the possibilities for reuse until a useless product is produced after

o Materials Stay available since they are reused in an endless cycle
o Natural resources are fed with waste materials and will regrow
o Waste By separating biological and technical nutrients its easier to recycle waste. The biological nutrients can be disposed
in nature and consumed by it. Technical nu trient, if well designed can be retrieved and reused endlessly
o Toxics Non toxic additives are usually available, preventing waste from becoming toxic
o Energy sustainable energy sources makes harvesting resources and pollution unnecessary
o Natural habitats are less disturbed as fewer materials need to be harvested.

Cradle to cradle in architecture

The cradle to cradle concept is easy to explain using a single product that is made in a factory, is used and disposed after a
few years. Architecture is a different story since most buildings are unique designs that are made of products made in numerous
factories from all over the world. Closing the material cycle here is difficult task. The best way to make sure the building can be
seperated into materials that can be reused in the factory it came from is by making the building demountable and by using
locally produced materials. Mcdonough & Braungart extend the use of local building materials to using local energy and water.
A building should produce its own energy to prevent the mining and use of fossil fuels for energy production. By gathering
rainwater and purifying its own waste water a building can prevent pollution and dehydration of ecosystems elsewhere.

Cradle to Cradle gives architects an assignment which is the following:
o No toxics should be used
o All materials should separable and recyclable after the building’s lifetime
o The building should be the product of local action to ensure (ecological) diversity, expression and aesthetic preference.
o Use of local resources
o Use of local building method’s
o The building gathers its own rainwater and purifies its waste water
o The building generates its own energy or provides it to neighboring buildings if applicable

As an inspiration William McDonough visualized his ideas in a publication for the New York times called 'House like a tree '

Examples of cradle to cradle projects

The Cradle to cradle concept became known around 2002 and therefore most buildings based on cradle to cradle concept
are still in early development and often in climates different than the Dutch. The Coates architects winning entry for a cradle
to cradle house competition and the ‘flow house’ by McDonough architects are the projects closest to the
initial C2C approach as they can be seperated into their different materials after use and provide their own energy and clean
their waste water. Four European projects that were already realized were added to the them. These projects were not designed
with C2C as a starting point but contain characteristics that To come to a more detailed discussion
I'll give an overview of the different ways in which the C2C concept could be applied in architecture.


Project comparison

The projects discussed were all very different in location and concept, but all showed a different element of the Cradle to Cradle concept
The cascade park showed how easily ordinary architecture can be greenwashed into an 'Cradle to Cradle' design by simply assuming all
materials will be reused and applying some technical installations in the basement.
The 'Cradle to Cradle home' showed a design that a solar collector and garden can be successfully integrated into an architectural
design but at the same time waste a lot of energy through a glass facade
The Coutras house showed how the separation of biological and technical nutrients can be an interesting design concept that is
economical at the same time.
The Flow house showed the application of a component building system that is simple and easily demountable while remaining
the freedom of architectural expression. And how the high content of technical nutrients can be hidden behind wooden cladding.
The XX-office showed how closely demountability and cradle to cradle are related. If you can demount it into elements it becomes
a lot easier to seperate and recycle the components.
The Agrodome houses showed the difference in material use between ecological architecture and cradle to cradle architecture.
C2C is aiming for better recyclability of technical nutrients, while ecological architecture pleas for reduction of their use.

Two comparisons were made to place the different projects into perspective.The projects are placed in an order to give an impression how they
are relating to each other. The first shows how the desired separation of materials after use results into different designs.
In this they differ from combined as one sculpture up to an visible assembly of materials.
The second shows the difference in the ratio biological/technical nutrients. It seems that those buildings that were actually created with
Cradle to Cradle as a point of departure are using more technical nutrients, especially steel and glass.
The other projects that were designed from ecological, econmical and demountable motives have a larger quantity of biological nutrients (mainly wood)
This supports the observation that Cradle to Cradle more interested in recycling technical nutrients instead of using more biological nutrients.


Conclusions and critique

Critique on Cradle to Cradle architecture
The Cradle to Cradle design concept is a rather specific form of sustainability. The concept is based on the reduction of waste and the recycling of valuable
materials, while the energy problem is presented as one that is non existent as long as energy is produced locally and in abundance.
This specific focus in sustainability is the cause of a growing critique on the concept and its public popularity.
In the article:‘Cradle to Cradle is een dwaalspoor’ Friso de Zeeuw, professor 'gebiedsontwikkeling' at the TU Delft and Fred Schoorl , director of NIROV,
criticize the C2C approach. Three main issues are discussed:

(De Zeeuw:) "Hier misleidt C2C ons, het brengt ons (in de westerse wereld) op een dwaalspoor, namelijk de
monomane focus op afvalvermijding. Afgezien van een paar probleemstoffen en zwerfaval, is afval en afvalverwerking nauwelijks nog een duurzaamheidsvraagstuk.”

De Zeeuw sees the focus on waste reduction as misleading. Short of some streetwaste and toxics the problem of waste is no longer an issue.
His solution for waste is the newest generation waste ovens that can burn any material while filtering exhaust gases and producing energy.
He sees this focus on materials as hazardous to what he calls 'real' sustainable matters: energy, nature and mobility:

"Volgens De Zeeuw heeft C2C te weinig oog voor de gevolgen die de toepassing heeft voor echte duurzaamheidskwesties, die bijvoorbeeld in gebiedsontwikkeling spelen.
“Denk maar aan energieverbruik en
water, maar ook aan natuur en mobiliteit.” "

Fred Shoorl sees different disadvantages in the Cradle to Cradle concept next to the focus on materials; the scale level of the C2C approach.
The concept of returning all products to the factories where they came from may have a large impact on transport infrastructure and the energy
use and pollution that accompanies it. On the scale level there is the problem of misguidance as well.

"Volgens Schoorl dreigt door het enthousiasme er het gevaar dat we met z’n allen weer op productniveau gaan ontwerpen.
“Supergelovigen als Anne-Marie Rakhorst preken met flair, maar hebben geen oog
voor de complexiteit van duurzame gebiedsontwikkeling""

According to Schoorl the product level of the C2C approach is too small and obsolete. In the Netherlands we are already handling sustainability on the
much higher scale level of regional development, which he sees as far more effective than the product level.

Schoorl and de Zeeuw criticize C2C for its narrow view and small scale. This critique is especially important if we look at the building practice.
The enormous amounts of materials that are being used there are already recycled because of economical and environmental reasons.
For televisions the concept of returning the product to the producer may seem new, but in the building practice these problems are already taken care of.
Concrete, metal, glass, wood and roof cladding are already recycled, the main issue here is how to reduce the energy that is involved in the recycling process
,how to prevent materials from becoming polluted by toxics and to minimize the amount of new material that is required. This is a task that is mainly for the
producers of the materials and demolition companies.

For architecture there is the task to make sure to make the design demountable and to use building components in such a way that not only recycling is possible
(remelting iron and composting chipboard) but even a higher form of product re-use: building components.
By using frameworks that can be demounted into components and for example using longer wooden beams that can be retrieved intact it is possile to use these elements directly into new buildings. This way we can turn the large scale and number of elements into an advantage. Televisions are constantly changing into new models,
while building materials for the larger part stay the same. This direct recycling eleminates the need for processing the material, reducing the need for additional energy, transport and new materials that would otherwise be required in the recycling process


  1. Article: ‘Cradle to Cradle is een dwaalspoor’ Friso de Zeeuw en Fred Schoorl relativeren potentie Cradle to Cradle duurzaam building business juni 2008
  2. Book: Cradle 2 Cradle rethinking the way we make things, William McDonough & Michael Braungart, North Point Press, 2002
  3. Website: www.Cradle to