The Cradle to Cradle concept was developed by Michael Braungart en William McDonough and aims to transform the current negative impacts on mankind itself and on the natural environment, into a positive one. This can be achieved by closing material cycles (biological and technological), by avoiding the incorporation of toxic elements in materials and by enhancing biological diversity and human well-being, instead of endangering them. In short, product designs should be made with equality, economy and ecology in mind.
The current scientific approaches to this problem, like Industrial Ecology, Ecological Design and Integral Chain Management, only try to minimise the environmental impact of human activities with the objective of reaching a neutral influence on the environment. The Cradle to Cradle concept, however, aims to replace the negative influences by positive ones. As a result the current problematic system will no longer be sustained, people will not have to be activated by negative messages and, lastly, the impact of many small but accumulating sources of pollution, which have irreversible effects, will be prevented.
In the C2C concept little attention is paid to the current energy problems. According to the authors, these problems can be solved by the use of solar energy. This argument is supported, among others, by the recently published plans for the Desertec network. This plan proposes the installation of a network of Concentrated Solar Power plants in deserts, which, in collaboration with current sustainable energy solutions such as hydropower plants and windmills, would be able to provide in all of our energy needs. Therefore, energy production and use is in the end not a technological problem, but a political and financial one.
Some materials, on the other hand, will be depleted within a few decennia if we continue with the current rate of exploitation of the earth’s resources. Because of this problem, this research has been focused on the materialisation of the Cradle to Cradle concept.
In order to do this, a number of principles and criteria were distilled from the book by Braungart and McDonough, from the scientific background of the Cradle to Cradle concept and other, similar, sustainable building concepts and from the criticism from the scientific community on the C2C concept.
The principles considered, all consisting of one or more criteria, are: “exclusion of toxic elements”, with criteria based on LCA studies of building materials, “closing the material cycles”, with criteria concerning biological degradation and the recyclability of materials belonging to the technological cycle, “ecological and social aspects”, where biological diversity and human welfare are the criteria, and “future value” concerning long-term aspects such as the sustainable exploitation of renewable resources.
Using these principles and criteria, a practical tool has been developed, which can give a relative rating that shows to what extent a building material is compliant to the materialisation aspects of the Cradle to Cradle concept.
The tool is set up in such a way that for each principle, a rating in percentages is scored which is then used to calculate a final result for the material, using weighing factors. The final score will be 0% for a material which is not compliant at all and 100% if it is fully compliant.
The tool differentiates between materials in the technological cycle, biological cycle or a combination of both, so the criteria used in the calculation, are only those that belong to the cycle applicable to the material. Because some criteria within a principle are dependent on criteria in another principle, the influence of the criteria on the final score may vary, depending on which cycle the material belongs to.
The developed tool was used to calculate compliancy ratings of materials used in the construction of a new Dutch single household reference dwelling. This is a standardized, theoretical building, published by an agency of the Dutch government. When considering the different building components, it was concluded that the lower scoring parts of the reference dwelling were the foundation, interior walls, faÃ§ades and floors. From these components, the faÃ§ades were chosen to investigate further with regard to Cradle to Cradle possibilities.
The next phase of the research consisted of analysing the building materials that are commonly used in the Netherlands for faÃ§ades of new Dutch single household dwellings, with the aid of the developed tool. This analysis showed that no materials are 100% compliant to the Cradle to Cradle concept, but that several materials, such as adobe bricks and some thermally or chemically modified wood types, score above 90%.
Using these results, three faÃ§ade concepts where developed (dry construction, timber frame construction and a green faÃ§ade) and for each of them the average compliancy rating was calculated. Although there was no obviously better construction method, it was concluded that with an average rating of about 80%, all three concepts scored significantly better than the faÃ§ade of the reference building, which scored a mere 55%.