A transition towards a circular economy is proposed by initiators like the Ellen MacArthur Foundation and architect Thomas Rau, in order to preserve and enhance natural capital, optimise resource yields, and minimise system risks. A circular economy seeks to ultimately decouple global economic development from the consumption of non-renewable resources, and will eventually result in an economy of services. In this transition, the construction sector plays a major role because it is responsible for 50% of the total resource use, 40% of demolition waste and 35% of CO2 emissions.
The design of the façade system of a building which is offered as a service is essential. Assembly and disassembly of components of such a building occurs more often compared to traditional buildings, so the components and elements have to be designed so that they can facilitate this. This is especially true for the components of the façade which, due to the relatively short lifespan of a façade have to be flexible. To help incorporate circular principles in the design, a new method or tool is needed to help making design decisions and compare different alternatives. The main objective of this master thesis is to investigate the suitability of cold-formed steel components for circular façade design and to develop an assessment method to measure the degree of circularity of façades. Current assessment methods for determining the circularity of products either focus on the environmental impact or the flow of materials and protecting existing value, and not on the degree of circularity related to certain design options. Also, there is no method which focusses specifically on façades.
A circular economy is restorative and regenerative, and aims to keep products, components, and materials at their highest utility and value at all times. This is achieved by controlling finite stocks and balancing renewable resource flows, circulating products, components, and materials, and designing out negative externalities. Circular design criteria are derived from the design strategies Design for Disassembly, Design for Adaptability and Modular Design. Currently used façade systems do have the potential to be used in a circular economy, provided that the design criteria for circular use are met.
During the Case Study two designs are proposed: a traditional façade system which uses sandwich panels, and a façade system which uses façade panels designed based on a concept for roof panels developed by CFP Engineering (two alternatives). The aim of this case study is to investigate the suitability of the newly developed façade element for circular façade design. Additionally, it will serve as input for the assessment method which is illustrated later in this thesis, and set boundary conditions for the comparison of the life cycle costs and level of circularity.
The most important design parameters to determine the circularity of a façade system are: the amount of materials used, the possibility for reassembly, the environmental impact of the system, the amount of reused and renewable materials, the availability of information and the amount of toxic materials. These parameters can be measured by calculating the Façade Circularity Indicator which, as the name suggests, cannot be considered an exact value. The Façade Circularity Indicator originates by combining an existing method (Material Circularity Indicator, developed by the Ellen MacArthur Foundation) with research on Design for Disassembly (Durmisevic, 2016). A prerequisite of this method is a Life Cycle Assessment calculation. The method can be used during the design phase to help making design decisions. Based on the Life Cycle Assessment, the environmental costs of the traditional façade system are 22% higher than the environmental costs of the case study alternatives, which makes the traditional façade system less suitable for use in a circular economy. When the mass of the components is used as a weight variable, the Façade Circularity Indicator of the traditional façade system is 9 to 12% lower than that of the case study alternatives. When environmental costs are used as a weight variable, the Façade Circularity Indicator of the traditional façade system is 54 to 60% lower than that of the case study alternatives. This also indicates that the traditional façade system less suitable for use in a circular economy.
As an overall conclusion, it can be stated that cold-formed components are suitable for use in circular façade design because of their relatively low weight, low life cycle costs and the possibility to (dis)assemble them with relative ease. Furthermore, an indication of level of circularity of façades can be given based on a combination of the Material Circularity Indicator and Design for Disassembly factors.