Circular Façade Systems and Construction: Design for Remanufacturing Window Systems

Field: Engineering (Physical Sciences)

Context The “take-make-dispose” linear model has proven to be highly unsustainable during the past decades. A circular economy has emerged as a model that is restorative by design, and a response towards the high material and energy intensive linear model. However, a transition to a circular built environment implies a radical change in design and construction. Remanufacturing is one of the three product life extension strategies located in the technical cycles from the circular economy. It is an alternative to demolition, and it allows products to be longer in use, with a constant upgrade. However, for products to be remanufactured, they have to be designed according to certain guidelines, and supported by the application of circular business models. Kawneer, an American manufacturer of aluminium architectural systems and products, seeks to optimize facade systems to meet the demand for circular building products. This means that the components of the systems should be designed with product properties such as disassembly, modularity, and flexibility, which allows them to be circular. Different (re)life options, such as reuse, remanufacturing, and refurbishment, should also be taken into account from the early design stages. The RT82HI+ window system is one of the most competent products manufactured by Kawneer. However, the only (re)life option currently available is recycling. Therefore, the product is currently unable to meet the requirements of a circular building product. Objective The objective of the presented research is to evaluate the performance of the existing facade components of the RT82HI+ window system in a circular economy, and according to such, redesign towards remanufacturing and other product-life extension strategies. This is done, first, through the understanding of the relationship and dependency among the product design, development, and product-life extension, especially remanufacturing. Secondly, through an analysis of the current lifecycle scenarios of the existing components, and identification of their challenges and potentials in a circular economy. And third, through the elaboration of three different circular window systems that react upon the main findings from the analysis. Main Findings Three different designs are explored. The first one is an optimization of the existing RT 82 HI +, where only the critical aspects are redesigned. The second and third are hybrid variants that combine aluminum with wood polymer composite pro les (WPC). These three designs are assessed under the principles of DfD (Design for Disassembly), DfA (Design for Adaptability), and DfRem (Design for Re- manufacturing). Additionally, different remanufacturing, reuse, and adaptability scenarios are analyses to understand the performance of the window system in a circular economy. On the other hand, four main different types of facade systems and construction are reviewed to understand the type of attachment of the window to the construction. This resulted in a critical point because it could affect the performance of the window in terms of circularity. The results indicated improvements in different aspects. The key one was ease of assembly and disassembly, but also in terms of type of connections, and geometry of product edges. Furthermore, it is discussed how the loop is closed, and the importance of the different stakeholders involved in the facade manufacturing and construction area.