Being one of the world’s largest waste generator, the construction industry is responsible for a train of events such as global warming, climate change, and depletion of natural resources. Materials are exhausted globally to a large extent and the waste produced in the process is not treated properly. A “take-make-dispose” or popularly known as linear economy is the process that is adopted to treat the waste currently, where large quantities of resources end up as waste after demolition of the building. This grabs our attention towards the concept of Circular Economy (CE) with the goal to potentially minimize the pending issues arising from the construction sector through recirculation of building materials. However, due to the unfamiliarity of its economic feasibility, many are still reluctant for investing in circularity as they believe circular construction to be more expensive. The main challenge is to overcome the lack of understanding of the available circular strategies and their effect on their business. Therefore, the objective of this research is to investigate how buildings can be made more circular. Furthermore, the aim is to compare the alternatives based on the life cycle costs and a circularity measure, so that stakeholders are in a better position to invest/favor circularity in general. Finally, the objective is to present a way to invest in circular projects by merging the methods used in this study. Firstly, literature review was conducted to develop a better understanding of the most important concepts in relation to this research. It reveals the need for several methods to conduct the research, and hence three methods are further elaborated. An inventory of possible circular interventions was made and categorized based on strategies and layers of the building. The methods discussed were applied to a case study. The application of interventions on the base case intends to gradually increase the circularity of the building. This gradual increase in circularity calls for a comparison of a traditional building with its circular twin. Based on the analysis, it can be concluded that a comparison as such can help in a parallel tracking of both circularity level and life cycle costs of a building, which in turn aids in taking both the factors into account for decision making. Thus, both the costs and circularity of a building are quantified. The main findings are: A building can be made more circular by searching for circular activities that can replace a non-circular activity by using a circular strategy framework- in this case, R-strategy was used. The application of circular activities or interventions can be categorized layer-wise to carefully examine the impact of the activity on the circulatory level and costs associated with the building. This can be done by diving the building into different layers- in this case, Stewart Brand layers was used. The circularity of the building is to be increased gradually. Further, several alternatives can be generated to analyze the best-case scenario that can justify both the circularity and cost of a building. This is done by using a circularity measure and life cycle costing- in this case, material circularity index and discounted cash flow analysis were used respectively. Finally, the results can be analyzed by quantifying both circularity and cost. This makes sure circularity in a building is not compromised for the costs associated with the building. This way, stakeholders are better aware of the opportunities and can make better decisions in selecting circular projects which could lead to enhance the acceptance of circularity within the building sector.

Recently, sustainability is becoming a more important aspect in the building sector. The use of performance-driven approaches are progressively growing interest among architects and engineers. Proper design of a large span roof shading system can positively influence the micro-climate of the space underneath, representing a significant source of daylight and reducing the building energy demands. To support the decision making process and steer towards high-performing solutions, the adoption of computational design processes has the potential of being a fast and reliable approach. This project was undertaken to propose a computational workflow and evaluate its effectiveness as supportive decision-making tool from the early design stage of large roof shading systems. The proposed Computational Design Exploration (CDE) is adopted to evaluate three different concept alternatives in terms of daylight and thermal performances. Based on the visualization and analyses of the data, the best performing morphological features of the three alternatives are identified and the design is refined to create an optimal fourth concept. In a second phase, the Computational Design Optimization (CDO) workflow is applied to obtain high performing solutions in terms of daylight objectives, by varying geometrical and material inputs. 50 configurations are selected as optimal. The post process of the CDO consists of a second CDE, in which the selected samples are evaluated in terms of energy performance. The final shading system is chosen by identifying the input settings that allow the lowest energy consumption. As result, the daylight requirements are fulfilled and the thermal properties are used as final decision criteria. The steps described in the CDE and CDO workflow are followed through the combined use of a parametric modelling tool (Grasshopper) and a multidisciplinary design optimization platform (modeFRONTIER). Post-processing tools are adopted to help the identification of interaction effects of the variables on the performance targets. By a series of data visualizations and sensitivity analyses, it is determined whether the final optimal selected design configurations improve the visual and thermal performances. The most important identified trends and variables are used as main inputs to produce a more structured and integrated computational workflow. The final proposed workflow is meant to be a versatile method to assist the designer in the decision making process, yet maintaining his/her autonomy of judgement. Future research is needed to prove the validity and effectiveness of the proposed workflow. The integration of other design variables and performances objectives could lead to an holistic method, suitable for every kind of multi-objective design problem.