Danielle Densley Tingley

Applying Circular Economic Principles to Reduce Embodied Carbon

This chapter explores the connections between the circular economy and the reduction of embodied carbon. Circular economic approaches focus on maintaining the value of materials for as long as possible. A circular economy seeks to keep materials in circulation, removing the concept of waste from the system and the need for material extraction from primary sources. In a completely circular economy, all ‘waste’ outputs would equal system inputs. If the built environment is thought about in this way, as a system, then the inputs are construction materials, and these materials accumulate in buildings, which can also be thought of as the stock. Demolition waste is the output flow of materials in this system. This concept can also be extended to embodied carbon. Construction materials are input flows of embodied carbon. These emissions are new to the system. The adoption of circular economic design approaches that facilitate longer building lifetimes, greater component and material reuse can reduce the input flow of embodied emissions and ensure already expended embodied carbon remains in stock. This chapter commences with a review of the key literature on the circular economy in construction in general terms and provides an overview of four related design strategies: building reuse, material reuse, design for deconstruction and design for adaptability. A series of ‘good practice’ case studies illustrate the respective strategies across a range of structural types. Each case study is used to provide practical insights on project processes, drivers, enabling conditions and the perceived benefits and challenges of adopting circular economic approaches. These insights are drawn from semi-structured interviews with members of each design team, supplemented by supporting literature. The chapter concludes by drawing out common lessons of how circular economic approaches can contribute to the delivery of a low carbon built environment.

Minimizing the Environmental Impact of Steel Structures

Within the construction industry there is an increasing awareness of the importance of sustainable design. When considering the structure, the main focus will often be on minimising the carbon embodied within it. This paper discusses a strategy, design for deconstruction, aimed at minimising the embodied carbon of steel structures. This design tactic facilitates steel elements being reused after their first life. Following a PAS2050 methodology, the environmental impact of the element is spread out between the numbers of potential lives. This not only reduces embodied carbon but also lessens the exploitation of natural resources. The potential energy and carbon savings that can be accrued are estimated and the web-based tool, Sakura, used for these calculations is presented. This work culminates with an overview of projects that are already pioneering this approach in steel.