# Implementing Circular Economy Strategies in Buildings--From Theory to Practice
###### Abstract  
Population growth, along with a rapid urban expansion, is imposing a heavy pressure on the planet's finite resources. It is widely acknowledged that the building industry consumes large amounts of raw materials while generating waste and emissions. To set apart economic growth from environmental repercussions, the Circular Economy (CE) arose as an innovative paradigm that can offer a fast-track towards a sustainable built environment. This paper will tackle a research gap that academia and policymakers often highlighted, which is how can we apply CE to assets that are predominantly meant to be demolished and their resources wasted when they reach their end-of-life. Globally, the paradigm aims at erasing the waste concept, relying on renewable and regenerative sources, and keeping the materials, components, and systems in use at their highest value as long as possible. The concept's implementation would attempt to consider the built environment as a closed-loop system wherein resources are viewed as a scarce commodity. Although the CE seems straightforward, translating the circular thinking to the building level might be a hardship. The following paper will attempt to shed light on how to promote CE in buildings that will ultimately lead to healthier, more efficient, and more sustainable cities on a broader scale. The proposed framework considers CE implementation strategies throughout the building's lifecycle and mainly deals with three innovative aspects: wise resource management, building design approaches, and digitalization of the building industry. In this sense, this study will explore these game-changing factors that are considered paramount to concretize the concept in practice and provide a smooth pathway for CE uptake in buildings.  
circular economy; circular building; implementation strategies; design strategies; circular resource flows +
Footnote †: journal: Applied System  
the system [8]. Recent studies have focused on recycling Construction and Demolition Waste (C&DW) with little consideration on the reuse of products, resulting in the reduction of reclaimed materials [9, 10]. The avoidance of C&DW is becoming more adopted, whereas further studies must be conducted mainly at the design stages to ensure better end-of-life scenarios [11, 12, 13]. While, typically, contemporary buildings are not designed for deconstruction [14, 15, 16, 17], the concept of reusing their assets after their end-of-life should be considered for achieving higher levels of environmental performance with less material input [18]. Others have also stressed the significance of the building stock, which represents the most critical part of the produced (human-made) wealth of industrialized societies [19, 20], and have underlined the urgent need to decrease material use and increase the quality and durability of the building stock as a resource [2].  
Nevertheless, implementing CE strategies in buildings promises to be hindered by the ambiguity surrounding the concept. Despite the fact that the research output contributing to the development of a circular built environment is considerably increasing [21, 22], there is still a lack of a thorough study that entails various facets of CE in buildings [7]. The present research will describe CE background, strategies, and approaches that can be applied in the construction industry according to recent studies, in an attempt to link theory to practice and provide better insights on the concept's uptake at the building level.