Circular Economy Practices Used in the Built Environment: History
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The linear economy model that is generally practised in the construction industry is one of the main reasons hindering the achievement of sustainability in construction. Alternatively, the Circular Economy (CE) model is becoming a promising approach to achieve sustainable construction, in which materials and products are circulated at their highest economic value and, thereby, contribute towards mitigating the negative economic, social, and environmental impacts of the construction industry. For a successful transition towards CE in the construction industry, it is important not only to understand CE practices that could be implemented across different stages of the life cycle of construction projects, but also to understand how a particular practice relates to another at those stages.

  • circular economy practices
  • construction industry
  • rational decision making
  • life cycle
  • sustainable construction

1. Introduction

The construction industry is a complex and dynamic industrial sector [1] in which the majority of products are unique, produced majorly on an outside site, with the involvement of different stakeholders. Given that the construction industry is the largest contributor to the economies of many countries [2], it is not surprising that the industry consumes the majority of natural resources and raw materials for production [3,4]. As confirmed by Norouzi, Chàfer [5], the construction industry is responsible for half of all raw material consumption and 36% of total energy consumption, globally. On the other hand, Zhang, Han [6] pointed out that, while natural resources are used to construct new structures, some ageing structures are demolished, and a large amount of waste is released into the environment. According to Benachio, Freitas [7], the linear economic model practised makes the construction industry responsible for 25% of all solid waste produced in the world. Kirchherr, Reike [8] opined that the growing demand for construction products resulted in material scarcity and growing environmental concerns. Thus, it is imperative that the construction sector converts from linear models to sustainable models [9,10,11,12]. Ossio, Salinas [13] found that changes in the construction sector consistent with a circular economy (CE) model would be ideal for becoming more sustainable.
As defined by the Ellen MacArthur Foundation (EMF), CE is an industrial system which is restorative or regenerative by intention and design concerning both technical and biological cycles [14]. CE has been implemented gradually across many industrial sectors at different levels, since its inception in the late 1990s [15]. Applying CE in the construction industry is termed as ‘circular construction’. Kubbinga, Bamberger [16] describe circular construction as “the development, use and reuse of buildings and infrastructure, without avoidable depletion of natural resources, pollution of the environment or negatively impacting ecosystems”. According to Ghisellini, Ripa [17], CE focuses on the entire supply chain in the construction industry with a circular vision and, thereby, achieves sustainability in construction [10]. The EMF [18] has emphasised that the built environment can benefit from savings of natural resources and energy to a considerable amount by applying CE. Furthermore, the construction industry has great potential to create value and leverage CE implementation because of the significant environmental, social, and economic impacts created through the implementation [19]. However, the construction industry is still in the early stages of adapting to CE, despite the vast benefits it can generate through the transition [13,20].
A systematic review carried out by Osobajo, Oke [21] on CE application in the construction industry revealed that approximately 64% of the research reviewed was related to construction materials and resources, with 34% and 30% related to resource reuse and waste management, respectively. Agreeing with this, Ogunmakinde, Sher [22] mentioned that the construction industry still lacks CE initiatives related to many aspects of the construction life cycle and focuses only on major aspects like resource handling and waste management. While waste management and resource handling have gained significant attention in the literature related to CE in the construction industry [10], limited attention has been given to other areas like design, supply chain management, land use, energy efficiency, risk management, cost management, and health and safety management, which are considered to be critical areas in a construction project [21]. The design of a construction project is critical as it is the focal point that decides the future performance of the completed project [23]. Therefore, how CE can be integrated into the design process needs to be studied in depth. Nasir, Genovese [24] opined that, since the construction supply chain involves multiple entities, it is worth considering how CE can be integrated into it. Investigating how CE initiatives can assist the efficient use of energy is essential as the energy requirement of the construction industry is significantly high [7]. The effective management of cost and other uncertainties is critical for the successful completion of a construction project [21]; accordingly, it is important to focus on CE initiatives in these areas. Less focus given to the aforementioned critical areas would hinder the successful transition towards CE in the construction industry [23], as a successful transition requires a comprehensive understanding of the entire construction process and a focus on possible CE practices at each stage of the construction life cycle [11,25,26].
CE practices control resource intake, waste emission, and energy outflows through slowing, closing, and narrowing loops [27]. As opined by van Stijn and Gruis [28], the transition towards a circular construction industry necessitates alterations of current practices that are based on the linear model. In general, projects are organised into stages or processes, referred to as the project life cycle. Due to the unique and complex nature of the construction industry, it has a lengthy life cycle which involves distinct activities in each stage [29]. The life cycle perspective is paramount in CE implementation as the activities at one stage may be highly related to the decisions taken at another stage [30]. Hence, focusing on individual CE practices or a single life cycle stage without identifying the relationships among CE practices throughout the life cycle may not optimise CE implementation within the construction industry as a whole [31].

2. Circular Economy (CE) Practices Used in the Built Environment (BE)

Circular economy is currently a prime focus area of many industries including construction. The implementation of CE in the construction industry is critical for achieving sustainability [21,28,33]. A report from the World Economic Forum (WEF) [34] suggests that the implementation of CE in the construction sector could result in savings of over USD 100 billion per year due to increased productivity. Similarly, Mhatre, Panchal [11] opined that the CE concept has the potential to reduce the carbon footprint of the construction industry, being a sound alternative to intake less natural resources and produce less waste [22].
CE can be implemented in four different systematic levels: nano, micro, meso and macro. In the construction context, all types of materials and components are in the first level (nano), all types of structures including buildings and infrastructure are in the second level (micro), industrial areas are in the third level (meso), and cities and countries can be considered to be the fourth level (macro) [19]. To successfully implement CE in the built environment, practising CE in parallel at all four implementation levels is essential [11,19,21].
The use of circular practices facilitates the transition of the construction industry towards CE [35]. Even though circular concepts related to the construction industry are discussed frequently in the literature, the practical application of the same remains negligible due to the lack of known standard practices [7,35,36]. Similarly, van Bueren, Leenders [37] identified the lack of existing standard practices as a barrier to adopting CE concepts in the construction industry.
In addition, Ababio and Lu [38] identified that CE-related terms have been used inconsistently in the literature, which can also be seen as a barrier to the successful implementation of CE in the construction industry. For instance, some authors name CE practices as ‘CE principles’ [39], while others refer to the same as ‘CE aspects’ [36] or ‘CE strategies’ [35]. Since the CE literature has used terms in contradictory ways, the dictionary meanings of the terms were explored to proceed with a proper term in the current study. According to the Oxford Dictionary, ‘principle’ means ‘a fundamental truth or proposition on which others depend’; ‘strategy’ means ‘a plan, scheme, or course of action designed to achieve an overall aim’, and ‘practice’ means ‘an activity or action considered as being the realisation of a theory’ [40]. The quoted definitions exhibit a clear difference between the terminology and place the term ‘principle’ at the high level in the hierarchy of CE-related terms. Thus, the term ‘principle’ is not appropriate for use in the current study, which is only associated with CE implementation in the construction industry. Strategies are more from an organisational perspective, and they refer to an overall plan to achieve CE which may contain practices as part of it. Since this study majorly looks at how CE could be implemented within a construction project domain practically, it was decided to utilise the term ‘practice’ throughout the study, aligning with Benachio, Freitas [7] and Asante, Faibil [33].
The concept of CE in the construction industry is studied along with the life cycle stages of a construction project. Guerra, Shahi [41] opined that CE practices can also be implemented in different stages of the life cycle of a construction project. Furthermore, CE practices in different life cycle stages can be related in different ways, and sometimes the absence of one will create no existence of others at a different stage [42]. Hence, classifying CE practices from the perspective of the construction life cycle and identifying relationships among practices are significant [7,43]. The life cycle of a construction project starts with the design phase; continues at the manufacturing phase, construction phase, use phase; and ends with the end-of-life phase [7,44].

This entry is adapted from the peer-reviewed paper 10.3390/buildings14030653

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