A market release of new construction materials in the twentieth century, with a simultaneous offer of their resilience and durability, affected the environmental impact of this industry [1
]. The sector nowadays is one of the main generators of waste, and is also one of the most environmentally harmful and least sustainable branches of economy [2
Prospects for the future are quite dismal. In general, we can observe the systemic, exponential growth of certain key indicators, such as population growth, concentration of CO2
in the atmosphere, and consumption of energy, water, minerals, and natural resources [3
]. Over the past 20 years, the emission of greenhouse gases (GHG), which are assumed to induce substantial environmental damage and to be a major cause of climate change, has increased significantly with the continuous growth of carbon dioxide emissions [4
]. This rapid environmental deterioration is leading most industrialized countries to reach new agreements that involve a reorientation of the production processes, according to the commitments of the Paris Agreement (2015), within the Framework of the Convention of the United Nations on Climate Change, where the measures to reduce carbon dioxide emissions were settled, starting from 2020.
In this context, the building sector plays a strategic role, being one of the most significant emitters of harmful gases, generator of waste, and consumer of resources [5
]. Modern construction materials with excellent building features show a side effect through the drastic increase in the environmental impact of this sector [6
]. Currently, one of the key aspects is to minimise waste, and therefore, waste minimising strategies, need to be considered as an integrated element of the production system [5
]. Apart from this, reuse of elements (e.g., parts of buildings) needs the deep consideration of their quality, usefulness in terms of dimensions (do they fit into a new place?), and market issues (do people want to buy used materials?). Reuse of elements presents a challenge for both architects and contractors. On the other hand, the use of intelligent material pooling is a useful framework of collaboration for the different actors in this sector [7
Besides, many countries around the world are looking for new sustainable building models, by exerting pressure on the sector to look for the reduction of environmental impact [8
]. The industry needs to implement new eco-efficiency strategies, maintaining or increasing the value of economic output while simultaneously diminishing the environmental impact [7
]. However, a current status is different; there is too much waste being produced by construction projects, with few conceptions of what to do with it. On the other hand, a resource scarcity is making us search for new technologies of waste recovery that convert the outputs of the production system into inputs of the new production [9
Industrial ecology (IE) examines the flows of materials and energy in industrial systems [11
]. The IE enables understanding how the industrial system works, how it is regulated, and what interactions it presents, to restructure it in order to make it similar to natural systems. Focusing on the connections between operators within the industrial ecosystem, this approach aims to create closed loop processes in which waste serves as an input, thus eliminating the notion of an undesirable byproduct.
The IE adopts a systemic point of view, designs production processes according to local ecological constraints, while observing its global impact from the beginning, and it tries to give them shape so that they perform as close as possible to living systems. This framework is sometimes called the “science of sustainability”, given its interdisciplinary nature, and its principles can also be applied in the service sector. According to the Ellen Macarthur Foundation, industrial ecology also focuses on social welfare supporting restoration of natural capital [11
The IE is highlighted as one of the antecedents of the CE (EMF, 2013). The latter can be defined as a type of economy with a closed flow of materials, as opposed to the traditional linear economy [13
], which, being linear, generates serious problems, such as environmental degradation and scarcity of resources [14
]. In this way, the CE will help to maintain harmony between humanity and the environment through the use of closed-circuit entry material.
In the CE there is a following flow of materials: “resources-production-waste-renewable resources” with “low exploitation, high utilization and low effluents”. The basic principles of the CE are the so-called 3R’s: reduction, reuse, and recycling [14
implies minimizing the entry of energy and raw materials by improving efficiency in production processes. Reuse
suggests that byproducts and waste from one company (or industry) can become resources for others. Recycling
, on the other hand, promotes the reprocessing of recyclable materials to convert them into new products, so that consumption of the original materials can be reduced [15
Objectives and Research Question
It seems that the CE should be treated as a production sustainable model, which is especially relevant for this sector. CE represents an industrial system based on reuse and regeneration at conceptual, organisational, and operational levels [16
]. However, we need to take into consideration the lack of indicators about circularity, which is one of the most important challenges for the future of CE [17
]. For instance, in the literature review of Lewandowski [19
], the author cites just eight studies focused on an evaluation model, and none of them took into consideration a scale for measurement of CE, which can be confirmed from a review of Tukker [20
] or Van Dijk et al. [21
]. Other references, such as Lihong and Hui [22
] or Shen and Qi [1
], are generic; for instance, the measurements focus on emission levels or energy consumption, the sustainability index [23
], or sustainability building assessment [24
]; while, Silvestre et al. [25
] are focussed on specific aspects, such as materials or supply chain management.
From this point of view, there is a lack of knowledge about what type of indicators of CE could be used [17
]. The indicators reflect the value of the variables in relation to a defined reference point [26
]. A crucial question is how to measure the application of CE principles in the building sector.
Therefore, this paper aims to build a validated scale of measurement, which is applicable to the construction industry. It allows for businesses, public administration, and governments to manage a degree of CE implementation. Thus, the following research questions should be formulated:
RQ1: How can we measure the degree of implementation of the Circular economy in building companies?
RQ2: What are the main dimensions that compose the measuring scale for the building sector?
RQ3: What are the most relevant indicators of these dimensions?
To answer these research questions, an exploratory e-Delphi study with a group of industrial and academic experts was performed followed by the confirmatory factor analysis of results. Thus, a more inductive approach was applied for the research, impacting a structure of the paper and limiting the literature review, and the content analysis more to the scale design, rather than developing hypotheses, as is usually done in positivistic and deductive research [27
The literature review highlighted a challenge, which is that we do not have a specific scale of measurement for the construction industry to guarantee its future sustainability. A general concept of the research relies on a very popular proverb in management and applied economics: “what gets measured, gets done”. By giving a consistent scale for measurement, there appear to be new opportunities for business to examine procedures/strategies (and as a result, to reward or to punish those who get responsibility) in order to achieve what is set out to perform. Through a review of literature, report analysis, application of the Delphi method, and CFA, a scale, that allowed for establishing the position of the building companies regarding CE, was built in response to the research questions of this work.
Therefore, this research helps to advance in the implementation of the CE production model in the building sector, by presenting a scale of desirable indicators of the company’s circularity thinking. This scale of measurement was generated from the analysis and review of 234 indicators. Among our objectives, one was the immediate practical application of the scale to companies in the sector. For these reasons, not only indicators from the academic world were chosen, but also indicators from top construction companies. So, 107 indicators were collected from the literature review and 127 from content analysis of sustainability reports from 10 top building contractors. To answer our research questions, a mix qualitative/quantitative methodology was used, first applying the e-Delphi technique, and after that, a confirmatory factor analysis to measure the validity of the scale.
Thus, the first contribution is a design of the dimensions that comprise the scale. What are the dimensions that experts consider most important when measuring the implementation of the Circular Economy in the construction industry? These are: Energy management, Water management, Waste management, and application of 3Rs principles that were the dimension best ranked. After that, other three dimensions: Emissions, Material, and Transition of CE were included in the scale. This measurement scale was agreed upon by the group of experts through the application of the e-Delphi technique, reaching consensus in the second round, Energy being the dimension that was most valued by the expert group.
This contribution shows that the academic and professional world are seriously concerned about the care of energy. For instance, Geng et al. [35
] and Wadel et al. [55
] highlighted the lack of absolute material/energy reduction indicators. For this reason, once one knows the dimensions, it can develop and validate specific indicators to measure them, weighting according to the experts their relevance in each dimension. This contribution is important because it allows for progress in the application of the CE, it covers the gap that was highlighted in the research on the subject [12
] and evolves from the analysis of previous works of sustainability measurement and CE in companies [2
The most ranked dimension of the scale (Energy) introduces six indicators, with Removable or clean energy consumption being the indicator most valued by experts. Certainly, companies and academics agree on the need to conveniently manage energy, increasing the use of renewable energy each year to replace those with the greatest environmental impact. This must be complemented with measures that improve energy efficiency, incorporating indicators that help it, so there is a reduction in gross energy consumption. On the other the hand, Water Management dimension is made up of four items, highlighting that the indicator Degree of recycling and water reuse is the most valued of the total of 52 that make up the scale. Therefore, the company must incorporate systems that allow for the reuse and reuse of water, thus showing the concern of the experts for the efficiency in the use of this resource, incorporating specific ratios of reuse and improvement in the efficiency of the use of the water.
Regarding to the dimension 3R’s: Reduce, reuse, and recycle would include the indicators that are related to the possibility that the product will be reused, being this indicator the most valued by the experts. Undoubtedly, the change in the way of production of the construction industry should be supported by the 3R’s, they have very resistant materials that facilitate reuse, so they have to incorporate designs and technologies that allow it.
Six indicators were incorporated to the dimension Transition to CE, where the experts’ view stated the importance of design according to CE principles, as a most valued indicator of this dimension. This shows that, for the company and academics, the design in the construction sector in accordance with the principles of the CE is fundamental for the sustainability of the sector. It is also important to promote the transformation of companies towards this new productive model, taking into consideration the environmental impact of the company.
In addition, the scale Materials included ten indicators, highlighting in this group the importance of the existence of measurements on the efficiency of the use of materials, in line with Wadel et al. [55
]. Besides, it is also necessary to incorporate channels into the organization that allow for the recovery of materials through a reverse supply chain. In addition to the relevance of the company using with responsibility the construction materials. The scale of measure includes two dimensions focused on the negative externalities of the companies: Emissions and Waste management. About the first, it analyses the environmental impact, being composed of four indicators. The carbon footprint and the CO2
level being the highest ranked, Thus, the idea of reducing the carbon footprint and global emissions of CO2
are the indicators that have been most valued by academics and entrepreneurs, specifically highlighting the necessity of control of the emissions footprint that was derived of the company’s energy consumption. Secondly, the waste management dimension raises the need to design products that can be reused in order to reduce the waste generated.
Another contribution of the work of this study is the development of a critical analysis in the construction sector on the system of sustainability indicators for this sector. The scale that has been provided can be used for the comparative evaluation, for the improvement of the environmental performance of the construction companies in multiple levels, for the identification of problematic areas in which more effort is required to advance, the cost analysis -benefit, knowing the weights of each dimension, and the final contribution that it will make to the overall valuation of the company. It will also be useful for strategic management, business investment decisions, and many other applications, allowing for the company’s stakeholders to know the position it presents towards CE. With this, a need for integration of these indicators into the company’s decision-making strategies becomes evident, in order to achieve its effective implementation.
Practical Implications and Use of the Scale
Regarding the practical application, our study provides a measurement scale applicable immediately to the construction industry. It is useful for both companies and governments, because these indicators are already being measured by construction firms, thereby guaranteeing the applicability and the possibility of using dynamic indicators that allow for comparing the degree of implementation of the CE between different periods of time. Government and public administrations are concerned about environmental issues, especially CO2 levels, generated waste and scarcity of materials. Besides, they need to assess the implementation of CE, facing new strategic regulations that are implemented or discussed e.g., by the European Union. Our work contributes by providing a scale to evaluate and establish a ranking of implementation of CE, which allows for them to make decisions about sustainability and classify buildings based on their sustainability, taking into account multiple points of view, such as the care of materials, the environmental impact, and the transition effort of the company towards a new model of production. Therefore, the transition to another model of production such as CE is not a question of social responsibility alone, but instead, has become a strategic factor that guarantees companies’ future continuity and the commitment of governments to the CO2 reduction goals.
The application of CE in the building industry will be supported by the ideas of reducing, reusing and recycling, which are the basis of the new productive systems, paying special attention to care of the resources, such as materials, energy, and water. Thanks to these new ways of production, companies will decrease their environmental impact, controlling the CO2 emissions and the waste generated. Their application will promote the sustainability of companies in the future. On the other hand, the companies’ interest groups, public administrations, and institutions seeking sustainability have the right to require from the construction companies to develop their projects in accordance with the CE principles. During the procurement process of public works, companies can be called for bids respecting the CE, so for this type of contract, a measure of the degree to which they implement CE may occur useful.
Taking into account the application of the scale, the respondant will value each indicator from 1 (very low relevance) to 7 (very high relevance). After of the evaluation, the results that were obtained from each dimension will be added and weighted by the established weight of each indicator. After that, the new values will be weighted again, according to the weight of each section. The sum of all weighted dimensions describes the final value of the degree of implementation of CE. The final weighted score will be between 1 and 7, where 1 means that a company does not implement CE at all, and 7 is a company in which CE is fully implemented.
6. Conclusions, Limitations and Future Research Lines
Building industry requires urgent measures. According to the results that were obtained in the analysis, the article contributes to evaluating the implementation of CE in the construction industry, from traditional production systems to the circular model. Energy, materials, water, and 3R are the dimensions of the scale related to resource management. Two dimensions, waste and emissions, are related to the environmental impact, with the remaining being transition to CE. Therefore, the main contribution of this paper is a design of the scale that will provide information to the company itself and its stakeholders, on the degree of long-term sustainability of the construction company, and the degree of implementation of CE.
This work shows some limitations to be considered. In the first place, a questionnaire administered via the web, as an instrument for gathering information from experts in the e-Delphi method, it has the specific limitations derived from the subjectivity of the use of this tool. On the one hand, a respondent does not go into specifics of the phenomenon under study, so it has a margin of free interpretation that can distort the objective established through the indicators. On the other hand, people who have answered the questionnaire can transmit biased information, since many items are based on the perception of the respondent. In addition, the limitations of the Delphi technique, such as the difficulties of experimental control, the recruitment to panels, the commitment of experts, the mutual attrition during the process, and the balance of consensus appear to be significant. Likewise, not everyone has available access to the web platform.
Finally, another limitation comes from the transversal nature of the research. The information has been collected at a certain time, with the exception of certain performance indicators. However, it would be convenient to analyze the effect of training and development of people on the performance of organizations from an evolutionary perspective, using long periods of time that isolate temporal phenomena and specific circumstances that may distort the result of the investigation.
The limitations and the deepening the subject of the study give rise to some future lines of research that are exposed, as follows. It is believed that it would be interesting to evaluate the implementation of the CE, not at a specific moment, but through a broader time frame, through longitudinal analyzes that observe the evolution of the variables under study. Specifically, it is considered that between 5 and 10 years is an appropriate period to longitudinally verify the effects of the practices on the performance indicators of the organization. It would also be interesting to extend the application of this scale to other industrial sectors that are in the process of CE implementation. Besides, the dissemination, the use, integration in the decision making systems, and the evolution of these indicators are new lines of research at multiple levels, which is in line with Geng et al. [35