2. Circular Economy
This chapter will discuss the change from a linear economy towards a circular economy. It starts with clarifying the definition, principles and characteristic of a circular economy. Subsequently will multiple drivers for change be mentioned, explaining why this change towards a new type of economy is needed. Above all will this chapter focus on circularity in the built environment.
2.1 Definition of Circular Economy
Research to our current economy and its problems is not something new, already in 1972 a report called ‘The Limits to Growth’ got published by the Club of Rome. This report explained the unsustainable relation between the economic growth and the available natural resources on earth (Rood, 2015). This report was not even the first report about the limits of our earth. In 1798 Reverend Thomas Malthus published an essay about the limits of human populations because of environmental constraints like the exhaustion of the available food supply. The availability of resources is essential for all biological and social-economic activities (Lovejoy, 1996). ‘Our Common Future’ is another considerable report, written by the World Commission on Environment and Development (WCED), published in 1987. They introduced the term ‘Sustainable Development’ and defined it as: ‘’Development that meets the needs of the present without compromising the ability of future generations to meet their own needs’’ (World Commission on Environment and Development, 1987, p. 44). This sounds wise but it is doubtful if our current way of living is in line with this definition. The circular economy is also related to multiple schools of thought, like the functional service economy, cradle-to-cradle design philosophy, biomimicry, industrial ecology, Blue economy and Regenerative Design. These schools of thought gained prominence in the 1990s (Ellen MacArthur Foundation, 2015). Section 2.2 will elaborate among other the relation between characteristics of the circular economy and these schools of thought. The circular economy is a holistic and innovative approach of a possible future economy, but an unambiguous definition of the circular economy is missing.
According to an article written by Kirchherr, Reike and Hekkert (2017) has the circular economy recently gained momentum among scholars and practitioners, but many different definitions are used for this new type of economy. They have gathered in total 114 definitions of a circular economy with the aim to create transparency concerning the current understandings of a circular economy. The findings show that the aspects 'reduce’, ‘reuse’ and ‘recycle’ are seen as most important. Notable is the fact that there are only a few explicit linkages between sustainability and circular economy. The main aim of a circular economy according to all these definitions is economic prosperity and environmental quality, impact on social equity and future generations is barely mentioned (Kirchherr, Reike, & Hekkert, 2017), but this does not mean social value is not included in a circular economy. Moreover, many researches prove the added social value of a circular economy (Wijkman & Skanberg, 2016; Bastein, Roelofs, Rietveld, & Hoogendoorn, 2013; Ellen MacArthur Foundation, 2015a; Green Alliance, 2015).
The most prominent definition of a Circular Economy has been provided by the Ellen MacArthur Foundation. Many reports refer to their definition and also in the analysis of Kirchherr et al. (2017) is this the most employed definition. The Ellen MacArthur Foundation is a global thought leader of circular economy and has the aim to accelerate the transition from a linear to a circular economy. Also this study will use the definition of circular economy defined by the Ellen MacArthur Foundation.
‘’The circular economy is an economy that is restorative and regenerative by design and aims to keep products, components, and materials at their highest utility and value at all times’’ (Ellen MacArthur Foundation, 2015, p. 46).
Figure X on the next page clarifies the definition of the Ellen MacArthur Foundation. This figure is called the butterfly, the middle represents a linear economy and the loops around the circular economy. With ‘restorative’ they refer to the technical cycle on the right side and with ‘regenerative’ to the biological cycle on the left side. If the product does not serve its purpose anymore, it is important to make use of the smallest possible loop to keep products at their highest utility. Repairing a product should be way more efficient than recycling a product for example. This is endorsed by Potting et al. (2016), they describe 10 circular strategies in a certain priority order. A rule of thumb with these strategies is that a more circular strategy will decrease environmental pressure and the amount of raw material that is needed. The first step is using materials efficient by recovering and recycling. The second step is increasing the lifespan of products and components by repurposing, remanufacturing, refurbishing, repairing, and re-using. The most circular efficient step is to use and produce products more efficient by reducing, rethinking and refusing.
Tabel X (Potting, Hekkert, Worrel, & Hanemaaijer, 2016)
Increasing circularity Use and produce products more efficient R0 Refuse Making a product superfluous by abandoning its function or replace it with another product
R1 Rethink Increase product usage by sharing or multifunctional usage
R2 Reduce Produce products more efficient by using less (raw) materials
Increasing the lifespan of products and components R3 Re-use Re-use of products that are technical alright by another user
R4 Repair Repairing and maintenance increase the lifespan of a broken product
R5 Refurbish Refurbish and upgrade old products to increase the lifespan
R6 Remanufacture Using components of discarded products to produce new products with the same function
R7 Repurpose Using (components of) discarded products to make a new product with a new function
Efficient use of materials R8 Recycle Process materials into materials of the same quality or lower quality (downcycling)
R9 Recover Using the energy of burning materials (energy recovery)
The next section will zoom in on the principles and characteristics of a circular economy to get a better understanding of this new type of economy.
2.2 Principles and characteristics of Circular Economy
The Ellen MacArthur Foundation has established three principles and several characteristics where the circular economy is based on. They also distinguish two cycles, a biological cycle and a technical cycle (see figure X). The biological cycle contains flows of renewable materials, only this cycle includes consumption. The management of stocks of finite materials is described in the technical cycle. The three principles are explained below.
– Principle 1: Preserve and enhance natural capital by controlling finite stocks and balancing renewable resource flows.
Dematerializing is the starting point for this principle; if products are not really needed, resources are getting saved by simply not making these unnecessary products. In case resources are needed, these have to be chosen wisely; make for example use of renewable energy instead of fossil fuels (Ellen MacArthur Foundation, 2015).
– Principle 2: Optimize resource yields by circulating products, components, and materials at the highest utility at all times in both technical and biological cycles.
Products should be designed in such a way that these products, its components or its materials can stay in the system. The smaller the loop the better it is; maintenance is better than recycling for example (Ellen MacArthur Foundation, 2015).
– Principle 3: Foster system effectiveness by revealing and designing out negative externalities.
Trying to minimize the damage to systems; such as pollution, climate change and other negative effects related to resource use (Ellen MacArthur Foundation, 2015).
There are also some characteristics that describe the circular economy in more detail. These characteristics give a comprehensive understanding of a circular economy.
– Waste is designed out. Waste does not exist in a circular economy. Technical materials will be recovered, refreshed and upgraded and biological materials can be returned to the soil (Ellen MacArthur Foundation, 2015).
– Diversity builds strength. In a fast changing world is diversity a key driver of versatility and resilience. Biodiversity and different scales of businesses are other examples of diversity (Ellen MacArthur Foundation, 2015).
– Renewable energy sources power the economy. The energy that is still needed within the circular economy should be renewable energy, for example wind or solar energy. This will decrease resource dependence (Ellen MacArthur Foundation, 2015).
– Think in systems. It is crucial to understand how parts influence one another within a whole. The links and consequences have to be considered all the time (Ellen MacArthur Foundation, 2015).
– Prices or other feedback mechanisms should reflect real costs. The costs of negative externalities of a product should be taken into account. The current lack of transparency of these costs makes the transition to a circular economy difficult (Ellen MacArthur Foundation, 2015).
Djoegan and Reek (2016) related in their joint master’s thesis some of these characteristics to different schools of thought. They demonstrate with their research that the characteristics of the circular economy are not something totally new but can be directed to already existing schools of thought. The circular economy can be seen as a combination of these schools of thought.
(Djoegan & Reek, Supply Yourself, 2016)
Having a clear understanding of the circular economy and the thoughts behind it brings us to drivers of a circular economy. Why is change actually necessary and for what kind of problem will a circular economy be the solution? Next section will discuss this.
2.3 Drivers of Circular Economy
The linear model of production and consumption, including a take-make-dispose pattern, dominates our current global economy. Since the mid-20th century consumptive and extractive economies accelerated quickly resulting in more and more negative externalities (Ellen MacArthur Foundation, 2015). These trends tend to aggravate due to a changing world population. According to the World Population Prospects The 2017 Revision published by the United Nations will the world population increase by roughly 83 million annually. In 2030 the total world population is expected to be 8.6 billion, in 2050 9.8 billion and in 2100 11.2 billion (Department of Economic and Social Affairs, 2017).
This growth will result in a major need for products and materials and will have a big influence on our resources, but this need will be enlarged by an exponential growing middle class in developing countries (Ellen MacArthur Foundation, 2013b). The total middle class is expected to more than double in size, expanding by 2.4 billion people from 2015 till 2030, resulting in a total of 5.4 billion people (Kharas, 2017). This positive economic evolution in developing countries will contradictory increase the negative externalities. These negative externalities include environmental consequences related to the linear economy, like climate change, decrease in the diversity of life on Earth, decrease in natural capital, land degradation, and pollution of the ocean (Ellen MacArthur Foundation, 2015).
Other drivers for change towards a circular economy are for example economic losses and structural waste. The linear model is extremely wasteful and creates a lot of value destruction. The relatively low resource prices compared to labour costs boosted the wasteful system of materials. Reusing will never have the priority when obtaining new input materials and disposing old materials is cheaper and easier. This creates a lot of waste. In 2014 we created in the European Union 2503 million tonnes of waste according to Eurostat (2018). In the Netherlands it was 7.901 kg per inhabitant. The problem of the current recycling system is the fact that most materials are getting downgraded, also called ‘downcycling’. The quality of the recycled material becomes less than the original material (Rood, 2015). Current way of downcycling in Europe captures only 5 percent of the original raw material value (Ellen MacArthur Foundation, 2015).
Price and supply risks occur due to a growing awareness of finite resources and are another driver of change. High resource price volatility creates uncertainty and can discourage businesses from investing, this can dampen economic growth. Related are the supply risks. Many countries are dependent of imports because these areas possess few natural deposits of non-renewable resources. The European Union for example is importing six times more material than exporting. We are highly dependent on other countries (Ellen MacArthur Foundation, 2015).
The linear system is related to a whole set of negative environmental consequences, like climate change, loss of biodiversity and natural capital, land degradation, and ocean pollution. Besides the fact that the environment becomes increasingly important, the circular model decouples growth from the consumption of finite resources. Growth in a circular economy is not depending of finite resources.
The advances in technology enable us to change towards a circular economy. Technology improves efficient collaboration and knowledge sharing, makes better tracking of material flows possible, makes reverse logistics easier and increases the use of renewable energy (Ellen MacArthur Foundation, 2015).
The built environment has an enormous influence on these drivers. Also for the Dutch government is the building sector one of the sectors with the highest priority (The Ministry of Infrastructure and the Environment and the Ministry of Economic Affairs, 2016). Next section will zoom in on circularity in the built environment.
2.4 Circular Economy in the Built Environment
The drivers for change mentioned in the section above will have a significant impact on the building industry. This industry is for 90% depending on virgin raw materials and for 96% on fossil fuels (Circle Economy, van Odijk, van Bovene, 2014). Price and supply risks will become tangible in the building industry, especially when the world population is going to increase as expected. Besides the drive to change is there also an environmental need to change. The global building and construction sector has an enormous environmental impact. According to a research of the United Nations Environment Programme (2014), UNEP, takes one third of the global energy end use place within buildings and another 10% can be assigned to the manufacturing of building materials. This sector is highly material intensive, 40-50% of the total flow of raw materials worldwide can be assigned to building products and components (Antink, Garrigan, Bonetti, & Westaway, 2014). The built environment is one of the largest and most resource intensive value chains in our economy (Ellen MacArthur Foundation, 2015). It is also the biggest contributor to climate change; buildings produce 30-40% of total global greenhouse gas emissions. During this phase it is also using 12% of the global water use, but this amount will increase significantly when also the water demand for the production of building materials is included. The waste produced in this sector accounts for 30-40% of the total waste production (Adams, Osmani, Thornback, & Thorpe, 2017; Vos, Wullink, de Lange, Van Acoleyen, van Staveren, & von Meijenfeldt, 2016; Sante, 2017; Circle Economy, van Odijk, van Bovene, 2014). This is in line with the numbers of the Dutch government. In 2010, 60 million tonnes of waste has been created, the building sector was responsible for approximately 24 million tonnes (Rijkswaterstaat, 2013). Lehmann (2011) even suggests that the construction sector uses more materials, produces more waste and contributes less to recycling than every other sector in our economy.
The positive side is that the recycling rate of this sector is 97%. Only 2% becomes land fill and 1% is incinerated. The down side is that most materials are getting downgraded, also called ‘downcycling’. The quality of the recycled material becomes less than the original material (Rood, 2015). E.g. stony rubble. The vast majority of the waste is stony rubble, only 2% of this waste stream will be used to make new concrete, the rest ends up under roads. This means that still 98% of the gravel in new concrete is virgin material (Circle Economy, 2015).
According to the Ellen MacArthur Foundation (2017) could cities be uniquely positioned to stimulate the transition from a linear to a circular economy because of a high concentration of resources, capital, data and talent. Local value loops can arise in circular cities with maker-labs, collective resource banks and digital application to broker the exchange of materials. Due to the geographical proximity of users and producers, reverse logistics and material collection cycles could be more efficient. Reuse, sharing and collection based business-models are more likely to occur in a city because of a sufficient scale for effective markets (Ellen MacArthur Foundation, 2017). Current scientific literature and researches tend to focus on circularity at city level (macro-level) and material level (micro-level), but only little research is at building-level (meso-level). Research at this fundamental level is critical for understanding and applying the circular economy in the built environment (Pomponi & Moncaster, 2016). Section 2.5 will focus on circular buildings.
2.5 Circular Building
The environmental impact of our built environment as described above shows the opportunity of circular buildings in a circular economy. Just like the definition of the circular economy discussed in section 2.1, is also the definition of circular construction or circular buildings unambiguous. ABN AMRO describes a circular building and demolishing sector as a sector where buildings are designed to be demountable and having a maximum lifespan. A building should accommodate different functions and it should not be difficult to make esthetical or technological adjustments. During the user phase only renewable sources has to be used (Circle Economy, van Odijk, van Bovene, 2014). ING (2017) speaks about circular construction, this involves the entire construction supply chain. All stakeholders try to minimize the use and maximize the reuse of buildings, building components and/or building materials from the beginning of the construction process (Sante, 2017). Green Deal Circulaire Gebouwen (GDCG) is a collaboration between the Dutch government, companies and institutions with the aim to translate the circular economy principles and ideas into buildings. In the cooperation agreement they define a circular building as:
‘’A building that is designed, developed, managed and used according to the circular economy system, a central aspect of the building is a decrease in the use of raw materials and maximizing reuse. The aim is to use as few new raw materials as possible and where products, raw materials and systems are used, keeping them as long as possible (on a high value level) in the construction chain’’ (Green Deal Circulaire Gebouwen, 2015).
The result of this collaboration is a material passport and a subsequent user manual. In this user manual they define a circular building a bit different: ‘’A building that creates maximum value with the minimal use of virgin materials and other raw materials in order to meet a housing need in a sustainable way, at which the used materials retain their value during and after the use phase’’ (Green Deal Circulaire Gebouwen, 2016). Copper8 and Alba Concepts are using the following definition in their research commissioned by municipality of Amsterdam: Circular constructing is ‘’the use of materials that have been reused or can be reused in such a way that these can be detached and be reused again’’ (Copper8 & Alba Concepts, 2017). In the same document they discuss the degree of circularity of a building. They argue that no building can be 100% circular at the moment, because there are no circular alternatives for all the material used in a building. On the other hand, even traditional buildings are circular to a certain extent (Copper8 & Alba Concepts, 2017). The circularity of a building can be assigned to different building levels and layers.
First has to be explained what is meant by building levels. A building can be distinguished in multiple levels. Durmisevic and Brouwer (2002) have written in their article that a building should be described at any level of abstraction. They distinguish four levels in hierarchical order: building, system, component and element (Durmisevic & Brouwer, 2006). In a similar way distinguish Copper8 and Alba Concepts (2017) five different levels: building, systems, elements, products, and materials (Copper8 & Alba Concepts, 2017). The concept of both is the same, only an extra level is added (material). A graphical representation of a combination of these methods can be found in figure X. A practical example in line with this figure can be: a building consist of a skin (system) and the skin consists of outside walls, windows, doors, etc. (components). A window consists of glass and a window frame (elements), and a window frame consists of wood (materials). The hierarchical order in this example is very clear. In some cases the product is equal to the material, e.g. in the case of glass of a window.
Both Durmisevic & Brouwer (2002) and Copper8 & Alba Concepts (2017) talk about systems. According to the model of Brand (1994) consists a building of six systems, also called the ‘six layers of change’. Layers is equivalent to systems. Many circular initiatives make use of this decomposition (Copper8 & Alba Concepts, 2017; Madaster, 2018; Green Deal Circulaire Gebouwen, 2016). The six layers are:
• Site
• Structure
• Skin
• Services
• Space plan
• Stuff
(Brand, 1994).
This layout is based on the lifespan of different building components. Every layer is called a system, the impact of every system is different due to the amount of raw materials and its lifespan. A shorter lifespan emphasizes the importance of demountability. Circularity has different implications for each system. For example, the owner can be responsible for the structure of the building and the user for the interior design (stuff) (Copper8 & Alba Concepts, 2017; Green Deal Circulaire Gebouwen, 2016). The site is in principle always reusable and the stuff is not part of the actual building, therefore this study will focus on structure, skin, services and space plan.
There are three types of lifespan that can be distinguished: functional lifespan, economical lifespan and technical lifespan. The definition of the three types can be described as follow (Pijl, 2017):
– Functional lifespan: This is the period between completion of a building and the moment it does not meet the desired requirements anymore.
– Economical lifespan: This is the period between completion of a building and the moment another alternative with lower or at least the same exploitation costs exists.
– Technical lifespan: This is the period between completion of a building and the moment it cannot achieve the technical mandatory requirements anymore.
The functional or economical lifespan ends most of the time before the technical lifespan, resulting in vacant buildings or demolishing of buildings that are technical alright. These buildings have to be transformed to get a new function again, but demolishing and developing something new is often cheaper (Debacker & Manshoven, 2016). This brings us to the lifecycle of a building, Debacker and Manshoven (2016) distinguish 4 main building phases:
1. Design: The design of the building is made, including specification of financing and planning.
2. Build: The building gets realized according to specifications, timely and in budget.
3. Use & Operate: The building is taken in to use by one or more occupants as long as it meets the requirements of the occupants.
4. Repurpose & Demolition: The building or building components are getting a new purpose, if this is not possible the building will be demolished.
These 4 building phases appear to be linear, but there are multiple iterative links and loops possible between these phases, especially focusing on repurposing of buildings and building components. By creating a new purpose for every building or building component, the building lifecycle can become circular (Debacker & Manshoven, 2016).
The definition of a circular building and the decomposition and lifespan of a building is clarified in this section. Copper8 & Alba Concepts (2017) argued that no building is 100% circular at this moment. On the other hand are even traditional buildings circular to a certain extent. Next section will be about circularity indexes to determine how circular a building is.
2.6 Circularity index
How can we measure the degree of circularity? This is the central question in this section. First the Material Circularity Indicator developed by the Ellen MacArthur Foundation will be discussed. Thereafter the discussion will zoom in on how to measure the degree of circularity of a building. The Material Circular Indicator (MCI) is a determination method developed by the Ellen MacArthur Foundation and determines the degree of circularity of products and materials. Four aspects are essential to calculate the MCI. First, the mass of virgin raw materials: What is the amount of virgin and recycled materials and what is the amount of reused components? Second, the mass of unrecoverable waste: What can be reused of recycled and what becomes landfill? The goal is to eliminate all waste. Third, utility during use phase: What is the lifespan of the product compared to an average product of similar type? Important are for example durability, repair/upgrade and a sharing economy. And last, the efficiency of recycling: How easy is the recycling process of the product? The exact formulas for the calculation of the MCI are left out of consideration here, but will give a value between 0 and 1. A fully linear product will get a value 0 and a fully circular product a value 1 (Ellen MacArthur Foundation, 2015).
A building consists of multiple materials and every material has its own MCI. The average MCI determines the circularity of a building, also called a Mixed Material Circularity Indicator. Calculating the average MCI can be done in multiple ways, the Ellen MacArthur Foundation uses the mass of the used material. This method can only be applied when the parts are demountable (Paauw & Drijfhout, 2018).
The circularity index developed by Copper8 and Alba Concepts (2017) is based on the ‘Circularity Indicators’ framework of the Ellen MacArthur Foundation and the six-layer model of Brand. The model consists of different levels: Product Circularity Index (PCI), Element Circularity Index (ECI), System Circularity Index (SCI) and Building Circularity Index (GCI). Taken into account is the origin of materials, waste scenarios, demountability, lifespan and specific weight of materials. The PCI is based on the Material Index (MI) and the Demountability Index (LI). The ECI is based on the PCI and the ratio of the weight of the different products. The SCI and GCI are based on the ECI and the ratio of specific weight. Systems with a high specific weight, like the structure of the building, influence the circularity of the building the most. Figure X shows a schematic representation of these indexes, including the calculations.
So, a circularity index can determine how circular a product or building is, but both indexes do not include a value aspect. The circularity index developed by Copper8 and Alba Concepts (2017) is specified on buildings and the index can be applied for different building levels based on the model of Brand. The literature is not clear at which building level the most value is added with circularity. Section 2.7 will dive into the challenges for a circular economy.
2.7 Challenges for Circular Economy
The concept of a circular economy sounds really positive, but why do we still have a linear economy then? This section will zoom in on the barriers to a transition from a linear to a circular economy. Ritzén and Sandström (2017) identified in their article six main barriers for moving towards a circular economy. These barriers are in line with their literature research. Kok, Wurpel and Ten Wolde (2013) speak about ‘obstacles’ before we can create a circular economy. They also suggest some steps (actions) to overcome the obstacles. The barriers identified by Ritzén and Sandström are partly in line with the obstacles and are summed up in the next table (Ritzén & Sandström, 2017) (Kok, Wurpel, & Ten Wolde, 2013).
Financial
– Measuring financial benefits of circular economy
– Financial profitability
– Major up-front investment costs
– Environmental costs (externalities) are not taken into account
– Shareholders with short-term agenda dominate corporate governance
– Recycled materials are often still more expensive than virgin
– Higher costs for management and planning
(Infra)structural
– Missing exchange of information
– Unclear responsibility distribution
– Infrastructure/ supply chain management
– Limited application of new business models
– Confidentiality and trust issues hamper exchange of information
– Exchange of materials is limited by capacity of reverse logistics
Institutional
– Unlevel playing field created by current institutions
– Financial governmental incentives support the linear economy
– Circularity is not effectively integrated in innovation policies
– Competition legislation inhibits collaboration between companies
– Recycling policies are ineffective to obtain high quality recycling
– Governance issues concerning responsibilities, liabilities and ownership
Societal
– Perception of sustainability
– Risk Aversion
– Lack of awareness and sense of urgency, also in businesses
– GDP does not show the real progress or decline of our society
– Resistance from powerful stakeholders with large interests in status quo
Technological
– Product design
– Integration into production processes
– Limited attention for end-of-life phase in current product designs
– Limited availability and quality of recycling material
– New challenges to separate the bio- from the techno cycle
– Linear technologies are deeply rooted
These obstacles and barriers show that the circular economy still has a long way to go. Material passports can help to overcome some of these challenges, it will for example be the answer to the missing exchange information about the building. It will probably also stimulate in helping overcome other barriers, the next chapter will zoom in further on material passports.
2.8 Circular Economy conclusion
The linear model of production and consumption, including a take-make-dispose pattern, dominates our current global economy since the mid-20th century but cannot be sustained in the future. Our resources are shrinking and the externalities are increasing. A new type of economy is needed. The circular economy can be described as ‘an economy that is restorative and regenerative by design and aims to keep products, components, and materials at their highest utility and value at all times’ (Ellen MacArthur Foundation, 2015). It is based on three principles:
– Principle 1: Finite resources should be controlled and renewable resources should be balanced in order to maintain and improve natural capital.
– Principle 2: Let products, components, and materials always circulate in both biological and technical cycle at their highest use possible in order to optimize resource yields.
– Principle 3: Negative side effects or consequences should be designed out (Ellen MacArthur Foundation, 2015)
The negative externalities as a result of the linear economy tend to aggravate due to a changing world population. Not only is the world population growing by roughly 83 million people annually, also the middle class is growing exponential. This positive economic evolution will contradictory increase the negative externalities. One of the sectors with the highest priority is the building sector. The built environment is one of the largest and most resource intensive value chains in our economy (Ellen MacArthur Foundation, 2015). It is also the biggest contributor to climate change; buildings produce 30-40% of total global greenhouse gas emissions. The waste produced in this sector accounts for 30-40% of the total waste production (Adams, Osmani, Thornback, & Thorpe, 2017; Vos, Wullink, de Lange, Van Acoleyen, van Staveren, & von Meijenfeldt, 2016; Sante, 2017; Circle Economy, van Odijk, van Bovene, 2014). Lehmann (2011) even suggests that the construction sector uses more materials, produces more waste and contributes less to recycling than every other sector in our economy.
Current scientific literature and researches tend to focus on circularity at city level (macro-level) and material level (micro-level), but only little research is at building-level (meso-level). Research at this fundamental level is critical for understanding and applying the circular economy in the built environment. Green Deal Circulaire Gebouwen (GDCG) is a collaboration between the Dutch government, companies and institutions with the aim to translate the circular economy principles and ideas into buildings. According to them is a circular building: ‘’A building that is designed, developed, managed and used according to the circular economy system, where a decrease in the use of raw materials and maximizing reuse a central aspect of the building is. The aim is to use as few new raw materials as possible and where products, raw materials and systems are used, keeping them as long as possible (on a high value level) in the construction chain’’ (Green Deal Circulaire Gebouwen, 2015, p. 1). Copper8 & AlbaConcepts (2017) argue that no building can be 100% circular at the moment, because there are no circular alternatives for all the material used in a building. On the other hand, even traditional buildings are circular to a certain extent (Copper8 & Alba Concepts, 2017). The circularity of a building can be assigned to different building levels and layers. A building can be decomposed in systems, elements, components and materials. Systems and elements can be reused, components can be remanufactured and materials can be recycled. In general can six systems be distinguished based on its lifespan: site, structure, skin, services, space plan, stuff (Brand, 1994). But how can the degree of circularity be measured? Therefore a circularity index can be used. The existing circularity indexes show which factors are important for the circularity of a building, but they do not include any value aspect.
An elaborated answer is given to the first sub-question of this research: ‘’What is a circular economy and what is the influence on the built environment?’’ The concept of a circular economy in the built environment is clear now and it sounds all really positive, but why do we still have a linear economy then? There are some barriers and obstacles for moving towards a circular economy. The main barriers are financial, (infra)structural, institutional, societal, and technological. Material passports can help to overcome some of these challenges, this will be discussed in chapter 3
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