Marlies Reher
The construction sector accounts for a massive consumption of non-renewable resources to produce building materials like concrete, steel, and glass. Hence, the recycling of building materials is of utmost importance to promote sustainability. However, the current recycling rate of construction and demolition waste is only 20-30%. One solution to this problem is the introduction of a materials passport for buildings.
The role of the construction sector in sustainable development
Currently, the construction sector accounts for 50% of energy use, 40% of all greenhouse gas emissions, 50% of all raw material extractions, 33% of all water use, and 36% of solid waste in the EU, which is more than any other industry sector (European Commission, 2019). In view of a growing world population estimated to be 9 billion people in 2050 (UNEP, 2011), the demand for building materials will increase further. The required resources (e.g., ores, gravel, sand, limestone, among others) for building materials are finite and non-renewable, so recycling and reuse of building materials and demolition waste is necessary to satisfy the demand. Furthermore, recycling and reuse offer the advantages of being independent of resource imports of other countries and volatile resource prices (Heisel & Rau-Oberhuber, 2020).
To promote recycling and reuse, the European Commission developed the “Circular Economy Action Plan” in 2015 with 54 actions and four legislative proposals regarding waste that are aimed to be fulfilled by 2030. Recycling and reuse are key elements in the concept of “circular economy”. The Ellen MacArthur Foundation defines circular economy 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, distinguishing between technical and biological cycles” (Ellen MacArthur Foundation, 2015). The concept stands in contrast to the linear concept of “take-make-waste”, which has been practiced since the industrial revolution. Within the concept of circular economy, the concept of Urban Mining sees buildings and infrastructure as material banks. To enable Urban Mining, three important design and construction principles need to be followed according to Heisel and Rau-Oberhuber: 1. Design for disassembly, 2. Design for adaptability, and 3. Use of high-quality, non-toxic, and circular components, elements, and materials (Heisel & Rau-Oberhuber, 2020).
However, the recycling rate of construction and demolition waste is currently only 20-30% (WEF, 2016). Reasons for the low recycling rate are barriers of different types. Apart from technological barriers like inefficient recycling due to missing information on materials composition, there are moreover economic, political, sociological, environmental, and organisational barriers (Charef & Emmitt, 2021). For example, costs for recycling and missing policies to enforce recycling are hindering the increase of the recycling rate. Furthermore, in newly constructed buildings, the amount of recycled material is still very small due to lacking trust in the quality of recycled materials as well as missing certification. Information on the composition of the buildings is required to use existing buildings as urban mines. Currently, the information about this existing materials stock is missing, inaccessible, or incomplete. (Munaro & Tavares, 2021)
The Materials Passport to promote Urban Mining and Circular Economy
One solution to promote Urban Mining and Circular Economy is the introduction of a Materials Passport for each building. A Materials Passport is more than just a simple list of materials used in the building, but gives information on which materials in what quantities and qualities become available for reuse and recycling where and at what time in the future (Heisel & Rau-Oberhuber, 2020; Luscuere, 2017). It can be understood as a digital dataset that tracks the circular potential of a building and fulfills a purpose at each stage of the life cycle of a building. For example, during planning, a Materials Passport can serve as a decision-making tool to construct in a more sustainable manner. At the building’s end of life, it serves as a manual on how to disassemble and recycle each component. For further information at other stages of the life cycle, see figure 1. Overall, the Materials Passport is an indicator for Circular Economy and sustainability in the construction sector (Munaro & Tavares, 2021).
Figure 1: Information shared across the life cycle of a building to improve material recovery and reuse (Munaro & Tavares, 2021)
Honic et al. as well as Charef & Emmitt suggest generating the Materials Passport based on Building Information Modelling (BIM). A BIM model is created with object-oriented software and contains information for design, fabrication, and construction activities (Honic et al., 2019). This BIM model could then be fed into software or into an add-on for the BIM software that generates the passport. Ideally, the advantage would be the efficient automation of the passport generation. First software packages to create Materials Passports are, e.g. Madaster, BAMB, SundaHus, or BuildingOne.
An example of a building having a Materials Passport is the Urban Mining and Recycling (UMAR) unit in the NEST building on the campus of the Swiss Federal Laboratories for Materials Science and Technology (Empa) in Dübendorf, Switzerland (Heisel & Rau-Oberhuber, 2020).
Why is the Materials Passport not widely implemented yet?
Currently, the concept of Materials Passports is barely implemented due to different reasons. The construction industry tends to be one of the most conservative industries and is poorly digitalised (Charef & Emmitt, 2021; Munaro & Tavares, 2021). Therefore, it is challenging to gather complete and reliable information for the passport. It is hindering that a large number of participants and contract relations are usually involved in construction projects (Munaro & Tavares, 2021). Establishing collaborations and policies is essential, and awareness needs to be raised in society (Honic et al., 2019), see figure 2.
Figure 2: Data- and stakeholder management framework (Honic et al., 2019)
Buildings usually have a long life span during which they can have multiple ownership and occupation profiles (Luscuere, 2017). Different stakeholders have to contribute to the Materials Passport and want to acquire different information from the Materials Passport at different times (Luscuere, 2017). A digital solution needs to be implemented so that all stakeholders can access this information without revealing confidential information of other stakeholders. Currently, there is no central registration of Materials Passports at a central platform (Heisel & Rau-Oberhuber, 2020).
To some stakeholders, the motivation to introduce a Materials Passport is missing because no immediate positive effects are achieved, but rather long-term benefits due to the long life span of buildings (Honic et al., 2019).
A huge problem is also the lack of standardisations that would facilitate an easier generation of the Materials Passports (Honic et al., 2019; Luscuere, 2017). However, the industry is hesitating to introduce the required standardisations because this would confine the creativity of architects and civil engineers (Honic et al., 2019).
Conclusion and outlook to the future
Due to the EU Circular Economy Action Plan, it is not a question of whether the Materials Passport will be implemented in the European Union, but rather of when it will be implemented. Once it is mandatory to provide a Materials Passport for each building, huge amounts of data must be generated and kept up to date whenever something is modified in a building. These huge amounts of data require good data management to facilitate a fast, reliable, efficient, and structured flow of information between stakeholders along the life cycle of a building (Munaro & Tavares, 2021). Therefore, the potential arises to implement technologies like artificial intelligence, machine learning, radio frequency identification, and blockchain technologies to cope efficiently with the huge amount of data (Charef & Emmitt, 2021).
References
Charef, R., & Emmitt, S. (2021). Uses of building information modelling for overcoming barriers to a circular economy. Journal of Cleaner Production, 285, 124854. https://doi.org/10.1016/j.jclepro.2020.124854
Ellen MacArthur Foundation. (2015). Towards the circular economy—Economic and business rationale for an accelerated transition. Ellen MacArthur Foundation.
European Commission. (2019). Taking action on the total impact of the construction sector. Publications Office. https://data.europa.eu/doi/10.2779/458570
Heisel, F., & Rau-Oberhuber, S. (2020). Calculation and evaluation of circularity indicators for the built environment using the case studies of UMAR and Madaster. Journal of Cleaner Production, 243, 118482. https://doi.org/10.1016/j.jclepro.2019.118482
Honic, M., Kovacic, I., Sibenik, G., & Rechberger, H. (2019). Data- and stakeholder management framework for the implementation of BIM-based Material Passports. Journal of Building Engineering, 23, 341–350. https://doi.org/10.1016/j.jobe.2019.01.017
Luscuere, L. M. (2017). Materials Passports: Optimising value recovery from materials. Proceedings of the Institution of Civil Engineers – Waste and Resource Management, 170(1), 25–28. https://doi.org/10.1680/jwarm.16.00016
Munaro, M. R., & Tavares, S. F. (2021). Materials passport’s review: Challenges and opportunities toward a circular economy building sector. Built Environment Project and Asset Management, 11(4), 767–782. https://doi.org/10.1108/BEPAM-02-2020-0027
UNEP. (2011). Towards a Green Economy: Pathways to Sustainable Development and Poverty Eradication—A Synthesis for Policy Makers. United Nations Environment Programme. www.unep.org/greeneconomy
WEF. (2016). Shaping the Future of Construction: A Breakthrough in Mindset and Technology. World Economic Forum. https://www.weforum.org/reports/shaping-the-future-of-construction-a-breakthrough-in-mindset-and-technology