Keywords

1 Introduction

In the context of the escalating global imperative to address climate change and environmental sustainability, decarbonization by 2050 constitutes a central focus within the European Union’s overarching strategies for the upcoming years [1]. At the heart of this vision lies the Circular Economy (CE) strategy, which seeks to maximize recycling and renovation rates to reduce dependence on primary resources. This initiative aligns with the objectives of the European Green Deal and the 2030 Agenda for Sustainable Development.

The construction sector stands as one of the largest consumers of energy and is accountable for 40% of global CO2 emissions [2], along with being responsible for 60% of the global consumption of raw materials [3]. Despite the significant impact of this sector on both energy consumption and raw material use, there is a pressing need to accelerate building renovations. Current rates of energy renovations in the European Union (EU) hover around a mere 0.2% on average. In contrast, the EU has set ambitious targets to double these figures by 2030, also fostering deep renovations [4].

In this context, the present study focuses on exploring and analyzing the relevance and potentials of Material and Building Passports (MPs and BPs) in the transition towards a CE. These passports not only provide an effective tool to raise awareness about building performance among all stakeholders involved but also enable the digital storage of critical information, facilitate stakeholder consultation prior to any renovation action, and contribute to efficient energy management and recording of building operations. Thus, the novelty of this paper lies in the examination of the contribution of these passports at each stage of the building life cycle.

This study is situated within a growing body of literature that underscores the importance of MPs and BPs in the transition towards the CE and builds upon systematic reviews and analyses of the digital tools’ applications, which are being recognized as key elements in this process.

2 Methodology

The research aims to underscore the significance of MPs and BPs in promoting circularity in buildings across various life cycle stages. To achieve this objective, the study conducts a comprehensive state-of-the-art analysis on these concepts, elucidating their distinctions and applications in supporting sustainable and circular practices in the building sector. The analysis encompasses the origins and definitions of MPs and BPs, and historical developments. The primary focus of the paper is on examining the roles and opportunities presented by passports in the building sector. The research delves into the capabilities of passports across four key life cycle stages of buildings: 1) Design stage, 2) Construction stage, 3) Operation and maintenance, and 4) End-of-Life (EoL) management. This examination explores how passports can facilitate closed loops and circular feedback systems, thereby enhancing the efficiency of management practices and fostering connections among stakeholders. The discussion section sheds light on the multidimensional barriers that impede the widespread adoption of passports and identifies potential opportunities to address them. By presenting a nuanced discussion on the challenges, opportunities, and future prospects, the research contributes to a more thorough understanding of the role of passports in advancing circularity in the building sector.

3 State-of-the-Art of Material and Building Passports

Building Passports have been present in Europe for several decades, with their roots tracing back almost 30 years to the mid-90s. The first BP initiatives emerged in Germany [5] and Denmark, where the “Det digitale energimærke” was introduced [6]. Despite the prolonged existence of these initiatives, there is no universally agreed definition of the tool. Different regions in Europe have adopted varying approaches, encompassing aspects from energy performance to technological data [5]. However, what appears to be widely accepted is that BPs serve as tools providing relevant information about buildings to diverse stakeholders within the building sector. The specifics of content and format, nevertheless, vary across different initiatives.

With the surge in renovation activities, a new iteration of these passports has emerged, known as the “Building Renovation Passport” (BRP) [5]. This version is specifically tailored for existing buildings undergoing staged renovation. Although there is no single model for this tool, there is a consensus that it should consist of two key parts: a digital building logbook (DBL) that compiles all information about the building and a renovation roadmap that guides the owner through the necessary steps to transform buildings into zero-emission ones by 2050 [7].

Unlike the BP, which was primarily associated with national or regional initiatives, the BRP has been included into European legislation due to its potential to catalyze building renovation. In 2021, the first version of the proposal for the recast of the Energy Performance of Buildings Directive (EPBD) officially agreed on a definition—this definition was slightly modified in the 2023 amended version of the Directive [7]. Additionally, an agreed common scheme will be developed soon to be applicable to all EU Member States (MS).

Simultaneously, there have been recent developments in the creation of another building-related passport system known as the Material Passport (MP). MPs are designed to collect and store data on the materials constituting buildings, offering valuable insights for assessing the circularity of buildings and facilitating decision-making regarding recovery, recycling, and reuse [8]. According to van Capelleveen [9], the earliest reference to this passport concept dates back to O’Shea [10], where it was initially referred to as the Product Passport (PP). Presently, this concept is being incorporated into European legislation under the designation of Digital Product Passport (DPP), with its definition and content outlined in the proposal for a new Ecodesign for Sustainable Products Regulation (ESPR). The DPP doesn’t exclusively concentrate on building materials but encompasses them within its broader scope.

According to Buchholz and Lützkendorf [11], MP can function independently or be integrated into a multifunctional system, such as the mentioned DBLs. In alignment with this concept, the European Commission (EC) is currently in the process of developing the DBL to serve as comprehensive repositories, encompassing not only data but also documents and certificates related to buildings, such as Energy Performance Certificates (EPCs), BRPs, and MPs-DPPs [7]. However, connecting all these records into a single repository or gateway is highly complex due to factors such as format compatibility and the lack of interoperability of some data sources [12].

Observations reveal that, despite numerous advancements, a common definition for the diverse tools in question has yet to be established. Regarding the BRP, the 2023 proposal for the EPBD recast stipulates that by the end of 2024, MSs shall introduce a scheme. To achieve this, a common European framework is expected to be adopted by the end of 2023.

Turning to the European DBL, which emerged as an independent tool in the Renovation Wave, several advancements have already been made, both by the EC and independent studies or research projects [13]. However, a universally agreed-upon model is still absent, and new models are emerging based on new functionalities proposed for the DBL [14, 15]. Despite the near-term implementation appearing unlikely due to numerous existing barriers that require resolution, the 2023 proposal for the EPBD recast states that by the end of 2024, the EC will establish a common template for the tool.

Regarding the MP, it is evident that various alternative terminologies such as Product Passport, Resource Passport, Recycling Passport, Cradle-to-cradle Passport, etc., are used to refer to this phenomenon. This diversity in nomenclature underscores a lack of homogeneity and definition thus far. We suggest that these passports can best be defined as a digital interface composing a certified identity of a single identifiable product by accessing the set of life cycle registrations linked to this object to yield insight into the sustainability and circularity characteristics [9].

Within the ongoing process of establishing criteria for defining these tools, it becomes imperative to clarify their potential and role in driving the transition towards a CE in the context of building construction.

4 The Role and Potential of Material and Building Passports in Promoting Circularity in Existing and New Buildings

MPs serve as digital interfaces, encapsulating the verified identity of singular products. This identity is established by accessing a comprehensive set of life cycle registrations associated with the object. The primary purpose is to provide insights into the sustainability and circularity characteristics, circular value estimation, and circular opportunities for both the product and its underlying components and materials. MPs play a pivotal role in advancing circularity across various scales, ranging from individual materials through buildings to entire urban clusters. At the building scale, they function as crucial tools supporting circular practices throughout the building’s life cycle—from design to construction to operation until EoL management.

BPs, on the other hand, are associated with a specific building, accompanying it throughout its lifespan. They contain data enabling its comprehensive description and characterization, while also documenting any alterations or interventions made to it. Moreover, BPs serve as a point of access to all external documents related to the building.

The following sections analyze the potential of MPs and BPs in all the stages of a building’s life cycle.

4.1 Design Phase: New Buildings and Renovation

Despite their utility across all stages of a building’s life cycle, the optimal utilization of MPs involves their meticulous preparation and integration during the design phase. This strategic incorporation enables the creation of specific scenarios, empowering informed decision-making regarding data management and governance throughout the entire life cycle of the building.

Utilizing MPs during the design phase ensures that all materials and components are purposely designed for easy reuse, recovery, and repair in subsequent life cycle stages. This approach conceptualizes buildings as material banks, optimizing design while minimizing the use of primary resources and contributing to a waste-free CE. The novelty of MPs lies in their ability to determine embedded materials, thereby aiding in design optimization. MPs also contain extensive information, including physical, chemical, and biological characteristics, material health data, transportation details, and additional information for effective evaluation and certification [16]. Furthermore, MPs incorporate material cost information, facilitating overall cost calculation from the design stage. This supports economic decision-making, including assessing the economic viability of a building and other economic aspects over its entire life cycle. This comprehensive approach helps determine the necessary monetary input to improve the sustainable and circular performance of the building model [17].

In addition to containing and linking all the information that characterizes the materials and products constituting buildings, compiled through MPs, BPs, and DBLs allow the characterization of many other aspects. The design phase emerges as the opportune time for developing BPs, BRPs, and DBLs, generating valuable information that proves highly useful in subsequent phases of the building’s life cycle.

In the specific case of the design for a renovation, the BRP is of great relevance. As mentioned before, BRPs consist of a DBL, which doubles as an independent data repository and a renovation roadmap. The DBL empowers professionals with essential building information collected during or prior to the design stage, facilitating the design for renovation. Concurrently, the renovation roadmap provides guidance to property owners throughout the staged renovation process.

A significant nexus arises between the DBL and the MP, advocating for the inclusion of a material inventory in the DBL, functioning akin to a MP.

Furthermore, the design phase generates substantial information about materials and products slated for use during the building’s construction phase. In this context, BPs, especially DBLs, serve as ideal repositories for storing such information. The stored data proves instrumental during the building use, maintenance, future interventions, and eventual deconstruction.

To harness the full potential of passports from the design stage, integration with other technologies, particularly Building Information Modeling (BIM), is common. The incorporation of MPs and BPs into BIM models presents a promising avenue for enhancing sustainability and circularity in the construction sector. The generation of BIM-based MPs and BPs facilitates real-time updates, enabling their use for optimization in early design stages, and fostering increased awareness of recyclability and reusability in construction [17]. Leveraging BIM’s capabilities enables stakeholders to make more informed decisions aligned with the principles of the CE.

4.2 Construction Stage

Within construction processes, a considerable volume of supplementary information is generated, distinct from the design stage. This information originates from suppliers and subcontractors in diverse forms and levels of detail. Apart from traditional plans and information about materials and products, there is an emerging trend to incorporate laser scans of the building, proving beneficial for the creation of passports at both the building and element levels [18, 19]. BPs and DBLs function as optimal repositories for systematically storing this data, ensuring that maintenance operations and subsequent interventions are well-informed and aligned with the building’s history.

An especially noteworthy context for the implementation of MPs and BPs is found in the realm of industrialized construction [20], wherein the manufacturing process occurs off-site while the assembly takes place on-site. This assembly process generates a substantial amount of data [21], which is crucial in anticipation of the eventual disassembly [22, 23] and recycling of building components.

Beyond their role in generating and storing information, BPs and MPs also contribute to on-site quality control by documenting details regarding the quality standards and specifications of materials. This documentation aids in the construction of structures that are durable and resilient. In the same way, these data also assist in assessing compliance with environmental regulations and standards.

Additionally, waste generation during the construction phase may arise from design faults, on-site errors, workflow confusion, unanticipated plant breakdowns, and rehabilitation [24,25,26]. Intelligent waste recycling management play a crucial role in enhancing supply chain construction plans.

4.3 Operation and Use of Buildings

During the operation and use stage, MPs and BPs present significant potentials related to predictive maintenance, management, and optimization of building performance.

In the context of building maintenance, MPs offer a comprehensive overview of the building components, encompassing details on materials’ durability, expected lifespan, and recommended maintenance practices. This information is invaluable for promptly identifying and resolving issues. Additionally, it opens up the possibility for BPs and the DBLs to function as user-friendly maintenance manuals [27].

Passports also play a vital role in improving the energy efficiency of buildings. They not only furnish details on the thermal properties of components but also serve as repositories for data gathered through smart monitoring. These data, when integrated with Artificial Intelligence (AI), enable the automation of the building systems and the optimization of their energy consumption while improving thermal comfort [19].

Finally, MPs, BPs, and DBLs serve to provide and circulate information among stakeholders involved in each stage of the chain. This ensures proper management to support decision-making regarding acquisition, maintenance, and user requirements.

However, despite the effectiveness of BP and MPs as data repositories and “gateways” during this stage, data acquisition remains a primary challenge. As stated by Gómez-Gil et al. [13], a large amount of data is generated throughout a building’s lifespan, yet there is a general lack of strategies to manage and correlate this data. In fact, currently, the actual data used for facility management is handled on a day-to-day basis with no general data storage or accessible memory repositories.

4.4 End-of-Life, Recycle, Reuse and Construction, and Demolition Waste Management

MPs and BPs play a crucial role in fostering circularity during the EoL stage of a building and managing the waste produced during its demolition or deconstruction. Comprehensive knowledge of all the materials that constitute a building, along with their properties and quantities, as well as all the building’s components, provides technicians with the ability to systematically organize the demolition or deconstruction procedure. This foresight allows for the meticulous predetermination of materials and components that can be reused, recycled, or recovered, even from the design stage.

To be more specific, MPs and BPs in conjunction with new technologies, such as BIM, can be capitalized on verifying the optimum demolition or deconstruction procedure along with the most efficient construction and demolition waste (CDW) management to be followed [28]. Regarding the materials and components resulting from a demolition process, a cost-benefit analysis can demonstrate the most suitable management activity (e.g., upcycling, reuse, recycle) for each specific one. Making use also of other advanced technologies, the optimum transportation path of the produced waste can be also defined to further improve the circularity and sustainability efforts [29].

Focusing more on MPs, validated models promoting effective CDW management can be detected in the international literature [30]. In a referenced study, researchers integrated sustainability assessment indicators in MPs. Another project developed a BIM-based MP to evaluate both the recyclability of a building’s materials and their environmental footprint after the building’s demolition [31]. However, the researchers acknowledge the need for additional properties to be considered in their MP for a more holistic approach, such as the reusability of materials.

5 Discussion and Conclusions

MPs and BPs serve as valuable tools throughout all stages of a building’s life cycle, enabling the collection, storage, and sharing of substantial amounts of building-related data, including general information, architectural survey/geometry, construction details, material inventory, predictive maintenance plans, features of building systems, accessibility conditions, what-if analysis, performance optimization, real-time energy use measurement, behavioral insights, water resources assessment, health and comfort evaluation, and life cycle optimization.

On the one hand, the evolution of the BP has lied the foundation for standardized assessment of energy performance in buildings. On the other hand, the MP has not been reached the same level of granularity. Despite notable individual examples, such as the BAMB2020 - Building As Material Banks initiative, there lacks a comprehensive international standard for indexing the circularity of building materials. Thus, as these tools are taking shape, it was crucial to emphasize their potential to promote circularity throughout the entire life cycle of buildings.

Despite the acknowledged importance of MPs and BPs, their widespread applications are hindered by various factors. Challenges include the absence of legislations and standards that support their use, unclear guidelines on their structure and management, and issues related to governance and ownership, including the aspect of data ownership and privacy protection.

Another barrier to the implementation of these tools is the scarcity of data, especially regarding materials from existing buildings, and the lack of shared information about materials, particularly on LCA and EoL [32, 33]. While there are numerous common databases that provide valuable information to feed BPs, such as national cadasters, land registries, or EPC registries, in some countries there are different sources at smaller levels, which makes it hard to create a complete picture of the situation in Europe. Furthermore, some of those sources are either not interoperable or do not collect sufficient data, which is why new data sources have been identified in the literature. They include new technologies for data acquisition, such as 3D scanning or smart monitoring, and upcoming EU tools, such as the Level(s) framework or the Smart Readiness Indicator, which are called to generate valuable data [12].

To implement these passports and distribute responsibilities for them, including their maintenance and the management of financial and production chains, a high level of collaboration among stakeholders is required. Financial barriers further compound the issue, as both capital and operational costs are high. Despite the potential long-term benefits, value chain stakeholders often perceive the initial costs as unjustified, particularly in the context of profitable businesses. Lastly, the overall adoption of digital technologies and tools, including MPs and BPs, is impeded by a lack of knowledge about their applications and capacities. Achieving a widespread understanding among actors is crucial for utilizing these tools effectively and leveraging their potential to support sustainable and circular practices in the built environment.