13. The Role of Digital Building Logbooks for a Circular Built Environment

Several European policy documents, ranging from European legislation to future recommendations, have been established to pave the way for a low carbon, digital, and circular Europe. Despite the emphasis on the ‘energy efficiency first’ principle, there is a clear trend towards the inclusion of embodied greenhouse gases and whole life carbon in order to meet climate targets and decouple growth from resource use (European Commission 2019). In this context, the review of the Ecodesign framework, foreseen by 2025, will establish mandatory DPPs to improve the traceability of products along the value chain (Directorate-General for Environment European Commission 2022), including construction-related products. At the building scale, DBLs are specifically referred to in the Energy Performance in Buildings Directive (EPBD) recast proposal (European Commission 2021a), as tools to promote circular economy principles throughout the life cycle of buildings. The EPBD recast proposal (European Commission 2021a) also outlines the concept of a building renovation passport as a customised action plan for a specific building to help it achieve a higher level of energy efficiency.

In 2020, the European Commission commissioned a study on the development of a European Union framework for the DBLs (Dourlens-Quaranta et al. 2021). In several European countries, DBLs are already in use or in the process of being introduced (Jansen et al. 2022; Gómez-Gil et al. 2022). Some of these can be identified as a DPP or MP. The differences in scope between these digital tools are still a topic of discussion, as they can be related to the scale of implementation (from material and product to building), life cycle stages coverage, and scope of the contents. All three – DBLs, DPPs and MPs – are intended to be useful throughout the whole life cycle of a product. However, they have different focus: DPPs are created in the moment of production; MPs can be created during design and construction or at the end-of-life stage of a product or a building (Honic et al. 2021), but their most essential contribution lies at the beginning and at the end-of-life and next-use stages, enabling reuse and recovery of materials (see Chap. 5 by Honic et al.); and the main focus of DBLs is the use stage, as represented in Fig. 13.1. DBLs might ‘nest’ lower-level passports (such as DPPs or MPs), so that information can be inherited at a higher (building) level from underlying levels (components or materials) (Platform CB’23 2020). Furthermore, DBLs can be seen as ‘living’ logbooks that can be updated, automatically or not, during the life cycle stages, and they can include information related to energy performance, health and comfort, and operational management, while DPPs and MPs tend to be more static.

A block diagram represents the interaction between the main focus layers of product, construction, use, end of life, and next use, a digital product passport, a material passport, and a digital building logbook.

The EU Parliament’s Strategy for a Sustainable Built Environment, aiming to set the legislative priorities for the built environment regarding the implementation of the European Green Deal, refers to the importance of DBLs to increase material efficiency and to reduce the climate impact of the built environment, in particular by promoting circularity principles throughout the life cycle of buildings (European Parliament 2023). DBLs are an ‘important means to achieve a more circular construction sector, as they promote reuse at the material, product, element, and building scale’ (Platform CB’23 2020). In addition, DBLs can promote the principles of durability, adaptability, and circularity principles throughout the life cycle of a building (Hartenberger et al. 2021). As with DBLs, information on the installed construction elements, components and materials, their lifespan, and the possibilities for dismantling, reuse, and recycling can be systematically collected, organised, and updated. In this way, DBLs can improve the overall transparency, trust, and cooperation between different stakeholders and support sustainable decision-making when it comes to modifying actions during the life cycle of a building, ultimately preserving the value of the materials. DBLs can help maintain the value of the building throughout its life cycle and contribute to smarter use of materials and products (narrowing the loop), extending the life of buildings and components (slowing the loop) and ensuring beneficial end of life (closing the loop).

This section presents examples of DBLs developed in five geographical contexts with different local drivers and normative frameworks: France (CLÉA), the UK (Residential Logbook Association/Chimni), Germany (CAPSA), Belgium (De Woningpas), and the Netherlands (CIRDAX). These DBLs were chosen to showcase the wide variety of legal and market backgrounds, level of maturity, functionalities, and target audiences. The DBLs are analysed in terms of functionalities, data management, data fields, and contribution to circularity strategies.

Ambitions for developing DBLs and increasing the contribution to a circular built environment vary widely depending on the current level of complexity and stakeholders targeted. Most of the current DBLs still have a one-dimensional focus on the use phase and operational energy consumption, with little coverage of the whole cycle (Hartenberger et al. 2021). DBLs such as Woningpas are aiming to integrate external data from smart meters to monitor real performance, and CAPSA has already done so. Some of the DBLs presented already provide users with automated renovation advice (Woningpas) or detailed decarbonisation roadmaps (CAPSA), which can support the renovation of the building stock, investment decision-making, and access to EU funding, green financing, and insurance products.

According to the European Commission, the automatic input of data from a BIM model (see Chap. 1 by Koutamanis) is considered important for the majority of stakeholders (Dourlens-Quaranta et al. 2021), as it would contribute to speeding up the processes and reducing costs – two major barriers to the implementation of DBLs (Dourlens-Quaranta et al. 2021). This is not yet common practice, as the analysis of cases demonstrated, with only CIRDAX offering that possibility, and Chimni actively working on its integration with the DBL.

Collaboration is an essential strategy in the transition towards a circular built environment (Çetin et al. 2021), which will require integrating needs and expectations of multiple stakeholders at multiple scales. Understanding the building as a part of a larger complex system shaped by social, economic, and environmental forces is important for identifying flows of material products and waste across different scales. DBLs contribute to a better overview of the existing building stock and can enhance collective approaches that significantly reduce impacts at the neighbourhood and urban levels. DBLs, together with GIS technologies (see Chap. 2 by Tsui et al.), can support community-driven decarbonisation and the decentralisation of water, energy, and waste flows and simultaneously establish urban mining networks with information on the location and availability of materials.

To improve the contribution towards a circular built environment, the next generation of DBLs needs to go beyond energy and support sustainable flows throughout the entire life cycle of the building and beyond. In the study of the European Commission, participating stakeholders identify the building material inventory as one of the most important features (Dourlens-Quaranta et al. 2021). However, the analysis of the practical cases in this chapter shows that DBLs integrating this feature are still the exception and not the common practice. Requiring a bill of materials could increase the completeness and accuracy of the DBLs (Platform CB’23 2020) in the early stages and, later on, facilitate the traceability of embodied carbon and life cycle costing (Hartenberger et al. 2021). It also would offer an opportunity to integrate DBLs with current policy frameworks, such as LEVEL(s), by providing the necessary information to assess resource efficiency and material life cycles (European Commission 2021b), as soon required by the EPBD (European Commission 2021a).

To ensure that DBLs are effectively useful tools, a more systematic and aligned approach to data collection, storage, and exchange is needed. Passports should allow comparison and interchange of information, and ‘it is important that everyone uses the same technical terms and uses the same definitions’ (Platform CB’23 2020). The five practical cases analysed show that the same functionalities may mean different things in the different DBLs. This was clear in the data fields related to general cadastre information and building characterisations, for instance, and in the integration of maintenance advice or environmental product declarations (EPDs). Future developments need to establish protocols and tools to ensure interoperability and compatibility of information so that DBLs are effective tools for information sharing and not obstacles to access. A harmonised framework of minimum requirements and protocols for DBLs is essential to ensure that accurate and correct data is available while still allowing for a diverse range of DBLs to meet different market needs and local drivers. Standardisation of minimum requirements goes hand in hand with the financing of the development of DBLs (Dourlens-Quaranta et al. 2021): certain mandatory aspects can be developed by the public sector (such as Woningpas), ensuring transparency and harmonisation, while more advanced features can be developed with commercial purposes, targeting stakeholders’ specific needs (such as CIRDAX). The highest value for the end-users will be achieved when both approaches can be combined.

User-friendliness is a key factor determining the success of DBLs. Greater market uptake depends on the extent to which governments impose obligations (Platform CB’23 2020), but also on a better understanding of users’ needs, attitudes, and personal motivations (Gonçalves et al. 2021), as there is no ‘one-size-fits-all’ solution for DBLs. Despite the overarching benefits of implementing DBLs identified in the findings, not all levels of information are relevant to all stakeholders. Therefore, DBLs, despite their role as an information hub, need to allow for different levels of granularity and user roles to avoid overburdening stakeholders with additional work and costs for data storage and management (Hartenberger et al. 2021). A key issue for the successful development and large-scale application of DBLs will depend on the business model. While the overarching objectives of DBLs are in line with the EU and national ambitions, it does not seem to be the case here as well; there is no one-size-fits-all solution for DBLs. Some will be based on a B2B model, B2C model, or fully supported by governments. For the B2B and B2C models, it will be key to define clear unique selling propositions that generate value for the customer.

DBLs have the potential to contribute to three main circularity goals: (1) measuring achieved circularity; (2) management and maintenance in the use phase; and (3) facilitating future reuse and value retention (Platform CB’23 2020). Despite the different levels of complexity and detail, all the five DBLs presented in this chapter contribute to the second goal, facilitating the maintenance of the existing building stock; CAPSA and CIRDAX include some functionalities that contribute to the first goal, namely the material inventory and calculation of embodied carbon, but only CIRDAX actively aims at future circularity, value retention, and circular potential. Future developments should integrate renovation advice with MPs (see Chap. 5) and reuse marketplaces with blockchain technology (see Chap. 13). This would allow to balance achievements on operational and embodied carbon and make the most of the resources already existing in the building or its surroundings to avoid disposal and loss of value and enable multiple life cycles.

The development of DBLs presents challenges ahead, but the practical cases of DBLs already implemented demonstrate the potential of DBLs to enable a circular economy in the four strategies proposed by Çetin et al. (2021). They facilitate the upgrade and improvement of energy efficiency in buildings in the use phase (narrowing resource loops); contribute to extending buildings’ lifetime through maintenance and repair, and enabling smart reuse of space (slowing resource loops); enable tracking, tracing, and bringing material resources back into the economic cycle in the next-use phase (closing resource loops); and contribute to a net positive impact when including indicators on biodiversity, surplus resources, and environmental quality (regenerating resource loops).