Concrete is the most used construction material, accounting for 8% of global CO₂ emissions. Various strategies aim to reduce concrete's embodied carbon, such as using supplementary cementitious materials, utilizing cleaner energy, and carbonation. However, a large potential lies in reusing concrete for new buildings in a Circular Economy, thereby closing material loops and avoiding CO₂ emissions.

This study focuses on the reuse of precast concrete elements. We present a digital workflow for assessing reuse by predicting the remaining service life, estimating CO₂ uptake by natural carbonation, and calculating the embodied carbon savings of concrete reuse. Both carbonation rates from EN 16757 and our investigation were applied to a case study building.

While EN 16757 rates suggest that most precast elements have reached the end of their service life, our assessment shows that these elements have a sufficient lifespan for reuse. Plaster and coverings significantly delay carbonation and extend service life. During the first service life following EN 16757, carbonation was 19,2 kg CO₂/m³, whereas our prediction was 5,4 kg CO₂/m³. Moreover, CO₂ uptake during service life, including reuse, was less than 6% of the embodied carbon. The climate benefits of reuse greatly exceeded those of carbonation.

Furthermore, carbonation did not have a decisive influence when applying Cut-Off, Distributed, and End-of-Life allocations for assessing embodied carbon of re-used elements in subsequent life cycles. The digital workflow is useful in quickly assessing lifespan, carbonation, and embodied carbon of concrete. It can be leveraged as a decision-making tool when designing for reuse.

Several assessment methodologies have been proposed to measure the environmental impact of buildings. However, these methodologies require processing data which is often not available or requires a high integration effort. In this paper, we propose an ontology to describe the use and reuse of prefabricated components in buildings. This ontology describes the relation between the physical object, the building component, with the digital object that represents the element in the building information model. We show that this ontology can be used to answer questions like which building components have been reused and which activities were involved in the life cycle of a building. 

Nowadays, the Digital Twin (DT) concept is one of the most talked-about topics in the building sector. Previous research has addressed both the definition of DT concept and the development of applications for specific purposes, such as facility and asset management, built environment performance monitoring etc. However, the specificity of such applications reduces both its replicability and understanding. This results in the spread of confusion when approaching such concepts. For this reason, this study explores how DTs can be effectively used for educational purposes. The methods used include the integration of several systems and tools, highlighting different approaches for data integration and capture. The proposed methodology was tested on a real case study, the U-building on the KTH Campus in Stockholm, which is equipped with a Building Management System (BMS). The building is used as a pilot in master courses to allow students to produce a first attempt of using a DT, by connecting real-time monitored data and digital objects. The results show how efficient data communication helps towards the organization and assimilation of complex concepts. Furthermore, the testing of several approaches proves the replicability and flexibility of the method within different environments and for several uses.

This paper reviews digital tools for supporting the Circular Economy (CE) in the built environment. The study provides a bibliometric analysis and focuses on computer-aided design (CAD), building information modeling (BIM), and computational plugins that can be used by practitioners. While Life Cycle Assessment (LCA) is the primary methodology for evaluating buildings' environmental performance, the study identifies tools beyond LCA, including computational methods and circularity indicators, that can support the evaluation of circular design strategies. Our review highlights limitations in tools’ functionalities, including a lack of representative data for LCA and underdeveloped circularity indicators. The paper calls for further development of these tools in terms of interoperability aspects, integration of more sources of data for LCA and circularity, and possibilities for a comprehensive evaluation of design choices. Computational plugins offer greater flexibility, while BIM-LCA integrations have the potential to replace dedicated LCA software and spreadsheets. Additionally, the study identifies opportunities for novel digital methods, such as algorithms for circular design with various types of reused building elements, and sharing of digital twins and material passports. This research can inform future studies and support architects and engineers in their efforts to create a sustainable built environment.

Due to urbanization and growing density in cities in the past century, metrics were introduced to assess daylight performance such as minimum sunlight hours and the daylight factor. The paper initially explores the shortcomings of early-stage daylight and sunlight evaluation methods. A novel methodology called Sunlight Autonomy (SA) is proposed for evaluating sunlight performance in buildings. The SA is based on the “Exposure to sunlight” criteria in EN 170307 “Daylight in Buildings,” where a computational method is used for the evaluation on a specified day. The SA concept expands the analysis temporally over the entire year, and spatially on building facades, leading to new metrics for a point of evaluation, and spatial metrics for buildings. The SA methodology is analyzed in a case study across four European cities. The SA metrics on facades between February 1st and March 21st, days in EN 17037, led to differences up to 63%. This revealed a significant shortcoming in EN 17037, relevant for Nordic regions. The differences of spatial metrics between March 21st and 50% of the year were within 5%, and up to 33% between February 1st and 75% of the year. The timestep affects the metrics and a window evaluation showed that the error of a 10-minute analysis was within 5% of daily insolation and 5 days for the annual SA. The potential of these metrics for urban planning and the architectural design process is examined. The interaction between SA and EN 17037, as well as other ongoing research developments, is discussed.

Buildings are major contributors to climate change. Reusing buildings and materials in a circular economy is a promising solution, but we need methods and tools to support it. Therefore, we develop digital innovations to support the reuse of concrete, a ubiquitous construction material that represents 7-8% of global C02 emissions. 

In this poster, we present our research progress concerning two refereed publications presented at eCAADe and EC3 & CIB W78 conferences, both published in 2023. 

Tracking of building components can be instrumental in reuse for a Circular Economy. Tracking technologies (TT) for building components can be used to identify and access information for decision-making from deconstruction to design for reuse. Prior research has mainly been concerned with single technologies, limited life cycle applicability and new construction. This study aims to explore the potential of combining multiple technologies, such as QR codes, NFC, and Bluetooth tags, with BIM to support reuse along the life cycles of prefabricated concrete components. The benefits and limitations of choices in TT are examined concerning information integration in circular construction.

In recent years, there has been a growing interest in adopting circular approaches in the built environment, specifically reusing existing buildings or their components in new projects. To achieve this, drawings, laser scanning, photogrammetry and other techniques are used to capture data on buildings and their materials. Although previous studies have explored scan-to-BIM workflows, automation of 2D drawings to 3D models, and machine learning for identifying building components and materials, a significant gap remains in refining this data into the right level of information required for digital twins, to share information and for digital collaboration in designing for reuse. To address this gap, this paper proposes digital guidelines for reusing precast concrete based on the level of information need (LOIN) standard EN 17412-1:2020 and examines several CAD and BIM modelling strategies. These guidelines can be used to prepare digital templates that become digital twins of existing elements, develop information requirements for use cases, and facilitate data integration and sharing for a circular built environment.

Building information models (BIMs) make it possible to share structured data in the planning and building process and during the live cycle of the building. The models can be enrichened with information in all stages from planning to end-of-life. Predefined information requirements, data structures, and file formats allow the model to be used for design, cost planning, and time scheduling as well as analysis of building performance, and ideally also for facilities management. This chapter describes the possibilities of using application programming interfaces (APIs) to enhance the usefulness of BIM models. This provides the user with the possibility of creating own applications with real time bidirectional data exchange. Of particular interest is the exchange of data with web-based data sources. The applicability is illustrated with examples of environmental analysis based on web-based data and the use of web-based forms to enrichen BIM models with data input from building users.

This paper investigates novel computational methods for Regenerative Design by developing further on the European Daylight Standard EN 17037, to make it useful at both urban and architectural scales. Case studies are evaluated for sunlight, daylight and quality views. A computational method, compliant with EN 17037, is introduced for the evaluation of sunlight. An assessment of daylight metrics, for an office building in Helsinki, with a 300 lux target, demonstrates a 12% difference between spatial Daylight Autonomy (sDA; occupied hours) and Illuminance levels (EN 17037 method 2; daylight hours), 37% between sDA and Daylight Factor (EN 17037 method 1), and 25% between methods 1 and 2. A new computational method for evaluating ‘views’ on the floorplan is proposed that considers ‘view content’ (EN 17037 View Out layers), ‘view access’, the potential viewpoint-based ‘outside distance’, and can be extended to add the ‘quality of environmental information’. Further research directions and use of spatial metrics are discussed for sunlight, daylight, and view quality.