Data Delivery for Standardizing Sustainable Whole-Building Lifecycle Assessment Using the Proposed OpenBIM Framework

The built environment is responsible for more than one-third of global GHG emissions [1] and generates about 40% of the world’s total annual CO₂ emissions [2]. Of this, 27% comes from the energy used to operate these buildings, and 13% comes from the materials and construction processes used to build them [2]. Buildings are significant contributors to rising carbon emissions and are responsible for approximately 37% of global energy and process-related GHG emissions [3]. It is estimated that by 2040, two-thirds of the global building stock will consist of existing buildings, which will continue to be substantial contributors to GHG emissions [2]. Also, for new buildings, the global building floor area is expected to double by 2060, to about 2.6 trillion ftt² (240 billion m2), equivalent to adding a city as large as New York every month for 40 years [3]. Thus, the built environment significantly contributes to global emissions, necessitating urgent mitigation strategies and sustainable construction practices to address the ongoing and future impact of increasing emissions.

The wbLCA, also known as Life Cycle Assessment (LCA) for buildings, has emerged as a vital method and is considered the most suitable way to assess the environmental impact of buildings [4]. The wbLCA consists of all building lifecycle stages, from production through construction, operation, and the end-of-life stage. This comprehensive approach enables the assessment of the impact of building-related activities on the environment. However, despite wbLCA being suitable for measuring and evaluating buildings’ environmental impacts, in practice, the evaluation of buildings’ wbLCA is solely reliant upon the sustainability certifications and green buildings requirements, such as BREEAM, LEED, etc., and is often neglected [5,6]. Additionally, the data needed for LCA are dispersed and often not prepared for direct use, requiring the analyst to assume, reproduce, and manipulate data to use existing information for assessment and analysis. These certifications are based solely on selected criteria with predefined thresholds and reference values and do not reflect the full life cycle of buildings. They evaluate building performance by comparing selected criteria against predefined thresholds or reference values. The main drawback is that these systems are not comparable due to several disparities in system boundaries, indicators, reference values, and calculation methods. Furthermore, these assessments are time-consuming, require extensive documentation for compliance, are costly, and often require experts recognized by the certifying organization to conduct them and achieve certification. Lorch (2017) [7] notes that the use of such systems in buildings has not led to significant reductions in CO₂ emissions. The wbLCA tools in the current market, such as Athena, Tally, one-click, etc., do not precisely use consistent resource and materials databases, resulting in varied results depending on the software platform [8] and typically do not provide harmonized benchmark reference values as they rely on different criteria in their assessment [5].

Over the last few years, significant efforts have been made globally to decarbonize buildings. Policies, regulations, and strategic goals are defined to reduce carbon emissions in the building and construction sector. The Paris Climate Agreement set a strategic goal of achieving zero embodied carbon in the building sector [9]. Architecture 2030’s goal is to reduce embodied-carbon emissions from all new buildings, infrastructure, and associated materials up to 65% by 2030, and to zero by 2040. Additionally, various standards have been published to enable reductions in GHG emissions. For instance, EN 15978:2011 Sustainability of construction works-Assessment of environmental performance of buildings, ISO 21930:2017 Sustainability in building and civil engineering works, and ISO 21678:2020 [10]. Sustainability in buildings and civil engineering works. In Canada, recent decarbonization practices in the buildings and construction sector emphasize a comprehensive approach that integrates digitalization, productivity enhancement, and low-carbon solutions. Specifically, the National Research Council’s (NRC) platform to decarbonize the construction sector at scale supports Canada’s federal initiatives by advancing a low-carbon regulatory framework and reducing carbon impacts across the construction lifecycle. Through the construction sector digitalization and productivity program, the NRC focuses on digitalizing the construction sector, promoting modular low-carbon solutions, and encouraging performance-based codes. These efforts align with Canada’s decarbonization goals by fostering innovation, improving construction productivity, and supporting the transition to sustainable building practices, all of which are essential to meeting the country’s carbon reduction targets [11].

To achieve a reliable wbLCA, a reproducible, transparent benchmarking method is necessary. To do so, it is essential to establish reference values and benchmarks; having this information enables the evaluation and assessment of the environmental impact derived from wbLCA. [12,13]. Carbon Leadership Forum (2024) [14] defines benchmark as “a reference point against which comparisons can be made”. Using this definition in the context of this study, a benchmark value can effectively serve as a reference point or range to enable comparisons among different models. On the other hand, benchmarking refers to the process of assessing and comparing the wbLCA of a building against these benchmark values. The wbLCA benchmarking provides a consistent and transparent framework for evaluating the environmental impacts of buildings and supports the development of effective strategies to reduce resource use and associated environmental impacts in the building sector. Moreover, wbLCA benchmark development enables setting realistic targets towards a more efficient use of resources and the minimization of related ecological impacts.

This paper aims to address the challenges of data quality and requirements in wbLCA by proposing a framework for standardizing data and model submissions in accordance with BIM standards, thereby extending their applicability to wbLCA as the industry increasingly adopts digitalized solutions for permitting and compliance checks. By adopting openBIM standards, the framework facilitates the standardization of input information, thereby enhancing the accuracy and reliability of wbLCA benchmarking. The significance of this study lies in its use of openBIM and in defining the Level of development (LOD), leveraging digital building models to improve data standardization, integration, and interoperability, ultimately boosting the overall efficiency of the wbLCA process.

The focus of this paper is solely on the conceptualization and detailed specification of the utility of openBIM-based data delivery for benchmarking and comparison. However, within the scope of this work, empirical simulation or case study validation is not covered and is expected to be addressed in future work.

Diversity of wbLCA benchmarking is known in both academia and industry [15-17]. In some instances, in Canada, the city of Vancouver published an absolute embodied carbon intensity value of 400 kgCO₂e/m² [18], and the city of Toronto defined an absolute embodied carbon intensity of 275 kgCO₂e/m² for commercial and residential buildings [19]. However, the defined benchmark values are not comparable, as the information used to identify them and the sample size (buildings studied to determine the benchmark values) are not standardized. A study by the University of British Columbia [20] on multiple buildings confirms this statement. It states that the wbLCA obtained from multiple buildings is generally not comparable, as there are numerous factors such as scope, data source, Bill of Materials (BoM) generation method, and tools. Gervasio et al. [16] and Feng et al. [21] address the complexity of data collection from buildings that limit the scope and accuracy of benchmarking values in terms of accuracy, consistency, measurability and verification as a significant barrier in the development of benchmarks for wbLCA. Additionally, the California Carbon report, which studied 30 buildings over a 60-year period, found a median lifetime total carbon value of 730 kg CO₂e/m² and revealed significant correlations between building type or categorization and higher or lower embodied carbon impacts [14]. Without wbLCA standardization, wbLCA results can be inconsistent and non-comparable, hindering efforts to reduce GHG emissions in the building sector. In other words, since the wbLCA benchmarking method heavily relies on standardizing both its methodology and the information used to determine the benchmarking value, a holistic and standardized approach to wbLCA benchmarking is needed.

Current practices in wbLCA involve various methodologies and tools, such as the Athena Impact Estimator for Buildings, One Click LCA, SimaPro, and GaBi. The availability of such tools enables users to perform LCA calculations based on different parameters, such as building shape, size, and types of materials, and to quantify the ecological impacts (EIs) associated with different building materials and methods, using available input information [22,23]. However, the main present challenge is that the input information used by these tools is not consistent, which in turn causes different wbLCA outcomes that are not directly comparable. This inconsistency leads to variations and potential inaccuracies in the reported environmental impacts, thereby undermining the reliability and comparability of wbLCA results. In current practice, benchmark values are defined as the process of collecting, analyzing, and relating performance data from comparable buildings or other types of construction works, typically used to assess and compare performance between or within objects of consideration (ISO21678, 2020). For wbLCA, these values are derived from these tools. However, the benchmarking methods used are also not comparable. On one hand, the input information for each tool is inconsistent; on the other hand, a consistent benchmarking method is not employed to enable comparability of results. Thus, two primary challenges that lead to concerns regarding the comparability and reliability of wbLCA benchmarking are: (1) the lack of information standardization for wbLCA, and (2) inconsistencies in benchmarking methodologies. These challenges are well recognized within both industry and practice. Several resolutions have been proposed to address these issues, which will be discussed in the following sections.

One way to address these challenges is by standardizing information through digital construction processes. With the increasing adoption of Building Information Modeling (BIM) in the built environment, significant opportunities are emerging to use BIM for extended use cases, such as Life Cycle Assessment (LCA), within the construction industry. The BIM Dictionary defines BIM as a set of technologies, processes, and policies that enable multiple stakeholders to collaboratively design, construct, and operate a building or facility in a virtual space. BIM serves as a pivotal tool for standardizing LCA by systematically sourcing the necessary data for assessment and analysis within the BIM environment. It enhances the assessment and management of environmental impacts throughout the lifecycle of buildings. By utilizing open exchange formats and reusing BIM processes across different building phases, users are enabled to perform detailed and advanced modeling. Adopting such an approach can yield significant improvements in LCA, enhancing accuracy, reproducibility, and traceability. Consequently, the utility of BIM for LCA, as it integrates these processes, has the potential to extend to Life Cycle Inventory (LCI) to minimize manual effort and reduce the time required to collect and compile data [24].

BIM standards adoption facilitates and streamlines data exchange among multiple stakeholders by creating a shared language for information exchange. By doing so, it reduces the number of times data needs to be translated [25,26], which often causes data loss. There are multiple tools available for applying BIM, such as Industry Foundation Classes (IFC), Information Delivery Specifications (IDS), the building Smart data dictionary (bsDD), and other relevant best practices, collectively known as openBIM standards [27]. One significant advantage is the elimination of manual LCA data entry, which is very time-consuming [4,28]. While BIM models provide a clear advantage in generating the Bill of Quantities (BoQ), they represent only one of the data inputs required for a wbLCA. According to the terminology and methodology of the European standard EN 15978 [29], additional required data include operational energy and water use, product service lives, transport, as well as maintenance and repair information.

However, it is essential to note that presently most data exchanges between BIM and LCA tools are still done manually [30]. This manual process necessitates further and additional advancements in the integration of these systems to fully realize the potential benefits of openBIM for wbLCA. The current practices mean that building modelers and life-cycle analysis work separately, and the current procedure causes redundancy and loss of information because data is not transferred systematically. While there are numerous methods for BIM-LCA integration, as shown in Figure 1, there is a need for a standardized, systematic approach to utilizing BIM for LCA [31,32]. The literature reviewed suggests that there are inadequate methodological details for implementing BIM for LCA integration; these gaps need to be addressed not only for knowledge organization but also to support decision-making in the construction sector and the built environment, and hence it is considered in its early stages [25-28].

Although the integration of BIM and LCA significantly reduces time requirements and enhances the ability to evaluate environmental performance, several challenges persist. These challenges include methodological issues, such as the lack of standardized methods for integrating BIM and LCA, which makes it challenging to ensure consistency and reliability in assessments. Interoperability remains a significant hurdle, as ensuring seamless data exchange between different BIM and LCA tools is complex. Furthermore, the current state of BIM lacks comprehensive case studies and sufficient data to support robust LCA applications. In addition, the lack of a suitable methodology to allow verifying different material scenarios within the BIM-LCA framework remains a challenge. Research indicates that determining the appropriate level of detail and information required in BIM models for accurate LCA remains to be identified [34].

As indicated in the literature [35], LCA and organizational challenges can be broadly categorized as technical, informational, and functional requirements. In terms of technical issues, software compatibility, data exchange formats, and the technical capabilities of BIM and LCA tools are some of the pressing challenges. As for informational problems, the challenges can encompass the availability and quality of data within BIM models for performing LCA analysis. In the last category, organizational issues include the need for collaboration among stakeholders and the alignment of organizational processes to support the integration of BIM for LCA [30]. The challenges mentioned above are the main hurdles to integrating BIM and LCA.

The utility of BIM for LCA can be approached in two main ways. In the first approach, the necessary information needed for LCA is included in the BIM model itself. One issue with this approach is that models can become very large, but the method ensures that data is retained. In the second approach, Information from BIM is exported to other software and applications. In this approach, the risk of data integration loss remains significant.

The IFC format and other openBIM standards and tools can be leveraged to establish a framework for information exchange. While BIM provides information exchange standards and formats needed for transfer to the LCA application, in practice, the accuracy and quality of this information can vary depending on the building phase. For example, in the early design stages, models often have low levels of geometry (LOG). Research work indicates that the common granularity required for BIM elements and LCI data can be specified at the building element level. At this stage, LCA data is aggregated based on predefined material compositions [34,36].

The IFC is an open, vendor-neutral data exchange format, and it is essential to consider its standard structure to understand which information can be extracted from the BIM model [25]. Using a standard data structure will always restrict how data can be described and used in building performance tools [26]. Therefore, using a standard structure such as IFC requires all relevant software to translate their data into this format, creating a common language for data exchange and enabling standardized data structures in BIM models for LCA analysis.

The following resolution standardizing information via openBIM, the next step is to standardize the wbLCA benchmarking method, facilitated by a statistical method. Benchmarking in the context of wbLCA involves collecting, analyzing, and relating performance data from comparable buildings to evaluate and compare their performance (ISO21678, 2020). This is crucial for understanding the linkage between the economic value of an asset and sustainable development issues, thereby promoting sustainable building practices. However, existing wbLCA benchmarks often fall short of providing consistent parameters and factors, as they are usually developed for whole-building certification systems and do not offer design guidance at the material or element level [37,38]. Additionally, there remains a disconnect between the target values required for the whole-building assessment and the benchmarks for building elements. This can lead to inconsistencies when comparisons between different works are required. To address these challenges, benchmarking values such as limit value, reference value, best-practice value, target value, absolute value, and relative value are used, depending on the purpose and requirements of the assessment [39,40]. To accomplish wbLCA benchmarking, it is recommended to have external benchmarks rather than targeting new buildings against a broader range of buildings and updated construction standards. To develop benchmark models, building stock models need to be used, which are commonly categorized into top-down and bottom-up approaches. The bottom-up approach is preferred for wbLCA due to its detailed analysis capabilities [41].

Existing BIM–LCA methods and tools are not comparable due to inconsistent data requirements, manual, error-prone data transfer, insufficient detailed implementation guidance (e.g., LOD, classification, IDS), and non-standardized benchmarking. In addition to these, the scope is often on components rather than whole-building assessments. Hence, due to the reasons mentioned, the result is often non-comparable. The proposed framework attempts to address such issues by standardizing inputs through openBIM concepts and tools. By adopting these technologies and ideas, automation and data validation are enabled by aligning the Level of Detail (LOD) with functional requirements, facilitating a reproducible benchmarking module for the whole-building scope. This approach maintains a consistent, interoperable, and comparable wbLCA outputs, directly overcoming the shortcomings of prior approaches.

The outcome of this research is the identification and proposal of a framework that standardizes the data required for wbLCA, ultimately enabling the benchmarking of the Canadian building stock. The proposed framework leverages existing best practices and standards collectively known as openBIM standards, which enable data exchange through IFC. It ensures the completeness of data present in the BIM model through IDS authored for LCA assessment and satisfies local requirements, such as those specific to Canada. Additionally, both geometrical and non-geometrical data are validated to meet Canadian regulatory requirements for building construction throughout the entire lifecycle. The advantages of adopting the proposed framework include the use of BIM extended to LCA use cases and, potentially, to other applications. This approach avoids redundancy, increases productivity, maintains the quality and accuracy of submittals, and reduces the time and effort required by authorities for model checking, thereby enhancing collaboration and data exchange.

The literature review highlights several challenges that need to be addressed to achieve effective integration. One of the primary challenges is the varying LODs within the BIM model and across LCA stages. The LOD Specification, based on the BIM Forum 2023 Parts I and II, provides a structured approach to BIM modeling, ensuring that the necessary data is accurately captured and exchanged. By predefining and aligning the functional requirements of LCA analysis with the BIM model LOD at each stage, adopting appropriate BIM model classifications, and using IFC to translate BIM model information to meet wbLCA requirements, information standardization for wbLCA can be achieved. This approach facilitates a more efficient and reliable integration of BIM and LCA, enabling comprehensive environmental impact assessments.

Current procedures are found to have following shortcomings: (a) they often focus on specific building components rather than the whole structure, (b) they rely on annual electricity and water consumption data from similar buildings, which can vary widely, (c) they oversimplify or omit complex construction and renovation processes, and (d) they offer limited automation and interoperability with formats like IFC and gbXML, which do not significantly reduce manual effort. Tools and plug-ins for exporting material quantities from BIM models to LCA are available but limited in their ability to analyze the environmental effects and integrate with BIM tools, reducing their effectiveness in the early design stages [46,54]. The study suggests that building modelers use IDS requirements to identify LOD requirements before and during model development. Compliance with the LOD requirements minimizes rework and the time required to find relevant information during LCA analysis stages. Hence, the framework facilitates the transfer of available information to LCA by connecting it with BIM. This integration builds upon the best practices for enhancing the wbLCA for benchmarking and comparative analysis.

In addition to the issue of data transfer to further implement a standardized benchmark method, there is a need to implement statistical approaches. A dual approach is suggested, with external benchmarks for broader industry comparisons and internal benchmarks for building assessments. This dual approach provides a complete view by integrating top-down and bottom-up models. By doing so, it ensures that benchmarks are relevant to the project and maintain a way for broader comparison, addressing the specific needs of different building components while aligning with broader sustainability goals.

To do so, an adequate sample size must be defined based on the desired precision and confidence level for benchmarking. As suggested by the literature, to harmonize the wbLCA practices, the use of specifications is recommended. For example, OmniClass tables can be used for consistent data inputs. Having uniform inputs allows for broader comparisons and moves toward more reliable wbLCA results and reporting. Ensuring an adequate sample size that meets the desired precision and confidence levels is crucial for reliable benchmarking. The literature underscores the importance of harmonizing wbLCA practices through standardized specifications and, as such, the use of OmniClass tables for consistent data input. This harmonization facilitates the comparability and reliability of wbLCA results. By adopting the standard LOD definitions found in documents such as the BIM Forum 2023 and a dual-approach to benchmarking. This resultant method and framework can provide a robust, standardized approach for conducting wbLCA and establishing reliable benchmarks.