A Bills of Materials Dataset for Buildings Made of Mass Timber, Structural Steel, and Reinforced Concrete Using the 2021 International Building Code Provisions

Description

This dataset compiles a bill of material for buildings in the United States made of mass timber (MT), structural steel (SS), and reinforced concrete (RC). The buildings are classified as IVA-18-story, IVB-12-story, and IVC-8-story and are designed in compliance with the International Building Code 2021 (IBC 2021). The Athena Impact Estimator for Buildings (IE4B) was used to generate the bills of material for the Environmental Impact Assessments for the reference study period (RSP) of 75 years (ASTM 2022; EN 2011) and to conduct the whole building life-cycle assessment (WBLCA). Additionally, bills of material and WBLCA for the RSP of 60 years were generated for sensitivity analysis. Due to one of the potential changes in the fire rating in the upcoming International Building Code 2024 (IBC 2024), an additional dataset for the buildings in the category IVB-12-story was created to perform sensitivity analysis to show the different WBLCA results.

Steps to reproduce

With IE4B, the bills of material could be replicated using the designed buildings' layout, assemblies' data, system boundary, functional units, and reference study period (RSP). Layout: The building design used in this assessment is based on the Timber Tower research project. The dimensions and fire ratings of the hypothetical buildings were specifically redesigned to optimize the floor area within the categories of IBC 2021 for R-2 residential occupancies (IV-A-18-story, IV-B-12-story, and IV-C-8-story). Each floor was designed to accommodate a total of 11 residential units. For the present work, the default location selected was USA which was provided in the Athena Impact Estimator for Building (IE4B) software. The buildings were also redesigned to meet the fire resistance requirements outlined in the tall wood building provisions of IBC 2021. Assemblies: To ensure the functional equivalence between MT buildings and buildings constructed with SS and RC, a few columns, beams, and foundation pillars were eliminated for the RC and SS framing systems that can span longer distances. However, demising walls were retained for all structural systems because the division of residential units provides a logical location for shear walls or lateral bracing components that typically resist lateral wind or seismically induced forces. The magnitude of earthquake, wind, or snow loading may vary greatly across geographic regions due to site-specific parameters of soil strength and stiffness, geological and topographical features, or climate, which typically factor into equations used to apply design loads. System boundary and functional units: The system boundary of the WBLCA employed a cradle-to-grave (modules A-C) system boundary. Module D was included in the assessment, while operating energy (module B6) and water (module B7) were excluded. This exclusion was based on the past studies that assumed or identified that the choice of structural materials had minimal impact on building operations but significantly affected embodied carbon and energy. The functional unit adopted for this analysis was 1 m2 of floor area of multistory building for 75 years. Reference Study Period: The chosen RSP is highly sensitive because various factors contribute differently to a building’s environmental impacts over its lifetime, including operational energy and water use, maintenance, repair, replacement, and refurbishment. Different frameworks and methodologies define different RSPs; for example, LEED suggests a RSP of 60 years. The current work follows guidelines from ASTM E2921-22 and EN15978, setting the RSP at 75 years for comparative analysis purposes.

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