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Abstract

This study explores the embodied carbon contributions of Mechanical, Electrical, and Plumbing (MEP) systems in Building C of the BCR-6 project at UBC, focusing on improving whole building life cycle assessment (WBLCA) practices. With growing attention on embodied carbon, particularly in buildings, this research aims to provide a comprehensive perspective on MEP system impacts and guide the future UBC guideline update to better incorporate the MEP system into WBLCA to further support building decarbonization. The project was conducted in two phases. The first phase reviewed current methodologies and tools for MEP embodied carbon assessment, comparing their applicability, limitations, and select the best suitable method and tool for next phase research. Three distinct methodologies - TM65, LCA database and EPD-based, and BIM-based WBLCA—were analysed, leading to the selection of the database and EPD-based WBLCA methodology for its balanced feasibility, accuracy, and data availability. One-Click LCA was chosen as the tool for experimental calculations due to its comprehensive MEP-related database and compatibility with the existing structure and envelope assessment. The second phase involved experimental WBLCA calculations for the plumbing system, supplemented by literature- based estimations for the mechanical and electrical systems. Results showed that the GWP of the plumbing system accounts for roughly 1/10th of the embodied carbon in the structure and envelope. Notably, acrylic shower tubs emerged as a major emissions contributor, indicating a clear opportunity for decarbonization. Through an extensive literature review on MEP system emissions - considering factors like building size, type, refrigerant leakage, and component replacements over the building’s lifespan - we estimate that MEP systems collectively contribute approximately 36% of the building’s total embodied carbon. This underscores the significant impact of MEP systems, particularly mechanical components, on the overall carbon footprint. The analysis of plumbing and MEP systems faced several key limitations. For plumbing, three levels of uncertainty arose from raw data gaps, inconsistent database matching, and EPD variability during emissions estimation. For MEP systems, challenges included data availability and benchmarking difficulties, such as supplier engagement issues, gaps in electrical data, absence of BIM models, and limited WBLCA tool compatibility. Benchmarking was further complicated by the lack of standardized MEP methodologies, incomplete equipment listings, and the absence of MEP-specific benchmarks and residential building data. These issues highlight the need for further case studies to inform future guideline development. Based on our findings, we recommend building a solid data foundation in the short term through proactive stakeholder engagement, systematic record-keeping, and close supplier collaboration. For the mid to long term, we emphasize the importance of partnerships and broader industry collaboration, such as through initiatives like the MEP 2040 Challenge, to enhance both data quality and methodological rigor. Future research should prioritize developing comprehensive MEP embodied carbon guidelines, validating methods through comparative studies, and establishing clear benchmarks for industry standards. Additionally, exploring decarbonization strategies—including the use of low-GWP materials and retrofitting system designs—is essential to achieve long-term sustainability and decarbonization goals. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”