Building Envelope Design Optimization for Embodied and Operational Carbon Emissions
Date
2024-04-29
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Abstract
Building envelope has a substantial impact on reducing greenhouse gas (GHG) emissions in buildings’ life cycle through reduction of both embodied and operational carbon emissions. Envelope design parameters, such as window-to-wall ratios (WWR), exterior wall characteristics, and window performance features, have been shown to significantly impact buildings’ operational energy use and their associated carbon emissions. Additionally, thoughtful material choices can help mitigate embodied carbon emissions from buildings.
This thesis proposes a design guide for high-performance buildings to reduce life cycle greenhouse gas (GHG) emissions by optimizing their building envelope design to minimize both embodied and operational carbon emissions. The research will focus on cold cities with carbon-intensive grids. A hypothetical office building located in Calgary, Canada (AB, Latitude 51°N), serves as the research case study. The study begins with identifying the list of envelope design parameters that can impact building energy use and GHG emissions in cold climates through a survey of recent building literature. It then employs an integrated approach, combining Artificial Intelligence (AI) techniques with energy performance analysis and Life Cycle Assessment (LCA) to generate an extensive database of envelope design combinations with their corresponding output values for energy use and carbon emissions. Finally, the study derives a combination of min-max normalization and a brute force search to identify the design combinations with the optimum output values for i) embodied carbon, ii) operational carbon, and iii) total carbon emissions. Comparison among design combinations with optimum values shows that WWR is the most important design parameter in reducing both embodied and operational carbon emissions. At lower WWRs, the design parameters with the potential to reduce operational carbon emissions, i.e., energy-saving design strategies, can significantly reduce the building's overall GHG emissions. However, certain groups of energy-efficient envelope design solutions, such as employing biogenic insulation materials with increased thickness and selecting cladding materials with lower embodied impacts, have also been found effective in minimizing embodied carbon emissions while reducing operational GHG emissions. Window assembly, i.e., combinations of glass, frame materials, and cavity gas, should be carefully evaluated as a whole system for their thermal performance and GHG emissions. Beyond building envelope design solutions, additional measures, i.e., gasification of building heating energy systems, use of on-site renewable energy systems, and grid decarbonization, are crucial to reduce emissions from buildings and their envelopes. The findings from this study highlight the importance of building envelope and facade design solutions in climate change impact mitigation. It contributes to advancing knowledge in academic and applied research around low-energy-and-carbon building areas. According to the results achieved from the prediction and optimization stage, this thesis offers a set of essential recommendations and design guides that can help reduce GHG emissions from buildings in cold climates with carbon-intensive energy grids and beyond.
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Keywords
Building envelope, embodied carbon, operational carbon, parametric study, artificial intelligence, energy performance, life cycle assessment, optimization
Citation
Badri, N. (2024). Building envelope design optimization for embodied and operational carbon emissions (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.