Structural Materials and Global Climate: A Primer on Carbon Emissions for Structural Engineers

Sponsored by the Sustainability Committee of the Special Design Issues Technical Administrative Committee of the Technical Activities Division of the Structural Engineering Institute of the American Society of Civil Engineers. Structural Materials and Global Climate is a primer on greenhouse gas emissions for the structural engineering community, focusing on the impact of structural materials and systems. Building construction and use contribute more than 40% of human-caused emissions of greenhouse gases. Structural engineers can play a leading role in reducing carbon emissions by designing structures that emit fewer of these gases during construction, throughout building use, and at end of building life. This report explains the science behind climate change and practical ways structural engineers can help reduce the carbon footprint of buildings. The report sets the stage with an introduction and overview of climate change science. It then examines how buildings contribute to climate change and introduces life-cycle assessment (LCA) methodology. The report reviews the variability and uncertainties associated with LCA, and then explores LCA data sources and tools, as well as how LCA is incorporated into green rating systems and codes. The carbon dioxide impact of five primary structural materials (concrete, masonry, structural steel, wood, and fiber-reinforced polymers) are assessed, with guidance on how structural engineers can reduce that impact. A final chapter demonstrates how LCA may be used to understand the carbon dioxide impact of three alternative structural floor framing systems. Structural and architectural engineers, as well as architects, construction managers, and building owners, will consult this report for accurate, practical recommendations on reducing emissions that cause climate change.

Table of Contents:
Preface Contributors Abbreviations and Acronyms 1 Introduction References 2 Climate Change Why it Matters Greenhouse Effect Rising Concentration of Carbon Dioxide Carbon Dioxide Buildup Global Warming Potential Carbon Dioxide Equivalent (CO2e) Embodied Energy and Carbon Footprint Accelerating Factors References 3 Contribution of Buildings to Climate Change References 4 Uncertainty of Carbon Footprints: Data Quality and Variability Data Quality Data Variability Conclusions/Recommendations References 5 LCA, Data Sources, Tools, and Rating Systems LCI Data Sources LCA Tools Building Codes, Standards, and Rating Systems Environmental Product Declarations References 6 Concrete Carbon Dioxide Emissions from Cement Manufacturing Calcination Emissions from Burning Fossil Fuels During Cement Manufacturing Concrete CO2e Emissions Total CO2e Emissions from Concrete Use Carbonation and Accounting for CO2 Uptake Reducing CO2e Emissions in Design Alternatives to Portland Cement Concrete EPDs References 7 Masonry Size of Market Manufacturing Process Carbon Dioxide Equivalent (CO2e) Emissions Environmental Product Declarations Strategies for Reducing CO2e Emissions References 8 Steel Products Steel Production Life-Cycle Stages Structural Steel Steel Reinforcement Cold-Formed Steel Products Specifying Sources of Steel Products with Lower CO2e Emissions Product Category Rules and Environmental Product Declarations Data Summary References 9 Wood Types and Characteristics of Lumber Today Sourcing of Wood Products CO2e Emissions at Each Life-Cycle Stage Wood EPDs Reducing CO2e Emissions in Design References 10 Fiber Reinforced Polymers About FRPs Carbon Dioxide Equivalent Life-Cycle Stages Functional Equivalence References 11 Examples Appendix Functionally Equivalent Material Comparison Index