Mapping a Structure's Impact on the Environment

Abstract

Historically, the effects of buildings on the environment have been solely evaluated based on mechanical, electrical, and plumbing building system energy use related to daily operations. Structural systems themselves are typically given little or no consideration for environmental effects; yet, in fact, they contribute significantly to the effects of climate change. Structural systems contribute to carbon emissions not only when they are built, but also over their service life, especially if they are located in regions of high seismic risk. The carbon footprint associated with the damage, repair, and partial reconstruction—or in some cases the full demolition and reconstruction—have considerable effects on the environment. The carbon footprint of a building is sensitive to its structural system with results that may be significantly more favorable with enhanced seismic resistance systems such as baseisolation or viscous dampers. Integrating environmental performance with seismic risk provides opportunities to communicate the benefits of enhanced seismic performance with regards to damage mitigation and environmental impacts to owners, developers, and the general public. Since currently available carbon assessment tools do not fully address the long-term environmental impact of structures, especially as it relates to probabilistic seismic damage, the Environmental Analysis ToolTM has been developed and is capable of considering the environmental impact of structural systems over the entire life cycle of the building. The program is capable of predicting carbon emission equivalents at the conception of design simply by knowing the location of the proposed building, the size of the project, the structural material type, and the expected service life. The program is also capable of performing analysis during the later stages of design, for specific project information. The program can be used to evaluate new and existing structures. Several example projects are overviewed and the impact of probabilistic seismic damage on the carbon footprint is evaluated. Furthermore, a cost-benefit analysis considering enhanced seismic systems conducted. The Environmental Analysis ToolTM is also implemented in a parametric environment for the assessment of buildings at an urban-scale. With the generated carbon footprint results, designers and planners can consider carbon emission equivalents of proposed buildings in the earliest phases of design. STRUCTURAL DESIGN RESPONSIBILITIES AND CARBON EMISSIONS The environment is at risk. The structural engineering design profession needs to carefully reconsider the design approaches to structures. Simply achieving life-safe performance level in a major earthquake is not a measure of good design. Structural engineers should strive to minimize the environmental impact of buildings in seismic regions by 898 Structures Congress 2012 © ASCE 2012