The following is excerpted from the Carbon Working Group's upcoming white paper:
The embodied impacts associated with building materials (including structural materials and other finishes and equipment) comprise a relatively small part of the total environmental impact over the life cycle of a structure, with impacts from heating and cooling typically far outweighing the materials impacts. In North America, the relative life-cycle carbon emissions due to building structural materials alone can range from 1 to 16 percent for a 50-year building life, depending upon the building type, energy efficiency, and location.
However, a study of demolition records found that over 60% of the demolished concrete buildings were less than 50 years old, and roughly 10% were less than 25 years old. The numbers were even more striking for the steel-framed buildings: more than 80% of these buildings were less than 50 years old when demolished, and 40% less than 25 years old. For these short-lived buildings, the embodied impacts of the structural system could easily exceed 1/3 of the total life-cycle building impacts for buildings that are highly energy efficient.
The green building movement has primarily focused on improving operating efficiencies to reduce carbon emissions, and building energy efficiency is likely to improve. As a result, the relative embodied impacts of building materials will likely grow. To decrease our risk of exposure to disastrous climate-related events, we must not only reduce emissions from building operations but also reduce embodied emissions in building materials including structural materials. The success of this task depends in large part upon structural engineers who understand the emissions associated with the materials they use and who can use data, design, and material research to reduce the carbon emissions associated with their projects.
So structural engineers are faced with both a challenge and an opportunity.
Use this site to learn about structural design's contribution to climate change, and become part of the movement for solutions.