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Carbon Blog Series #6


In an LCA of a building, all of the material and process quantities are gathered into a body of information known as the inventory and multiplied with the appropriate impacts for each material or process. The overall results are summed to obtain the overall environmental impacts of a building. A simple example of the calculation process is shown in Figure 2.

How is LCA used in the building industry?
In the building industry, LCA is commonly used to:

• Help building owners make informed choices regarding sustainability and/or resilience
• Evaluate design options by providing insight into materials choices and their environmental impacts
• Achieve green building certifcation (e.g. in LEED v4 or Living Building Challenge)
• Assist in assessing the environmental benefts of new products and/or policy
• State that a system or product is environmentally preferable to another (to make a comparative assertion)
• Compare to benchmarks to evaluate a building’s performance

The results of an LCA can illuminate which parts of a building have particularly high environmental impacts. This type of hot-spot analysis can help the design team achieve a more environmentally conscious design. However, any design modifcation should be evaluated with another round of LCA. For example, changing the structural
material of a building from concrete to steel would afect the insulation design due to the difering thermal properties of concrete and steel. The insulation components would then have to be redesigned before the LCA is performed again. In design practice, LCA can be used as a comparative model aimed at making incremental improvements and evaluating design options. Simply put, LCA helps designers evaluate the environmental consequences of diferent designs by comparing buildings, materials, or assemblies. This iterative process of LCA is expanded upon in the next part of the Practice Guide: Implementation. A preview of the steps for conducting an LCA is shown in Figure 3, which illustrates the iterative process of LCA. The dashed lines indicate the potential paths of iteration through the LCA process.

Carbon Leadership Forum - Life Cycle Assessment of Buildings: A Practice Guide