Life Cycle Assessment (LCA)
A method for calculating a building's total environmental impact across its entire life span, from raw material extraction and manufacturing through construction, operation, and eventual demolition, combining a building's embodied carbon with its operational energy use into one comprehensive picture rather than evaluating each separately.
Why it matters
Optimizing a building's operational energy performance in isolation can sometimes increase its embodied carbon, thicker insulation or additional mechanical equipment both carry their own manufacturing footprint, an LCA is what actually reveals whether a given design decision reduces the building's total lifetime impact or just shifts it from one category to another.
On a real project
A design team runs a whole-building LCA comparing two envelope options, finding that a proposed high-performance assembly's manufacturing footprint outweighs its operational energy savings within the building's expected service life, information neither an embodied carbon calculation nor an energy model alone would have shown.
Who this matters most to
A Sustainability/LEED Consultant runs or reviews the LCA to guide major design decisions, typically working alongside the project's energy modeling to see the complete picture.
Where this goes wrong
A design team runs an LCA comparing two structural systems but sets inconsistent system boundaries between them, including one option's end-of-life demolition and transportation stages while leaving those same stages out of the other option's analysis. The mismatched comparison isn't caught until a third-party reviewer reruns the assessment with matched boundaries and finds the original conclusion actually reverses once both systems are evaluated on the same basis.