Life Cycle Assessments (LCAs) didn’t start with buildings. Coca-Cola was one of the first companies to use them in 1969, likely to justify the use of disposable containers. According to “A Brief History of Life Cycle Assessment,” the Coke study “laid the foundation for the current methods of life cycle inventory analysis in the United States. In a comparison of different beverage containers to determine which container had the lowest releases to the environment and least affected the supply of natural resources, this study quantified the raw materials and fuels used and the environmental loadings from the manufacturing processes for each container.”

LCAs are used today—for less devious purposes—for all kinds of products and, of course, buildings. In their excellent guide Life Cycle Assessment for Buildings: Why it matters and how to use it, One Click LCA defines an LCA as “a science-based methodology for quantifying the lifetime environmental impacts of a building. It is used to measure and reduce the embodied, operational, and whole-life carbon of buildings. It is often needed to achieve green building certifications and comply with regulations.”

An entire industry has grown up around LCAs for buildings, with companies like One Click LCA and EC3 providing software for architects and builders, consultants producing Environmental Product Declarations (EPDs), companies complaining about EPDs revealing dark secrets, and some state governments beginning to demand LCAs on every building—California, Minnesota, and Colorado have passed regulations that demand carbon calculations and LCAs.

It seems complicated and scary, but it all boils down to some basic principles.

Start with scope

What do you want to measure? A full LCA will track and measure a product’s environmental impact from “cradle to grave.” According to the European Environment Agency, an LCA “considers impacts at each stage of a product’s life cycle,…