Green design has long been a result of a number of factors, coordinating the expertise of the project's stakeholders, and guided by sustainability certification programs. However, now, a lot of that can be captured in the design portion with this new software being developed by MIT.

Typically, when architects or engineers design a new building, it’s only at the end of the process — if ever — that a lifecycle analysis of the building’s environmental impact is carried out. And by then, it may be too late to make significant changes. Now, a faster and easier system for doing such analyses could change all that, making the analysis an integral part of the design process from the beginning.

The new process, described in the journal Building and Environment in a paper by MIT researchers Jeremy Gregory, Franz-Josef Ulm and Randolph Kirchain, and recent graduate Joshua Hester PhD ’18, is simple enough that it could be integrated into the software already used by building designers so that it becomes a seamless addition to their design process.

Lifecycle analysis, known as LCA, is a process of examining all the materials; design elements; location and orientation; heating, cooling, and other energy systems; and expected ultimate disposal of a building, in terms of costs, environmental impacts, or both. Ulm, a professor of civil and environmental engineering and director of MIT’s Concrete Sustainability Hub (CSH), says that typically LCA is applied “only when a building is fully designed, so it is rather a post-mortem tool but not an actual design tool.” That’s what the team set out to correct.

“We wanted to address how to bridge that gap between using LCA at the end of the process and getting architects and engineers to use it as a design tool,” he says. The big question was whether it would be possible to incorporate LCA evaluations into the design process without having it impose too many restrictions on the design choices, thus making it unappealing to the building designers. Ulm wondered, “How much does the LCA restrict the flexibility of the design?”

Measuring freedom of design

To address that question systematically, the team had to come up with a process of measuring the flexibility of design choices in a quantitative way. They settled on a measure they call “entropy,” analogous to the use of that term in physics. In physics, a system with greater entropy is “hotter,” with its molecules moving around rapidly. In the team’s use of the term, higher entropy represents a greater variety of available choices at a given point, while lower entropy represents a more restricted range of choices.

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