CRE has to deal with carbon emissions. Regulations want it. Investors want it. Tenants want it. "Cement production is currently the largest single industrial emitter of CO2, accounting for ∼8% (2.8 Gtons/y) of global CO2 emissions," wrote M.I.T. researchers in a 2019 paper.

Why is cement such a culprit? Fossil fuel. The process requires heating limestone to about 1,500 degrees Fahrenheit, at which point you get calcium oxide — the desired material — and carbon dioxide — the greenhouse gas. Then you need to heat clay to between 2,550 and 2.700 degrees to create aluminum oxide, silicon dioxide, and iron oxide. The oxides together make Portland cement and even more CO2.

Something's got to give, and researchers and companies have been looking at many ways to reduce the emissions, often by looking at how to extend cement with other materials to reduce the amount used in concrete without losing significant strength. Sometimes this is attempted through how materials are processed. Those M.I.T researchers were working on using an electrochemical process to manipulate pH values to separate materials, sequester carbon dioxide, and produce hydrogen and oxygen to generate electrical power for heat.