But nobody is buying greener cement because it costs more.

Whenever anyone complains about the carbon footprint of making cement, and how it is responsible for 7 percent of the world’s CO2 emissions, the industry responds saying “we’re working on it!” And it’s true, they are. But as Vanessa Dezem writes in Bloomberg, that doesn’t mean anyone is buying it, or that the customers care.

“There is so far too little demand for sustainable materials,” said Jens Diebold, head of sustainability at LafargeHolcim. “I would love to see more demand from customers for it. There is limited sensitivity for carbon emissions in the construction of a building.”

The article is particularly interesting because it shows that the problem of Upfront Carbon Emissions is finally going mainstream and getting on the radar.

While architects and developers concentrate on the energy used by their buildings, it’s actually the materials supporting the structure that embody the biggest share of its lifetime carbon footprint. Cement’s contribution to emissions is especially immense because of the chemical process required to make it.

Until now, nobody really cared. LafargeHolcim tried selling a carbon-free cement but “Customers were “very price sensitive” and didn’t show interest.”

Low-carbon geopolymer cement, made with fly ash, do not rely on the chemical reaction that makes cement out of calcium carbonate, so it can reduce carbon emissions by up to 90 percent. It costs 3 times as much as cement made from calcium carbonate the old-fashioned way. Meanwhile, it’s hard to believe, but as coal-burning power plants close, the supply of fly ash needed for geopolymer cement is getting tight in Europe and the USA, keeping the price up. But as Dezem concludes:

Without action from policymakers, green cement may remain a low priority for the builders, said Tiffany Vass, who assesses energy technology and policy on the IEA’s industry team. “I don’t believe the pressing need for decarbonization has broadly reached the construction industry in many parts of the world,” Vass said.

Once again, it seems that it will take government intervention, carbon taxes or caps to actually get anyone to change. And because so much concrete goes into housing, the industry will cry “housing costs will go up!” Since governments pay for highways, they will say “taxes will go up!” so nothing will happen.

Add up all the numbers: Making a ton of cement produces about a ton of CO2. It’s then mixed with sand, gravel and water to make concrete. A cubic yard of concrete weighs about two tons and is responsible for the release of about 400 pounds of CO2. About 10 billion tons of concrete are produced every year; the 21 million cubic yards in the Three Gorges Dam are just a drop in the bucket.

Cement production produces more CO2 than all the trucks in the entire world. We have to use less of it.