I think I’m going to have a Science Cafe NH later this year on the topic of building materials and carbon sequestration. I suspect most of it will cover modern lumber technology like cross-laminated timber, since we have so many trees, but I’d like to find a panelist to talk about efforts to improve the carbon-intensive production of making concrete.

The Union-Leader ran a Bloomfield article about one of those efforts: adding hemp to the cement that is used to make concrete. (Article is here)

Cement makers are responsible for about 7% of global carbon dioxide emitted into the atmosphere every year, with copious volumes entering via limestone kilns needed to produce the material. 

While architects and developers have traditionally concentrated on the energy used by their buildings once they’re are standing, it’s actually the materials required in their construction that represent the brunt of a structure’s lifetime carbon footprint. Replacing high-carbon-intensity materials like cement with greener alternatives like hemp can dramatically reduce greenhouse gas pollution.

Hemp fields absorb carbon when they’re growing. After harvest, the crop continues to absorb greenhouse gases as it’s mixed with lime or clay. Hempcrete structures also have better ventilation, fire resistance and temperature regulation, according to their proponents.

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