Todd Holland: The greenest option

Thursday, October 28, 2021

As an Amherst resident, I want to be sure our new library is a financially responsible investment, a step toward sustainability, and a key to honoring our carbon commitment.

As a mechanical engineer with four decades of construction experience, I was pleased to serve on the Jones Library Sustainability Committee to help make it so. This project is unprecedented because it considers embodied carbon and not just operational carbon in the design process.

The option in front of the voters is the greenest option. Choosing building materials is one of the largest variables in the carbon equation. The baseline design used concrete and steel. But the massive energy inputs required to make and move those materials would have created a huge carbon footprint, one that even a highly efficient building would take years to erase.

With wooden timber construction, the embodied carbon will be less than one-third the baseline. While far-out solutions to climate change imagine massive machines to pull carbon from the atmosphere and store it underground, this project will take advantage of an existing solution — trees. Trees pull carbon from our atmosphere, and building with wood will sequester that carbon, potentially for centuries.

I know this because my house and garage were built from timbers salvaged from structures built in 1868 and 1887. The carbon in those timbers was pulled from the atmosphere some 200 years ago and is still sequestered today.

If the library had gone forward with the earlier design, the embodied carbon would have taken more than 30 years of operational savings to offset. The carbon savings after 60 years would be 4,500 metric tons. That is not insignificant, but the project before the voters will do far better. The proposed Jones Library will save 7,500 metric tons of carbon emissions in the next 60 years.

Its energy efficiency, coupled with its low embodied carbon, will offset the carbon emissions of its construction — and the relatively tiny footprint of demolition — in just over eight years. And from then on it will pay a carbon dividend, year after year.

Todd Holland