Concentration of CO2 in the Atmosphere

Williams College Takes a Crash Course in Window Weatherization

Williams College in Williamstown, MA. (Doug Schlaefer)

Christopher Pratt

The heat that builds each year from carbon emissions is also turning up the heat on sustainability directors and project managers of New England colleges to decarbonize their respective campuses by a 2030 deadline, or else. So, when it came time to decide what to do with some enormous 1912 12-by-12-foot double hung windows at Thompson Science Center at Williams College in Williamstown, MA, sustainability project manager, Doug Schlaefer made an unusual decision. He called up a little window weatherization company in Montpelier, VT named Open Sash, to see if they could weatherize seven of the building’s windows. The work would be a pilot project that could lead to a blueprint for treating all the old windows on campus, if it was successful.

Williams facilities technician, Jason making a deal cut on a bottom rail assisted by Kyle. (Chris Pratt)

As the owner of Open Sash, I was thrilled to get Doug’s call back in the winter of 2021. I had always thought campuses like Yale University, Middlebury College and Williams College should use my window weatherization treatment, but never got a foot in the door or window, even as an alumnus of Middlebury and Yale. In fairness to my alma maters, I have not had a lot of time for networking and outreach. I spend my time working and looking for other people to also do the work. On the other hand, they could have read my article in the NESEA 2021 Quarterly Magazine, Winter edition and called, as Doug had.

Big, beautiful, divided lite windows are a challenge when it comes to decarbonizing a building. They are the eyes and soul of these historic campus buildings and as such are impossible to replicate with modern factory-made windows. More important, the exorbitant cost and carbon-emission life cycles of replacement windows make them a poor choice in the long run. Once you are on the “conveyer belt” of replacement windows, you are then looking at a potential replacement cycle of every 25 to 30 years.

The Open Sash system adds a low-e panel of glass to the outside of the sash, such that it can move up and down freely with the sash. The old window is unchanged and the efficiency is increased 80-90% compared to that of a replacement window. Most important, it is repairable and has a much lower carbon-emission life cycle, which is really the goal of building decarbonization. There is also the option to add an exterior storm window, but they are lacking in efficiency, aesthetics, usability and their carbon life-cycle emissions are higher than the Open Sash Method. Williams had added storm windows years earlier but will now consider removing them, as one less component to maintain. Doug said, “We hope the work to redo the windows will result in less draft complaints and greater comfort in the space.”

I wasn’t able to replace the windows at Williams myself due to labor shortages, especially in the trades, so we opted to squeeze in a training for the Williams trade staff and a local contractor.

Smoothing the cut with a sander. (Chris Pratt)

Williams College Facilities Department is also shorthanded, but they had the tools, space and, most important, enough skilled labor to get the job done. I was happy and able to spend four days training them in my method and passing on the knowledge to as many people who are interested. In my twelve years of running this business, I have taught many new hires how to work on windows, but I have never had a chance to work with such a great group of four experienced and skilled woodworkers. My experiences suggested that it would take a couple of years to train new employees but working at Williams made me realize that this period could be much shorter.

In just four days of teaching and working with the four carpenters, we were able to remove, weatherize and re-install the seven enormous windows. A good deal of the time was spent moving the windows through a labyrinth of corridors, stairs, and elevators. This was an impressive accomplishment and bodes well for the future of old windows and decarbonization of college campuses around New England. We hope other colleges will follow suit and consider this option as a means to reduce emissions, but also allow them to extend the useful life of their older, existing window stock. That is good, because the heat is on to get this work done soon.

Christopher Pratt is the owner and founder of Open Sash Windows. He lives in Montpelier and focuses on the repair of windows for improved efficiency throughout central Vermont. Learn more about his work at

Watch for an upcoming interview with Pratt that will include further details about his methods to save existing windows and can add efficiency and save the waste.

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