A five year, $70 million dollar renovation of the University’s Department of Physics building focused primarily on upgrading the 6 - story structure’s 50 - year - old HVAC system. While most of the ductwork was replaced, this was not an option for two of the main exhaust shafts, which were part of the building’s structure itself. Significant leaks in these shafts were making proper air system balancing impossible. That, in turn, caused exhaust issues and added substantially to the building’s energy consumption. University engineers knew that Aeroseal was highly effective at sealing metal ductwork, but could it actually seal leaks in old brick masonry shafts?