In our field we frequently deal with applications where we use wall penetrations to relieve and intake air. It could be the need for bathroom exhaust, makeup air intake, emergency purge exhaust, or even general building pressure intake or relief. For this case-study, it is for emergency generator intake and exhaust at a new-construction project for the Erie County Medical Center. If the building loses power and the emergency generators are required to kick on, the dampers will open to allow combustion airflow into the space. 

For this application the dampers will be closed 99% of the time. The space within is still conditioned (heated and cooled) and energy loss through wall penetrations can be great if not properly considered with a preventative approach. This was a legitimate concern for the design engineers. The wall cavity sections at ECMC are large - roughly 100 square feet a piece. They know that in order to maintain a high-performing energy system they will need to minimize all wasted energy through this area.