While I have nothing to add to your article, I thought an anecdote from days gone by might be of interest. In another life, I worked in Technical Services for PEPCO in DC and one of my duties was to visit with our commercial customers who requested assistance in understanding our rate structures. I also regularly visited sites for a “walk through” to provide a second set of eyes and perhaps identify low hanging energy fruit that had escaped notice of the building engineer. A particularly memorable visit was to a venerable, multi-storey apartment structure on Massachusetts Ave. in the city that had been built well before the era of mechanical cooling systems.

While walking a hallway with the building engineer, I inquired about the grated, and now enclosed, transoms above each apartment door and he said, “You have got to see this”. Deep in the basement he showed me an ancient fan, that we were able to step into and I marveled at the size, which had to be over 10′ in diameter. A duct system connected the 75hp air mover to all hallways and when operated, depressurization drew air through apartment windows and out the transoms. While doing nothing to mitigate brutal summer DC humidity, I’m sure the air movement provided a welcome, modicum (small “m”) of relief to the beleaguered tenants.