Unsustainable Building Entry Doors

All I could think was "Were you born in a barn?" It was one of the memorable lines from my father when anyone left a door open, spilling all the precious conditioned air to the exterior.

When returning to the car after a meeting in Philadelphia, PA, there was no mistaking that blast of arctic air. The ambient air temperature was in the high 90s during an early June heat wave. But what was the source? I turned and headed into the wind.

There it was, the accessible entrance with low energy automatic operators. One door leaf was standing half open. From 20 feet away, it was not just noticeably cool, it was a stiff breeze (easily 10 mph or 900 fpm) of chilled air. I was surprised there was no crowd taking advantage of the respite from the heat.

I couldn't help myself.  I had to investigate.

Even with my help, the door was difficult to close. It is no wonder the closer could not pull the door shut. There were two obstacles: the positive pressure from the lobby HVAC system and zero clearance at the door sweep. The 3 x 9 foot door provided a magnificent sail to catch the HVAC breeze. The door dragged on the threshold which compounded the resistance the closer was required to overcome.

With the door standing half open, the vent area was over 21 sf. At the estimated 900 fpm, that is 19,000 cf of conditioned air lost to the exterior every minute. Hmm...60 minutes per hour, 9 hours a day, five days a week, 52 weeks a year.  Where you born in a barn?  Fix it!