Today the doors to the new Science Hall at SUNY New Paltz are really hard to open.   There is a howling sound as wind screams its way through the cracks between the doors, which goes away temporarily as you open the door (if you can!) and returns immediately when the doors close.

The problem is that the air pressure in the building is much lower than the air pressure outside.   The doors open outward, so the extra force of the atmospheric pressure pushes against the doors to hold them closed.   This building literally sucks!

This is causing another interesting phenomenon.    In one place where air is shooting through a crack under a door it is causing ripples in the floor mats, as shown in this video taken by someone else in our building.

 

Since this is the PHYSICS building I decided to make some measurements.   I used a Vernier Gas Pressure Sensor (Model GPS-BTA) connected to a Vernier LabQuest .  (I wanted to use the newer LabQuest 2, but the one we have had  a bulge in the backside which turned out to be a swelling Lithium Ion battery.  Danger!)   Repeated measurements inside and outside yield a pressure difference of about  0.03 psi.

That may not seem like much, compared to an atmospheric pressure which is, on average, about 14.7 psi, but from this small difference you can compute the extra force pushing on the door.   The exterior doors are about 3 feet wide and 10 feet tall, giving a surface area of 30 ft².   There are 12×12=144 square inches in every square foot.   Thus

30 ft² × 144 in²/ft² × 0.03 lbs/in² = 130 lbs

That means the exterior doors have over 100 pounds of extra force holding them closed.   No wonder they are so difficult to open.

As I was writing this I grabbed the pressure sensor to verify the model number, and I noticed the pressure here inside the building was closer to that outside. And sure enough, after reporting the problem to our Facilities Office the HVAC was just shut down, and I could  even see the pressure rising slowly to match the outside air pressure.

So our building no longer sucks.

(Actually, it’s quite nice, but there are still a few kinks getting worked out.)