Date: Thu, 21 Oct 1999 13:32:26 -0600

Author: Jerry DiMarco

Subject: building design



In our new lecture hall fresh air is more of an issue than temperature.
Whether it's 200 students in a classroom or 20 in a lab, it can start
smelling like a locker room after 1 period. We have asked to get more air
flow into the room, but the powers that be have not budged. So we have
some door-proppers too, and I'm on their side. Think what it's like for
the students, it can't be helping the learning process. We shouldn't be
surprised if some of them fall asleep. If you cannot get the air flow you
need, I recommend that you ask for some additional air recycling or
conditioning. I'd be interested to hear if you come up with a better


At 09:26 AM 10/15/99 -0500, you wrote:
>Some of our faculty, rather than accepting a fixed temperature, and working
>to have it fit *everybody's needs* insist on opening the classroom door to
>adjust the room temperature to their own comfort.
>Now, that seems reasonable until you realize that large classrooms usually
>have their own air handlers. All HVAC systems are controlled by some sort
>of feedback mechanism. The same faculty are acutely aware of the theory
>for such feedback systems, ie, that it will behave exactly like putting a
>microphone in front of the speaker in an amplifier system. So, when they
>open the door because it is too cool, the AC system senses the warm air and
>cools the room even more. If it is too hot in the room, and they open the
>door to cool it, the AC system senses that it is now too cool and heats it
>even more. Duh...
>Once this is realized, the excuses/explanations are nothing short of
>arrogant. A trip to the opposite end of the classroom (from the open door)
>usually reveals a 10 degree temperature difference from the comfort zone of
>the door propping instructor. In cases where the door is left open all
>day, the room is unbearable at one end and just right at the other! Karl


Jerry DiMarco, Instructional Lab Supr. ph: 406-994-6161
Physics Dept., Montana State Univ. fax: 406-994-4452
Bozeman, MT 59717-3840 e-mail: