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From: peters@cubsvax.UUCP
Newsgroups: net.misc,net.physics
Subject: Re: Why don't thermostats work?
Message-ID: <167@cubsvax.UUCP>
Date: Thu, 9-Feb-84 20:28:33 EST
Article-I.D.: cubsvax.167
Posted: Thu Feb  9 20:28:33 1984
Date-Received: Sat, 11-Feb-84 05:42:47 EST
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Organization: Columbia Univ Biology, New York City
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Yes, industrial heating systems are inefficient, especially in the summer.

In the winter, one bucks warm peripheral air with chilled air that is free;
that is, it can be taken from outside, and usually has to be pre-heated a
little in cold weather before being used.  This isn't so bad.  In the summer,
however, one cools the periphery with expensive conditioned air, and then
bucks this cooling effect with air which has been pre-heated at additional
energy expense!  (Conditioning of the warm air is necessary to get rid of
the humidity.)

Unfortunately, without this, there would be great temperature gradients as
between an outside wall and the interior of the building.
There are usually trade-offs between efficiency and performance, and this
is an example.

The inefficiency is compensated by the fact that heat-loss is proportional
to surface area;  the lower surface-to-volume ratios of large industrial
buildings -- which is, after all, what causes the problem which the more 
complicated heating/cooling systems are supposed to fix -- 
also makes them inherently more energy efficient than small 
structures like houses.  I believe (though I
haven't seen data) that the heating bill for these large structures will be
lower per square foot of floor space than for, say, a house, other things being
equal.

{philabs,cmcl2!rocky2}!cubsvax!peters            Peter S. Shenkin 
Dept of Biol. Sci.;  Columbia Univ.;  New York, N. Y.  10027;  212-280-5517