Shorts and a tee shirt should be sufficient; don't you think?

>It seems as though whenever I see pictures of folks in the Shuttle or at
>Alpha they are always wearing long sleeves and I think long pants, too.
>As it is the case that the thermal environment in those two venues is
>totally under human control, I don't understand why the setpoint is so low
>as to require such heavy clothing. Why not set the temperature at 80F or
>so and have the humans wear just shorts and a tee shirt? Why carry bulky
>clothes? Do they keep it cold so that the electronics stay cool, or is
>there some other technical reason?

It's easier to heat a space vehicle than to cool it. Remember a space
vehicle is essentially a vacuum bottle which can only be cooled by radiation
(if you don't want to waste mass in evaporative coolers). Getting heat out
is a pain, technically. So typically space vehicles are biased to be
slightly more on the cold side than the hot side -- and they'll make up the
difference with a little bit of cheap, light, simple electrical heaters,
which they can control easily.

Populated space vehicles run the same -- they are easier to heat up than
cool, so they'll set the thermostat to a little cooler than hotter, and make
up the difference by wearing long pants instead of shorts -- cheap, simple,
reliable, safe and lighter weight than adding more cold plates, cooling
loops, etc.

As a secondary factor, most space vehicles have lower pressures and
different humidities than you may be used to on the Earth (Shuttle tends to
be pretty dry/ low humidity due to technical factors in the ECLSS system) --
which tends to have a different heat capacity and perception of temperature
in the air. So things cool off easier than in 1 standard atm. This means
while the air may be a comfortable temperature, if you exert yourself, you
will cool off faster -- and its easier to have on a bit more clothing.