Nick Mueller wrote:

Pete C. wrote:

An insulated container that is kept at a controlled interior temperature
will not experience this issue any more than a house maintained at a
controlled interior temperature will.

Sorry, wrong.
You do have a temperature gradient looking at a section through the wall. At
the place where the temperature drops below the dew-point, you'll get
condensation. Preferably, that happens within the insulation-material,
supposing it can retain and transport humidity. If that is not the case you
get condensation. And this will be exactly at the inside of the metal
container. Styrofoam and that stuff glued to the inside of a wall is *the*
*worst* you can do. Except you are out for mushrooms.

Moisture doesn't magically appear to condense, it has to come from
somewhere. Neither the steel container, not extruded polystyrene
insulation are permeable so nothing of significance is going to happen
in the space between them. The interior surface is very unlikely to be
at dew point in a conditioned space so nothing is likely to happen there
either.


The difference to a house is, that the dew-point is *in* the brick-wall (oh,
you know what this is? G) and the brick can transport humidity to the
outside, especially if there is a humidity-stopping layer (or not as good
transporting, or much longer distance) on the inside of the wall. You get a
much better climate and much less humidity this way. No dehumidifier
needed.

Again with the steel container, EPS insulation and FRP paneling you have
a triple layer vapor barrier. Moisture outside stays outside, moisture
inside stays inside (normal vents remove it).


The only
source of moisture in the container will be one human intermittently
working in it, something normal ventilation will readily handle.

Sorry, wrong again. Relative humidity is the point. Warm outside, cool
inside and you ventilate - moisture inside. Just have a look at the water
running out of A/Cs.

Look at moisture running out of an A/C after it has been running in an
enclosed space for a while, and dehumidifying the space. Unless you're
doing something really stupid to allow a lot of moisture into the space,
it will remain dry and the A/C will operate more efficiently since it
won't have the added load of condensing moisture out of the air as well
as cooling the air.