re: webmd: "keeping a cold winter house can harm your health"
28 nov 2001
>but dampness increases the moisture retained within the clothing
>(i'm thinking socks as my feet sweat), decreasing the clothing's
>thermal resistance, increasing the heat loss and making your feet
>feel colder. yes?
maybe. interesting thought. i've read that 2% condensation inside
fiberglass insulation halves its r-value. wool is supposed to do better
when wet. the issue may be whether the dew point temperature (100% rh,
the onset of condensation) happens within the insulation itself (eg
the sock material.) this depends on the rate of water vapor generation
from the foot and the room air temp and rh and the moisture permeability
of the shoe material and how much vapor escapes via the upper edge.
exercise matters. some hiking socks are said to "wick away moisture."
hard to estimate.
we could do experiments. wear socks, then weigh them before and after
drying them in an oven, and measure their thermal resistance with
different moisture contents. i suspect the room rh wouldn't matter
much when people are seated indoors.
for the most part, we treat our bodies like houses, putting the vapor
barrier (skin) on the warm side, with clothes that are much more permeable
to water vapor. we notice condensation inside imperme'able raincoats,
and try to avoid those situations.
some hunters wear vapor barriers (eg latex clothing) next to the skin
to keep warm. l'd guess this works more by reducing the evaporative heat
loss from the skin than by avoiding condensation inside the clothing.
an adventurous woman once told me that she enjoyed having her husband
wrap her entirely in saran wrap. she would struggle, nearly immobile,
and he would torment her by "poking strategic holes in the film." she
said this was only possible on very cold days.
experiments like these can help distinguish between reduction of heat
loss by evaporation from skin and reduction of heat loss by avoiding
condensation inside clothing.
enquiring minds want to know.