In sci.physics wrote:
wrote:

Joseph Meehan wrote

...the very high cost of removing the moisture that comes in from outside.

That's a low cost, unless water vapor condenses inside the house.

We were talking about a) ventilating a house at night vs b) keeping an AC
running. I'm thinking a) is better, as long as we don't have condensation
inside the house.

Actually, it was the cost of getting water vapor out of the house that is
in contention.

Take a given volume of air at 90 F and 40%.

Why 90 F and 40%?

Because that's what it was when I wrote it.

It is called a sample problem.

How much energy does it take to cool the air to say 72 F?

Depends on the volume :-)

The volume was "given".

How much energy does it take to cool and condense enough water to get down
to 40% at 72 F?

Why 40%? Standard ASHRAE humans are comfy at 56% and 80.2 F.

It is a sample problem.

ASHRAE humans may be comfy at that, but over 40% is NOT comfy for me.

...Without running through the math, I would think getting the water vapor
out is the energy expensive part.

Try math! If your 32x32x8' house has 6K Btu/F of fast capacitance and 400
Btu/h-F of thermal conductance, including 200 cfm of air leaks, and it's
78% and 71 F in the morning, and the outdoor temp hits 92 in the afternoon,
with the morning humidity ratio, which is better, a) or b)?

If it got to 78%, I would move elsewhere.

--
Jim Pennino

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