From: nicksanspam@ece.villanova.edu
Newsgroups: misc.consumers.house sci.physics alt.home.repair sci.engr.heat-vent-ac
Subject: Re: Efficient use of Air conditioner
Date: 22 Jul 2004 06:55:45 -0400

 wrote:

>> Joseph Meehan  wrote re:
>
>> >...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.
 
>Take a given volume of air at 90 F and 40%.

Why 90 F and 40%?

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

Depends on the volume :-)

>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.

>...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)? 

Nick