re: efficient use of air conditioner
22 jul 2004
>> 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)?