Re:Why don’t we just open the windows? Covid-19 prevention l...
by chrismorgan on Monday November 29, 2021 @01:45AM
(#29377105)
Certainly the comfort band is the key to it. Everything else is rounding error under even the most pessimistic estimates.
On phase change energies: I don’t know enough to quantify things definitely there, but https://en.wikipedia.org/wiki/Latent_heat#Specific_latent_he... looks like the right thing, and suggests around 2.4kJ/g, which with water being as much as 5% of the air (100% humidity at 40°C) would be as much as cooling the air down by about another 0.12°C for removing all of it.
Re:Why don’t we just open the windows? Covid-19 prevention l...
by mlyle on Monday November 29, 2021 @12:56PM
(#29382879)
Each of the terms is a small single digit percentage, but they multiply together to become a small but noticeable effect on building efficiency.
Re:Why don’t we just open the windows? Covid-19 prevention l...
by chrismorgan on Monday November 29, 2021 @09:00PM
(#29387925)
Each of the terms are single digit percentages if you were completely replacing cool, implausibly bone-dry air with implausibly hot and saturated air. With more realistic ambient and goal saturation, temperature and leakage figures, I think you’re looking at more like single digit hundred thousandths or millionths for most of the terms.
OK, so I should add a little more nuance:
* With more water vapor in the air, the air has a little more heat capacity
* With more water vapor in the air, the temperature band for comfort is a little narrower
* With more water vapor in the air, air conditioners need to work extra hard to provide the same cooling.
That is, the more water there is in the air to begin with, the more will condense and return its heat of vaporization to the room.