And I have natural ventilation, but I always try to do so that there is no unnecessary noise.
This situation is highly dependent on your neighbors and the crime in your area.
If there are more than 100 video cards in the room, then many miners prefer to use security.
this is a really good setup, natural ventilation = lots and lots of space
real estate is far more expensive than AC'ing your rigs, but if you have those already or renting it for cheap..then you win.
General rule of thumb is that your AC unit should be at least as many watts as your rigs.
That is interesting, I have never heard of that, as far as I know, 1 watt = 3.4 btu, so if your ac is 12.000 btu then you could cool down up to 3529 watts. Anyway, I'm not against using ac, people need to calculate if is worth and this topic comes up a lot when profit is very high. When profit is low or negative nobody talks about ac ehhe because there can't be any margin of error and if there is then you are screwed --> out of business hehe
12,000 btu cools 3529 watts if nature favors you, if not then that 12,000 btu might just cool down around half of that (rule of thumb of the other guy). the (+/-) ~40-50% margin of that is huge. climate has a huge role.