You also aren't going to put a fleet of little one-ton units on the roof Sure you are! Or, well, you could. I lived in Chicago condo that had 20 or so one-per

You also aren't going to put a fleet of little one-ton units on the roof Sure you are! Or, well, you could. I lived in Chicago condo that had 20 or so one-per external units on the roof. Some arguments in favor of this approach here: http://buildingscience.com/documents/digests/bsd-110-hvac-in-multifamily-buildings http://buildingscience.com/documents/digests/bsd-110-hvac-in...