<i>You also aren&#x27;t going to put a fleet of little one-ton units on the roof</i><p>Sure you are! Or, well, you could. I lived in Chicago condo that had 20 or so one-per external units on the roof.<p>Some arguments in favor of this approach here:<p><a href="http:&#x2F;&#x2F;buildingscience.com&#x2F;documents&#x2F;digests&#x2F;bsd-110-hvac-in-multifamily-buildings" rel="nofollow">http:&#x2F;&#x2F;buildingscience.com&#x2F;documents&#x2F;digests&#x2F;bsd-110-hvac-in...</a>