Someone asked me this and I had an opinion, but not an answer. So, I'll put it to the group:
Situation: Victorian - 3 floors. Currently has window units for AC - possibility of putting in Central Air. Not have AC is NOT an option, although obviously the best.
Let's say money is not a concern (but you can add that in if you want). Needs all three levels covered.
What say you green ones?
Jim
It depends of how many window units they use, and how often they use them. If they are cooling all 3 floors all of the time with window units, a central unit would be better. If cost is not an option, a geothermal system would be the best. If they only cool the room they are in when they are in it, I would say the window units would probably use less energy. What is the insulation like? Is there any insulation?
Wont window units $$ more electricity wise than a central unit.
I would think so.
I'd say central since you are only managing/servicing a single device which can then be closely monitored in terms of temperature setting (programmable thermostat) and maintenance. Also, there has probably been more R&D money spent by the industry improving central air systems to be more efficient than on window units. On top of that, you have control over the duct work to be installed, assuring that is is properly insulated to further increase the efficiency.
Since money isn't an issue, make sure you re-insulate the walls and put in new windows too 
