What is the most efficient way to cool a house?

 central AC w ducts  200 ft x I I/2 ft x 6 in ducts mean more surface not accessed by sunlight,prone to catch dirt mold and bugs,,,,a window unit may be better,,along with window that are snug,raiseable or lowerable at the top to vent heat,,insulateion betw inside and outside should be up tot he job of retaining winter heat,keeping it cool in summer,and sealed from dampness...Show more

Locate it in northern Alaska not in Phoenix....Show more

of the 3 A/C choices you describe, go with Central Air Conditioning with multi-zone thermostats.
This way, you don't have to air condition ( or heat) the entire house if you are not using certain rooms.

And, of course, pay attention to proper wall/ailing insulation and energy star windows/doors along with the proper house placement on the Iot with sufficient roof overhangs and trees that will never interfere with your roof while still providing shade.

We hada small oaktree 16' away from our house. I asked the architect if we should remove the tree and he said no. I was 27 at the time and took his word. Big mistake. That tree grew tall with branches interfering with our chimney flue, our roof and our gutters. So remember, before you know it, trees close to your house do grow and are a nightmare!...Show more

You forgot one of the best ways. Increased wall insulation and high efficiency windows. ...Show more

oh dam, you forgot to spam your HVAC companies name into that...Show more