i've installed 2 Panasonic Inverter aircons, one 2hp for my living room, and another 1hp for my parents room. The 2hp one is the newer Econavi model.

Haven't really tried it out yet as my house is very dusty from kitchen cabinet installation, but it looks really nice. paid the extra for Inverter models as I preferred the looks, won't ever recoup the extra costs from energy savings as I won't be using it that often. at least the gas is more environmentally friendly...

I only know there is a standard rule of word (among the installer)
1 HP is for 12 x 12 feet room.

But actual fact is all about BTU of the air-cond as different brand of air-cond deliver different BTU despite all are rated at 1HP.

BTU required = 12 x 12 x (60~80) (factor which can be varied due to room condition, like insulation, people etc, poor insulation mean higher number, just a rough guess/estimate)

If we take 60.
Then the room require 12 x 12 x 60 = 8640 BTU.

Most 1 HP has no problem to have this BTU.

my ceiling too low... cant install cassett.. else it will be great choice.

Looking into York 3.0hp non inverter.

Cos i'm told that inverter actually blast full power until it reaches the desired temp. For a living room, it wont be efficient, infact it will even cost more.