My cabin is in north Texas (aka Hell’s Furnace) and is 16x24. I have R19 walls, R25 ceiling, and R20 floors. The walls are 2x6 and I have 7/16 OSB sheathing and Tyvek wrap between sheathing and siding. There are two high quality fiberglass doors, and 4 high quality windows, 2@ 36x48, 1@24x36, and 1@12x24. There is one bathroom 6x8 ft where the 12x24 window is. The attic is vented with a ridge vent and vents are in place under the overhangs. Interior walls are 1/2 in drywall. Ceilings are 8 feet.
So having said all that, I am probably going to buy a window unit rather than a portable. From what I hear and research, they’re just better all around.
As far as sizing the unit, the boxes say 10k BTU is appropriate, and a calculator I found said 13k, but that’s seems right for normal places, not the sweltering sauna that is the Lone Star State in the summer. I figured I’d go to 14K. Does this make sense?
Also how is the quality of the big-box window units? Especially the GE models?