I'm planning a a small home, roughly 525 s.f. in Parker County TX. It has a basement and small loft at either end, and will have a south/north positioning. Here's the question: Given that it will have 9" ICF walls, triple-pane windows, and 5'covered wraparound porch, what are my chances of being able to live comfortably with no central air conditioning installed? Is is there any way to get a rough estimate of what the indoor temperature would be?

I encourage you to also investigate how much it would cost to run AC. Not much with a well insulated/sealed, small house where you block most window solar gains.

Probably not that much, but I was really trying to go totally off-grid solar.

That's doable. For example, a Chiltrix heat pump putting chilled water into a large water tank (only during sunlight hours). Add maybe 2KW of panels to power it.

Semi-passive cooling can be done with lots of internal thermal mass and night-time use of a whole house fan. But it's limited by how cool it gets at night and doesn't address humidity. And the fan would run from battery power.

Throw a $250 window AC unit in as needed......500 sqft is not that much area....no ducting needed?

Look at the efficiency of some of the smallest ductless mini splits like Fujitsu 9RLS3 pumps, it is pretty incredible.  33 SEER. 
The max running wattage of the 9RLS3 is 500 watts but that's probably at full power. 


http://www.fujitsugeneral.com/us/residential/support/downloads/halcyon/submittal-sheets.html

Honest answer: No, you can't live without AC. It's misery, because in summer we have both high humidity and little night cooling.

You can do off-grid and solar, but you'll spend a LOT to do it. Simply put, your system has to deal with surge when the unit kicks on.

We're getting close, though. Small but efficient AC, cheap panels, better batteries. But AC is still the bane of solar.

You can get an expert opinion on just how much solar you'll need and what the obstacles are at Arizona Wind Sun Forum.

> mini splits like Fujitsu 9RLS3

Also inverter based, so no starting surge.

OK, but don't install any of them without surge protection, especially the Fujitsu.

What if the house was built mainly underground, like a walkout basement? with the ground on 2-3 sides and the bottom/floor it should couple with the earths temperatures in theory

It's been done, but above ground houses are typically more cost effective.

Also consider building a small, super insulated, air sealed, high thermal mass, windowless room with AC (and small ERV) in it. It would be a place to read/watch tv/sleep comfortably. Running from batteries is doable, especially if you over-cool it while the sun shines.

Have you looked into "Earth tubes"? I'm in Wise county TX and I'm going for NetZero energy (I have grid-power) so for a while I considered going without A/C. Earth tubes seemed to be a good option, but there does seem to be some controversy regarding their effectiveness. If you don't get crazy with it they wouldn't be too expensive. The reason I didn't use them is because my land is primarily flat so I didn't have a spot to put the inlet while allowing for a decent slope in the pipes, to keep moisture/mold from collecting.

The main problem with the earth tubes isn't mold/moisture.

It's dust and "critters" (I hates me some critters).

If you're aren't meticulous about your screening setup in those things, you never know what's gonna crawl out of them when you open the door on the cooling tube.

And, as I said, dust.

You can cut down on that a bit if you build a filter enclosure on the far end.