Good luck with your project!

-AC

I linked to the wrong pdf. It's from this.

And, again, I'm asking about heat flow/thermal mass. I'm not asking you to wax philosophically on your idea of "best". If you don't have anything to contribute, don't post.

Honesty I'm not sure what you're getting at here.

Insulating a basement wall from the outside is always the best. If you insulate you have to worry about where the dew point is going to be. Concrete is basically vapor impermeable. You will have mold growth between your insulation and the wall. You need to be very vigilant about sealing the foam and making sure that there are no existing moisture issues. Outsulating a wall is labor intensive though. You need to dig and plant XPS and then cover and exposed foam with stucco or something to protect it from sun and weed whackers and the like. You could probably get away with just planting it 2' deep or so. Maybe just use 4' x 8' sheets on their sides. I plan on doing this here before next winter. But how are you going to get R 40? XPS is R5 / inch. That's 8" of foam.

I'm looking for something more specific than that. Insulating from the outside is going to happen sooner or later. If you'll check out the pdf in my last post, you can see data someone at MIT came up with when trying to compare different configurations and R-values for insulation and thermal mass. As it turns out, exterior insulation of ~R15 plus thermal mass on the inside is roughly the equivalent of a normal stick built home with insulation of ~R40 in this climate.

Construction isn't too bad either. Most of the front face that I'm insulating is above a deck, so moisture build up shouldn't be a concern there if it's properly sealed. The south facing side otoh does have a lot of dirt around it, so I'm probably going to dig that up and put in concrete so the water can drain, then build the exterior wall above that. It's a pain, but I should do it anyway, and it's not that expensive, just time consuming.

What I was wondering was, is it worthwhile to insulate the interior walls that are earth-bermed? I'm not sure about that, which is why I was asking people about energy flow. I have a feeling no one here would be able to answer my question, so I'm in the initial stages of modeling home energy consumption, which I thought was gonna be a bit more complicated because of the concrete. Fortunately, that MIT paper has a ton of information on R-value equivalent versus climate and thermal mass/insulation configuration, so I just need to figure out how to model all this stuff.

The concern I was stating about moisture didn't have anything to do with drainage issues. Of course you MUST sort that stuff out first. Any living environment will produce moisture. Where's it going to turn back into a liquid as it moves through the wall? If there is a vapor impermeable layer on both sides (foam and concrete) the moisture will be trapped there and things will go south. R - 15 on the outside of a foundation may perform like R 40 above grade. I don't know. It certainly isn't fixed though. Soil temperatures change with the seasons.

I just did a search on the term "Dynamic R-value Equivalent" and in the entire universe of Google (many billions of pages), there were 47 web pages that mention the term.

I guess that puts you right out there on the cutting edge!

Let us know what you find out.

-AC

The house has and will have vapor barriers on the exterior, but why would I put a vapor barrier on the interior?

How do you plan on insulating the wall?

By adding insulation and sheathing to the exterior.

Well then you should have no problem. What I was referring to was insulation on the inside of the wall. In that case I'd recommend R 20 on the outside, especially if it's going to be conditioned space. That's what the BSC is recommending and it seems to be a good rule of thumb.