Root cellar building

We have enough polystyrene blocks (insulated concrete forms) to build a root cellar, but wondering if it would be our best choice of material, given that there could be off-gassing, not to mention the less-than-aesthetic appeal of styrofoam in a food storage room. 

The cellar will be earth-bermed on 2 sides and the ICF's (insulated concrete forms) will probably be covered with something (sheetrock? plywood? mud?) on the inside of the root cellar.

Does anyone have an opinion or experience using this material for a root cellar?

Also we have the book, Root Cellaring, by Mike and Nancy Bubel...
does anyone know of other good sources of info on root cellar design and use???

what about dirt vs. concrete floor?

I have drawn churches and school buildings utilizing ICF's.  I have also drank hot liquids from EPS, I would have no qualms with it.  I would sheath them with something after construction just for durability. 

I'm a draftsman for an architectural firm in CA. 

Humidity is an important aspect of Root Cellaring.
Your construction need to keep this in mind.

Here is a link I had bookmarked on the topic. I'll be following this topic as we are going to build one in the future too.
http://www.livingoffgrid.org/an-ode-to-preserving/

...also I remember reading about two zones in the best design, one with higher humidity, I think this was the dirt floor side.