ICF - Insulated Concrete Forms - Ultimate deer blind

[match]

I am wanting to build a new (maybe 2) new permanent deer-blinds on my land. The first one I want to replace is currently a rotting 5'x5'x5' wood framed, tin sheathed box, sitting on the ground. It is a bit cramped, especially if I want to take my baby boy with me in the future. The smallest bump to the thing (with a muzzle for example) is very loud. It has no windows or insulation and would not make a very comfy emergency shelter. 

I am planning to make a super blind. I am envisioning a 2 story so that I can hunt from up high, have the bottom level to have a bunk and storage, and I am even considering digging out and pouring/cinder blocking a proper basement for more preps. To economize, I am thinking small, at just an 8'x8' foot print with regular height walls, trap doors in the floors for ladder access. 

Best case this would be a great hunting blind comfy in any weather, worst case it could serve as an additional emergency shelter. I'm building a house on the land soon and want to build with ICF construction and I am considering the deer-blind to be made of this type of construction to gain some experience with it, although that might be beyond my budget.

Has anyone thought or done similar? 

[panzer0170]

BLUF: More info needed!

First, and most important question;

What temperature will the blind get used in (average for the month you'll be in it)?

I see where you're going with permanence and insulation, but concrete, brick etc are fantastic thermal stores. If it gets cold it will STAY cold. On top of that you have to take into account how you're sealing windows, if at all, for heat retention. If all you want is a shell you can heat whilst you are in it? ICF may be overkill in terms of cost and construction, AND unsuitable.

ICF for a sealed ground level structure with a different material for the first story would be cheaper, and probably more thermally efficient for how often and how much you're actually going to heat it. (or cool it!)

[match]

Here in East Tx the temperatures could be anything from 20-70 degrees during hunting season when it is likely to be most used. In the summer it of course likely to be 100 degrees.

Good thinking about the thermal mass. That could make things difficult for comfortable short duration use of a few hours. I think I will just do stick built construction as it will be quicker, cheaper, and easier.

[panzer0170]

Wood construction, cloth outer, bubble wrap 'insulation' w/ foil and a cloth inner would do it. small gas fire or convection heater of some kind would bring it up to temp quickly enough, and just throw a pinned heavy cloth over each window for thermal retention.