How much venting in cold climate passive solar coop

[WthrLady]

that's a half monitor Woods Style coop. Several of us have them on here and they work great!

Here's Mine.
https://www.backyardchickens.com/a/ooodalolly-at-dunrovin-station I'm on the Prairielands of Nebraska so I get the frigid air masses and UNBELIEVABLE winds, as well as roasting heat and humidity in the summer.

 

[CalgaryFarmer]

The thermal mass on the north wall will help. I doubt the concrete floor will help. This will be covered with sand or shavings. Without direct exposure to solar I doubt it will heat up much. As well, a fair bit of the solar heat will probably go to evaporating moisture in droppings etc.

I am considering a soda can heater to pump in heated air. http://www.treehugger.com/solar-technology/how-build-diy-solar-air-heater-old-soda-cans.html If the cans are filled with rocks or similar (but still allow some air flow) then perhaps they will provide some heat into the night.

 

[MeepBeep]

I'm firmly sold on the deep litter...

If I was building a coop from scratch I would highly consider 2 foot tall concrete knee walls in the coop, over the 6" ones you have pictured... And would also move the doors up 1-2 feet above the inside floor and use a step in step out... My existing coop is sunken bellow grade and has 2 foot concrete knee walls and it works well to contain the litter and avoid wall rot,, I built a partition wall in the coop and the door is about 1 foot above the floor, it keeps all the litter inside and I don't find it much of a hassle to just step over...