Passive Solar GreenHouse Design Input Needed

Greeting!
Would like you all’s input on my green house design I’m getting ready to break ground on. Would like to make the tweaks beforehand so Im not rebuilding down the road.
Goals- to extend our growing season to year around.(is that to much to ask!!!?) grow citrus and other less hardy dwarf fruit trees
-Zone 6b, Western North Carolina elevation 3900’
Design features:
* Footprint 12 x 20’
* Climate battery. Two layers of four inch pipe  blown with 6 inch fans. One pulling hot air from NW and returning cool air to SE. and the other NE and SW . One at 4’ underground one at 2’ depending on water levels. Can I get by with a 4” header for this size battery? roughly 10x18’. Pit will be lined with 4” of ridged board.
* North wall will have a 4’ cider block wall(thermal mass) that short wall and rafters will sit on. Should I fill these blocks with native clay to add mass or leave them hollow? I’m thinking I should.  Theres a point of Diminishing returns if I understand it correctly
* Exterior of north, east, west wall insulated with ridged board.
Interior wall cavities will be insulated with rockwool. And a vapor barrier? What type?
* South wall will be double paned sliding glass door glass. 6 wide titled at 70 degrees on lower pitch and upper pitch is about 23 degrees.
- east west walls will have one small window.
- door on east wall or north east
-windows rabbits into 2x6 frame.
Frame painted with elastomeric white paint.
More questions
- How much venting will I need with climate batteries.
- Where should I locate door?
- Is a vestibule necessary?
- Do I need a vapor barrier on inside as well as outside?

Would like you all’s input on my green house design I’m getting ready to break ground on. Would like to make the tweaks beforehand so Im not rebuilding down the road.
Goals- to extend our growing season to year around.(is that to much to ask!!!?) grow citrus and other less hardy dwarf fruit trees
-Zone 6b, Western North Carolina elevation 3900’
Design features:
* Footprint 12 x 20’
* Climate battery. Two layers of four inch pipe  blown with 6 inch fans. One at 4’ one at 2’ depending on water levels. Can I get by with a 4” header for this size battery? roughly 10x18’. Pit will be lined with 4” of ridged board.
* North wall will have a 4’ cider block wall(thermal mass) that short wall and rafters will sit on. Should I will these blocks with native clay to add mass or leave them hollow? There a point of  Diminishing returns if I understand it correctly
* Exterior of north wall insulated with ridged board.
* South wall will be double paned sliding glass door glass. 6 wide titled at 70 degrees on lower pitch and upper pitch is about 23 degrees.

More questions
- How much venting will I need with climate batteries.
- Where should I locate door?
- Is a vestibule necessary?
- Do I need a vapor barrier on inside as well as outside


I appreciate the input.


I appreciate the input.

Frame painted with elastomeric white paint.

I am not convinced this type of paint in this situation will be worth the expense.

Are you saying no white paint at all or not elastomeric? I am worried about moisture problems and the reflection was bonus.
Everything but the sill plates will be untreated and I will Sho Sugi Ban to preserve the other wood.

I guess I would try to use wood that would not rot in this situation.
Also does Sho Sugi Ban work on any timber, or does the timber have to need particular properties for Sho Sugi Ban to work with it.

As for the paint being reflective, I would need to know the extra cost wqs worth while.

Using 2x6 yellow pine that was left over from another job aka free.
I’ve Sho Sugi Ban many different types of woods. Locust for ground contact posts, pine for board and batten. Fir for pavilion rafters. The cellulose layer which rots first gets charred prohibiting rot and the lignin layer kind of boils. I think any untreated wood is a good candidate for this method of wood preservation.

I will be interested to learn more about rot prevention with timber.

I was hoping I would have gotten some more input from some greenhouse enthusiasts on my design ideas!