Design elements for Greenhouses?

Hi. I am researching to design a couple small greenhouses for my property. One of them will mainly be used for starting seeds and to create a heated space for my chickens during winter, the other a sunken greenhouse for year round more permanent plants.  So far I'm looking at lots of ideas on design elements but like others inputs especially if I've missed something that might be useful as far as uses, utility, heating/cooling, water harvesting, etc. I have a HUGE pile of arborist wood chips (FINALLY the wood chip god has favored me and I have so many wood chips I can literally build a house inside the pile. NO JOKE!)

I plan to do a jean pain style heating system with a water tank inside a greenhouse and the pile outside butted up to my chickens coop. So it can serve dual purpose of heating the greenhouse through hoses of water and providing a heated space for my chickens. I'm toying with the idea of cover that area to hold the heat a little more, kind of similar to what edible acres does with their heated high tunnel for their chickens. I think I will also build a bin along the greenhouses back northern wall and create a long compost bed their for heating and use that to put my seed trays on for germination, as well as a grate on top of my water tank connected to the hoses for starting seeds on top.

For the permanent greenhouse I plan to sink it with a French drain (I live in Tennessee and worried about possible flooding of it. I don't think I would need geo thermal in it because it's sunk? I like the design element of the trench that Paul uses in his greenhouse model. I didn't know if I should plan to put a rocket mass heater in this one for the winter? Was thinking the mass should run on the north wall and could be best used for seed starting like the compost wall in the other one.

So so far I've looked into sunken greenhouses, compost heating systems, some geo thermal... not sure how deep in TN though, I don't think our frost line is much lower then 2.5 feet? And using a heated water tank to heat the greenhouse and or also running heated water tubes in my in ground beds. As well as rocket mass heaters.

I would like to implement systems that don't require lots of input and are fairly simple and low cost to run and not a terrible amount of work and maintenance. Have I overlooked anything? Am I missing anything cool I might be able to utilize?

Thanks in advance for any and all help and assistance.

I have windows to up cycle and clear tin for my permanent greenhouse and like the idea of maybe using cob?  The seed starting GH, I am planning to construct using self harvested cedar or other poles and pallet wrap on individual panels and then screwed together and attached to in ground set posts. How do I calculate the best angle for my roof to capture and reflect the most sun? My site unfortunately isn't the best so I need to reflect fr where it will be sitting.

Hi Evelynn, welcome to Permies!

I think I can visualise what you mean with your seed starting greenhouse - a diagram may help however. I appreciate that the water enables you to move heat about, but it does complicate the system somewhat. Can you just put jean pain heap inside the greenhouse to use the heat do you think? That would eliminate a lot of complexity of plumbing. The chicken house then would share a wall with the greenhouse to share the heat with the chickens.