I'm building an ice house. I buy tree seedlings for resale and my own use. Stored in shade, seedlings can be kept for about 3 weeks. I hope to extend this to 10 weeks using a cold room.
Version 1 is an insulated 10x10 shed (R12 fiberglass in walls and ceiling) In this shed, I'm putting 10 200 liter barrels of water (2/3 full) to freeze. Barrels are on blocks so the bottom will freeze faster. Water surface is covered with 3" of Styrofoam peanuts to slow down the top freezing I'm hoping this will prevent or reduce bulging, and that expansion will take place in the center of the top, much like an ice cube in the fridge.
The tops of barrels are covered in 2" styrofoam plank. Boxes of seedlings are top of the styrofoam. A thermostat will run a fan to maintain the temperature at the seedlings between 0 and 2 C (32 to 35 F)