I have commandeered a stack of new walk-in freezer panels with enough walls and ceilings to make a 33x62x10 building. For those not familiar, these are similar to SIP panels and just lock together via tongue and grooves with camlocks. I worked for a company in high school that dealt these coolers and freezers to grocery stores, liquor stores, etc and I was on the install crew so I'm well versed on that part, however the fine print such as heat loss is not something the MFG provides, although they spec and provide the cooling equipment with the box. The only info I've gotten from them is that the panels are all R44 closed cell foam. These particular panels are structured entirely of foam, there is zero wood in them whatsoever- only the foam and 24ga steel sheathing on each side, so in order to support the roof trusses I'm leaning towards hand framing a 2x4 interior wall around the perimeter which I'd fill with R13 glass. No thermal bridge and R57 walls ought to leave me with a fairly easy to heat building, save for the overhead doors and windows.
I would love for this to be a radiant slab application, but I'm afraid the floor will never be "warm" anyway so I am open to suggestions on that part, maybe a low mass like radiant ceiling? Manual J does not give an option for anywhere near this R value, nor can I figure out how to work an overhead garage door into the equation. I can get R18.4 overheads readily, so that is the plan for right now. This will be mostly a heated storage garage for vehicles and ATV/snowmobile/lawn tractor/skidsteer type items so I can have my shop back in these lovely MN winters. I have a wood boiler in place that currently heats my house and shop via insulated underground lines, and I will tie this new building in as well. The boiler is getting swapped this fall anyway and at that point I would like to make a couple changes there as well, with a plate exchanger within the boiler cabinet and constant circulation only through it and the loads circulating only on call for heat to minimize ground loss. Despite having buried top dollar pipe, there is still a ~150,000 BTU a day ground loss with constant circulation 350 feet round trip to my house so it does add up. Not that I would really need to have a heat loss for the building, as the wood boiler doesn't care, but I would like to know what I have and especially if I go with something like a radiant ceiling it will become more of a necessity. Tried SlantFin as well and can't even come close. Regardless of heating method, I'll probably just have a line voltage stat to spin a 15-58 and pull glycol through a mixing valve from the plate and run it through the system. Yes, it'll be cold for a minute after sitting idle in the underground lines but I don't care. Please excuse my rambling, I over-explain things to avoid answering a million questions later on. Anybody have a good way to calculate the heat loss? TIA!