Alternative Heating - Climate Considerations

I have really enjoyed reading through current and past heater builds and I am catching the bug.....

We have a monitor style barn. It is built on a monolithic slab. The building is 40'x48' and currently wide open. there is a second floor in the middle that is 16'x48'.

The plan is to reserve the west side 12'x48' for shop and storage. Finish out the east side 12'x48' for living space. We currently have our RV parked in the middle 16' section and live in that. After we build out the east side living space, we will turn part of the middle section (16'x36' or so) into a large open room that will be accessible, with doors, from the finished east side and have an exit to the outside. No plans for the second floor until far down the road.

At the end of the "first phase" we'll have 12'x48' finished off. Approximately 12'x12' will be the utility area and would not need to be conditioned but would need to stay above freezing so 12'x36' for living space = 432sqft first phase. I am not sure how important the info on the space is but there it is.

Lately, and in some past posts, I am reading about you all using your mass heaters in your shoulder seasons. Our winter would basically be what most of you call fall/spring so our winter is your shoulder season. Dec/Jan/Feb average 50's for the high and 30's for the low. We usually have a week in the middle that does not come out of freezing for 3-5 days and we also have some weeks creep back into 60's and 70's.

Fall and spring vary wildly. We just came out of 2 weeks in the high 70's and are looking at the 50's high/30's low coming around the corner. I have read a couple of posts where the recommendation would be to burn two smaller fires instead of one large to avoid condensation.

What do I need to know and what would be the recommendation for my climate? I am still developing my understanding and I see some of you have built single skins or double skins and some have both in different buildings on your property. I am not sure going for a larger mass would be beneficial due to the small SQFT and our climate. Any feedback is appreciated to develop my understanding to plan ahead for the build.

PS. The Ladyfolk in the house start getting cranky when we hit anything 65F and under inside, but they become very pleasant once we are back around 70F and above. I've had almost 20 years of experience with that and it is not changing.....so I keep it 70F and above, never use covers, and have a fan on me unless I am running a fever.

432 sq ft will really vary depending on insulation and airtightness-including how often you open your doors.

Hey Jackson.
It is not easy to regulate indoor temperatures during the shoulder seasons.
We often have windows open when heating with bricks.
Nothing like fresh cold air in a toasty warm room!

Well, I suggest a single skin, as a double skin takes twice as long to heat and twice as long to cool down.
Not a good fit in a moderate climate.
You might consider a hybrid design like my shop dragon, with a barrel and a brick bell.
Or if your better half does not like having a barrel in her living room, then metal plates can be used in conjunction with bricks to give quick radiant heat and longer-term storage.
J-Tubes are reliable and easy to build, but require more feeding.
First-generation batchboxes are outstanding, but require a taller bell.
Shorty Core is another good option, with a shorter riser and a smaller maximum bell size than the first-generation design.
Another choice might be a Walker riserless core.
I have one in a BBQ design that would work fine as a home heating / indoor oven heater.
They do have a smaller firebox than the others.