Been planning a small off-grid cabin build on my plot in the Peak District and I've gone down a proper rabbit hole trying to work out what size stove I actually need. The cabin will be roughly 20m² with 2.4m ceilings, so about 48m³ of space. Most of the calculators I've looked at spit out something like 4–5kW, but I've seen people on here swearing by 3kW units for similar sized spaces if the insulation is decent.
I'm planning 100mm of Rockwool in the walls with a vapour barrier, 150mm in the roof, and triple-glazed windows — so hopefully not too leaky. The cabin will be used mainly in autumn and winter weekends, so it'll often be stone cold when we arrive and needs to heat up fairly quickly. That's making me lean toward the 5kW end rather than going smaller, even if it means cracking a window once it's up to temperature.
Has anyone run a small stove like a Hobbit or a Charnwood Cove 1 in a well-insulated space this size? I'm also wondering whether DEFRA approval matters up there — it's a fairly rural spot so I wasn't sure if it falls under a Smoke Control Area, though I know that can change.