Allen Smithee

re: I think if you're going to do some solar, go all the way. 6 large panels-coverter-maybe some batteries and you can run 1 or 2 of those small 6x10 electric room  heaters ($12 bucks walmart), maybe a dish heater, however with fans is probably better depending on the size of your green house. It would also allow you to run some fans in summer. If you want to just test the "thermal mass" heating concept: take a heat rock, you know the ones, for pet lizards, put it in a 10 gallon fish tank, and put it in your 40o to 50o garage with a couple of thermometers. (suction cuppys) 1 inside and 1 on the outside. I think you'll see just how inefficient "thermal mass" is. The rocket stove, and the "conductive" metal is what actually heats the air in the space. And that's what you want to do: heat the air. Not put the energy from the fire or energy source in to non-conductive materials like cob, concrete, rock, etc, which only have about a 1 to 1.5 efficiency. (ie. it takes 3 hours to heat up, then cools down in 3 hours) Not to mention those non-conductive materials "radiate" jack and shiznit when jack left town. lol.. Anyways, Good Luck to ya!

I think when it comes to winter growing, you really need to look at the practicality of it, especially on the small home scale. This is how I look at it: What kind of harvest, if any, can I really get without running a 5' run of insulated ducting from my house heater to a greenhouse? What's the cost effectiveness of heating, in essence, 1 room that constantly loses heat, but only gets some warm air when the thermostat room activates the heater? And I'm still not gonna have a jungle out there. lol You're probably talking about a room, that if I'm lucky can keep at 45o-55o degrees at best during winter. What grows well at that temp?  And that's a conventional solution, which I would guesstamate would cost me and extra $30 bucks a month on the heating bill. I've been working with "thermal mass" experiments to see if I could produce enough heat to actually grow a sustainable crop in -5 to 20 degree F, and to get right to the point: "Thermal Mass" heating is the lowest common denominator for trying to heat ANYTHING! It can keep a room above freezing, but heating essentially a rock is a waste of your energy source, and yes this includes your fires energy. It's just completely inefficient. Water barrels take up valuable space in small green houses, are a pain to move when full, for what they do. Painting surfaces black is great for winter, but what about summer when that space is approaching 160o degrees? LOL.. Also indoor growing and the bugs... There is also the consideration of fresh air being introduced. I think in essence my conclusion is that there's no way in hell you're going to in grow winter and summer crops without: 1) the building being specifically designed for it (efficiency) using modern materials, and supplemented with some permie tech to offset cost. And yeah, aint talking about no Harbor Freight green house... lol I'm currently working on a way to increase a fire energy source specifically for green houses, but I haven't seen anyone grow anything but scrub brush in winter without pro-pane heater heat. The questions you're asking, people have been racking their brains over for a long while. My honest belief is that a very small fire can be used, however that source of energy needs to be magnified by 10. One can spend a lot of money on perm tech, but there are some serious limitations cost verses what you can actually grow at home on a small scale I believe. Just an opinion.