Depending on the style of house you build, you may need to do something to maintain the temperature of your home. There are a lot of different options available that use different kinds of fuel, but I think the best options are the ones you build, and then they stop costing you money afterwards.
This is why I think this pop can solar furnace is a brilliant option. In essence, you build it, install it on a south facing wall where it will be exposed to the sun, have a vent in the wall of your home near the floor where it pulls cold air in, and natural convection will pull the air through the furnace, warm it up, and vent it back into your house through another vent in the wall.
It requires no fans, and no electricity. If you find yourself too cold or too warm, just open or close the vents. Simple, isn’t it?
I’ve seen companies that mass produce these, using pop cans, and sell them for prices around the $2500 mark. To build one yourself requires a bit of wood, some pop cans, some high temperature matte black spraypaint, and some clear PVC (I’d suggest it be UV stabilized, so it lasts longer). While I have yet to make one myself (it’s on my list), I can’t see the cost of all of this going over $100.
If you do happen to make one, please post the results in the comments below so we can see it in action.
Here is a video that shows how to make one. I’ve seen them made larger, for more heat output.
Complete written instructions can be found on this Instructables link