This one car will displace 15 barrels of oil per year in actual use from efficiency. This house is on a north facing slope in a Pacific Northwest forest. Just figure out how much fossil fuel has to go into the generator to get that 1,200 watts. You could use a tip-up tower just like they use for wind mills, to get over the trees. The losses should be about equal though windows, through walls, and air exchanges.
Most heat loss is through windows.
The least heat loss would be through the walls and roof and foundation if you have eliminated thermal bridging. I found the summer temperature was very easy to control by opening windows in the evening or morning, though not usually necessary. The house was owner built and low cost. If you matched that on the roof and have about r20 in your foundation, that's about as high a r value that is practical unless you are in Alaska, etc. Last, I snipped your discussion of district heating which was very good.