It just occurred to me that my own house is almost net zero. We use no fossil fuels. We heat with wood grown and havested on our own property (by me - gas in the chain saw) and use a modern high eficiency wood stove. we use a few hundered dollars of additional electricity for the radiant ceiling panels, mostly when we are away for a few days in the winter. There is no other heat system and we don't need one. I have about r40 fiberglass in the attic and our walls are 2 x 4 with (not very intact) fiberglass batts. windows are single glazed with aluminum storms and an additional layer of plain glass by me. no low e. In short,the house is insulated to an average level and does not meet code for new construction. We heat our hot water and cook with electricity and use 500 to 700 kilowatt hours per month. With the addition of photovoltaic panels, we could achieve net zero!