How we build the house is and where we build it is important. We need to use the light and heat from the sun to make the house nice and usable. we need to use natural heat and light to build, Because direct sunlight only gets into the house when we want it, we've designed the interior of the house to absorb as much of that heat as possible. The floor will be a dark wood to take in as much heat as possible and the interior walls will be painted dark to absorb as much heat as possible. The back wall will be lined with a dark slate which will absorb and hold a lot of heat. This heat can then be released when the sun isn't shining. While we want the interior to absorb as much heat as possible, we want the roof to reflect the hot summer sun so we put highly reflective corrugated metal on the roof. We want to trap as much heat as possible in the winter and keep as much heat out as possible during the summer, so we're insulating all of the walls, ceiling, and floor with 4 inches of insulation batting to give it an R-value of 13. We're also using double paned windows and doors so that there are no places for the heat to leak in or out.