We have begun again. Our new house project is starting to take shape, at least on paper. Hopefully all of the trial and error will be done before we break ground. This lot has some unusual features. For one it is flat. Since we have started building houses in Western North Carolina we have had one other flat lot. It is easy to appreciate the savings this implies. We build small homes, 950- 1500 sq ft. and being able to build slab on grade instead of a basement or crawl space not only eliminates the cost of excavation and basement or crawl space walls but also eliminates the need for stairs. Stairs not only are an involved building project that takes a fair amount of time but also take up a lot of space. An average stairwell is around 75-100 square feet. That area is not available for most uses other than storage under some portion of the stairway. Also insulating and making a slab airtight is an easier effort than either of the other options
The drawback of this lot is its orientation. It has a long north/south axis and it faces 24 degrees East of magnetic South. In our area we need to face about 7 degrees west of magnetic south in order to face true south, which means we are around 31 degrees off of true south. Being greater than 15 degrees off of true south plus that fact that this lot demands that the South orientation is the smallest dimension make it not a good candidate for passive solar design. We did look at changing the orientation by making the footprint tilted on the lot but it is a very narrow lot and with the set backs included there was not a lot of room to play with. You can see in this graphic that we have had to design the house around the lot shape to make it work as a one level lot.
The good solar news is that photovoltaic panels are not nearly so picky. They can be oriented much farther off of true south and still remain efficient. According to this graph on our 6/12 pitch roof or 26.5 degree tilt we will still be 96% efficient.
So our beginning looks like a plan for an energy efficient home with a solar photovoltaic system that will be sized to be close to the energy modeled needs of the house. One of our main decisions on paper has been to find a roof design that can accommodate the panels and is aesthetically interesting while reasonable to construct. We have not committed to a final plan yet but the variables of what the lot and the orientation are have made some our decisions clearer.