This is the follow-up to my first post. In PHPP I decided my first objective would be to analyze the thermal shell: overall building orientation, window, roof, and wall R-values, surface-to-volume ratio, window areas, window shading, etc., which all feed into a calculation of Specific Space Heat Demand. We're aiming for 4.75 kBTU/(ft2yr), the maximum SSHD to make passive house certification. I've been working on the 21st c. version of the bungalow, an urban house that is right-sized, reasonably affordable, and delightful. I wanted to know if I could also make it a Passive House.
Before I get into details, though, let me state that I haven't been through the PH Consultant training class; they haven't been offered in the Midwest since I became aware of them. The software, while complex, is fairly intuitive, at least to the extent I'm into it. At this point I'm looking mostly at space heating and not overall energy use (electrical loads haven't been considered, for instance), but it's enough to turn up some interesting insights.
I started with a few assumptions: approximately R-48 walls, R-60 roof, R-40 foundation, and triple-pane fiberglass windows and doors. Really high performance stuff by current US standards, but typical for Passive House. It's assumed that the house would have less than the maximum permissible .6 air changes per hour when pressurized to 50 Pascals (equivalent of having a 20 mph wind blowing on all sides of the house). Through earlier planning and energy analysis I arrived at a scheme with bedrooms in the lower level (floor 3' below grade), and living spaces above (about 6' above grade). It has a full-width front living room with side entry like many bungalows. Here's an overview of the volume from the northwest (remember the visual design elements will emerge from or alongside the analysis--not starting with visual preconceptions):
green garage" in the back!
Then I loaded up the south side with windows, put in generous east and west sliding doors for access to porches and yards, and ran the calculations. Here's the basic box from the west (like most Oak Park lots, ours runs E-W):
The following image shows a general outline of porch and basic overhangs (to provide shelter from summer overheating and rain/snow, and to provide spatial continuity of interior to exterior):