Synopsis: The 2018 Best Energy-Smart Home Award goes to Eric Woodhouse for a contemporary split-level spec house that achieved close to Passive House levels of airtightness. Rigid insulation was installed over the slab, and then 7-1/4-in.-deep double-stud walls were dense-packed with cellulose insulation. Open-web trusses were used for the second floor, and I-joists for the roof framing. Zip System sheathing is the primary air and water barrier on the walls and roof, and the roof system is unvented with dense-pack cellulose in the rafter cavities in addition to foam installed above the sheathing. The house is heated with a homebrew version of hydronic radiant tubing installed under the finished flooring, controlled by a Nest thermostat. The walls have conventional stucco over a ventilated rainscreen assembly, and there is a PV system on the roof sized to produce more energy than the building needs. The article includes in-depth drawings of the roof, wall, and slab details.

The original house on this site was built in 1946, and by the time I bought it in 2012, the house had become pretty run down. I’d had my eye on the site for several years, primarily because of the location. It’s within easy walking distance of schools, shopping, and restaurants, and it’s surrounded by public open space. Most of the other houses in the neighborhood were newer and in much better condition. It seemed ripe for a spec house.

Since this is a spec home, we attempted to design a house that would be flexible enough to meet the needs of a variety of potential owners, but we were also faced with some challenges. The 50-ft.-wide lot with required 6-ft. setbacks on each side definitely constrained what we were able to build, as did the limitation of being able to build to…