The general approach was to employ "super insulated" walls, attic and sub-slab insulation levels, combined with aggressive attention to air sealing during construction.
The slab on grade main floor is a 4" concrete slab poured over 8" of XPS insulation (R-40)
Slab edge assembly
The slab edge is supported by a 6" core ICF stem wall (R-23)
Slab edge R-value
Foundation wall assembly
The foundation is a 6" core ICF stem wall atop a continuous concrete strip footing.
Foundation wall R-value
Above grade wall assembly
All exterior above grade walls are 11-7/8" double stud walls with 2x4 inner and 2x6 outer studs aligned @ 16" on center. The cavities were filled with dense packed cellulose.
Above grade wall R-value
Flat attic assembly
The attic is insulated with 18" of blown cellulose insulation.
Flat attic R-value
Windows and Doors
The windows are Inline fiberglass, tilt-turn and fixed units with insulated fiberglass frames.The IGU's are tri-pane assemblies with warm edge spacers and various coatings depending on glass orientation.
Exterior doors are insulated fiberglass units. The patio door is a tilt-turn unit to match the window unit's performance and glazing specification. The entry door is an insulated fiberglass unit with dual pane 1/4 lite glass.
Average window U-factor
Solar Heat Gain Coefficient
Visible Light Transmittance
40 sq ft
Space cooling - Manufacturer & Model
Geothermal heat pump, GeoThermal - 034
Space heating - Manufacturer & Model
Geothermal heat pump, GeoThermal - 034, 36,200 BTUH, COP 3.0, EER 14.6, three 180 foot deep closed loop wells
Domestic hot water - Manufacturer & Model
Heat pump de-superheater
Domestic hot water - capacity
Ventilation - Manufacturer & Model
Balanced ERV, RenewAire EV130, 130 CFM, set to run 20 min/hr with HSO switches in bathrooms.
Lighting Manufacturer and Model
Mechanical Equipment Installation Details and Comments
All mechanicals are within the conditioned space. Energy star lighting.