Walls and Roof

The general approach was to employ "super insulated" walls, attic and sub-slab insulation levels, combined with aggressive attention to air sealing during construction.

Subslab assembly

The slab on grade main floor is a 4" concrete slab poured over 8" of XPS insulation (R-40)

Subslab R-value 40.0
Slab edge assembly

The slab edge is supported by a 6" core ICF stem wall (R-23)

Slab edge R-value 23.0
Foundation wall assembly

The foundation is a 6" core ICF stem wall atop a continuous concrete strip footing.

Foundation wall R-value 23.0
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 43.0
Flat attic assembly

The attic is insulated with 18" of blown cellulose insulation.

Flat attic R-value 60.0

Windows and Doors

Window Assembly:

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.

Door Assembly:

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 0.21
Solar Heat Gain Coefficient 0.25
Visible Light Transmittance 0.39
Door U-Factor 0.21
Door Area 40 sq ft

Mechanical Systems

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 105 gal
Ventilation - Manufacturer & Model Balanced ERV, RenewAire EV130, 130 CFM, set to run 20 min/hr with HSO switches in bathrooms.
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

All mechanicals are within the conditioned space. Energy star lighting.


Air Changes per hour, ACH50 0.47 ACH50
Air Changes per hour, CFM50