Building Use: Detached single-family residence
Project Type: New passive house building
The site for this new 4-bedroom house includes steep slopes and poor bearing soil, requiring the use of pin-piles. Sweeping NW views of Puget Sound called for significant extents of glazing with very little solar gain, which in turn required assemblies with above-average R-values.
Location: | Seattle, Washington 98177 | |
Dwelling Units: | 1 | |
PH Calculation Protocol(s): | PHIUS+ | |
PH Modeling Software(s): | PHPP | |
PH Certification(s): | PHIUS | |
Year Of Construction: | 2015 | |
Project Size | ||
Floor Area: | 2,652.2 ft2TFA | 246.4 m2TFA |
2,891.2 ft2iCFA | 268.6 m2iCFA | |
Performance | ||
Heating Degree Days: | 4,342 °F•day/yr | 2,412.2 °C•day/yr |
Annual heat demand: | 4.20 kBtu/yr•ft2iCFA | 13.2 kWh/yr•m2iCFA |
Heat load: | 3.37 Btu/hr•ft2iCFA | 10.6 W/m2iCFA |
Primary energy demand: | 42.70 kBtu/yr•ft2iCFA | 134.7 kWh/yr•m2iCFA |
Primary energy demand after on-site generation: | 32.20 kBtu/yr•ft2iCFA | 101.6 kWh/yr•m2iCFA |
Airtightness: | 0.02 ft3/min•ft2 | 0.42 ACH50 |
Envelope | ||
Construction Type: | wood | |
Floor Assembly: | Slab-on-grade (R: 32.1 h•ft2•°F/Btu): • finish flooring • 4" concrete slab • poly air & vapor barrier • 8" EPS insulation Floor over cistern (R: 68.9 h•ft2•°F/Btu): • hardwood flooring • plywood subfloor • 18" wood trusses with high-density blown-in fiberglass insulation • vapor-permeable air barrier & BIB membrane • ventilation cavity (power-vented) • plywood • liquid-applied cistern liner membrane | |
Wall Assembly: | Walls below grade (R: 55.0 h•ft2•°F/Btu): • 5/8" drywall • 2x4 wood studs with high-density blown-in fiberglass insulation • 6" polyisocyanurate rigid insulation • concrete foundation wall (air barrier) Walls above grade (R: 55.1 h•ft2•°F/Btu): • 5/8" drywall • 2x4 wood studs • 3" gap • 2x6 wood studs with high-density blown-in fiberglass insulation • plywood sheathing • liquid-applied air & water barrier membrane • vertical furring & vent cavity • cladding (Boral horizontal siding, fiber cement panels) | |
Roof Assembly: | Main roof (R: 105.0 h•ft2•°F/Btu): • 5/8 drywall • 1.5" furring for installation cavity • 26" wood trusses with 20" high-density blown-in fiberglass insulation & 6" closed-cell polyurethane spray-foam • roof sheathing • standing-seam metal roofing Roof at roof-deck (R: 59.9 h•ft2•°F/Btu): • 5/8" drywall • 2x joists with 7.5" high-density blown-in fiberglass insulation & 6" closed-cell polyurethane spray-foam • plywood sheathing • roofing membrane • pedestal & wood decking system | |
Windows: | Unilux DesignLine 0.7 aluminum-clad wood (U-frame: 0.162 Btu/h.ft2.F, Unilux SuperThermo 3 glass (U-glass: 0.088 Btu/h.ft2.F) | |
Entry Doors: | Unilux all-wood | |
Systems | ||
Ventilation system: | Zehnder Novus 300 HRV | |
Heating/Cooling system: | Hydronic coil in HRV air stream, hydronic in-floor heating | |
Domestic hot water system: | Phoenix condensing natural gas water heater | |
Renewables: | 20kW roof-mounted photovoltaic system with battery backup | |
Other green building systems: | 45,000 gallon rainwater collection system with potable-water treatment for use within dwelling | |
Team | ||
Passive House Consultant: | Markus Barrera-Kolb | |
Passive House Consultant Certification: | PHIUS | |
Architect: | Whitney Architecture | |
Structural Engineer: | Bykonen Carter Quinn | |
Contractor: | Dyna Contracting | |
Comments | ||
Additional Information: | Photovoltaics: Rainshadow Solar, Inc Rainwater system: RainBank Geotechnical engineering: Geotech Consultants, Inc. |