PHnw Building Directory

Blue Ridge Passive House Residence

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 ft2TFA246.4 m2TFA
 2,891.2 ft2iCFA268.6 m2iCFA


Heating Degree Days:4,342 °F•day/yr2,412.2 °C•day/yr
Annual heat demand:4.20 kBtu/yr•ft2iCFA13.2 kWh/yr•m2iCFA
Heat load:3.37 Btu/hr•ft2iCFA10.6 W/m2iCFA
Primary energy demand:42.70 kBtu/yr•ft2iCFA134.7 kWh/yr•m2iCFA
Primary energy demand after on-site generation:32.20 kBtu/yr•ft2iCFA101.6 kWh/yr•m2iCFA
Airtightness:0.02 ft3/min•ft20.42 ACH50


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


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


Passive House Consultant:Markus Barrera-Kolb
Passive House Consultant Certification:PHIUS
Architect:Whitney Architecture
Structural Engineer:Bykonen Carter Quinn
Contractor:Dyna Contracting


Additional Information:Photovoltaics: Rainshadow Solar, Inc
Rainwater system: RainBank
Geotechnical engineering: Geotech Consultants, Inc.

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