PHnw Building Directory

Wallingford Passive House Residence

Building Use: Detached single-family residence

Project Type: New passive house building

This new single-family house replaced a small, old building on a small neighborhood lot with a relatively limited buildable area relative to the space and functions that were needed. The house is set back from the street as far as possible, allowing for a basement garage with the steepest permissible driveway, a partially heated basement, and three stories above. Some notable features are a residential elevator, fully within the thermal envelope, roof decks, and 'moats' at the front and rear patios that allow finish grade to be flush with the interior floor, with the floor framing still bearing fully on the foundation wall.

Location:Seattle, Washington 98103
Dwelling Units:1
PH Calculation Protocol(s):PHI
PH Modeling Software(s):PHPP
PH Certification(s):PHIUS
Year Of Construction:2016

Project Size

Floor Area:3,458.4 ft2TFA321.3 m2TFA


Annual heat demand:4.24 kBtu/yr•ft2TFA13.4 kWh/yr•m2TFA
Heat load:3.30 Btu/hr•ft2TFA10.4 W/m2TFA
Primary energy demand:28.10 kBtu/yr•ft2TFA88.6 kWh/yr•m2TFA
Primary energy demand after on-site generation:21.30 kBtu/yr•ft2TFA67.2 kWh/yr•m2TFA
Airtightness:0.34 ACH50


Construction Type:wood
Floor Assembly:Basement floor (R: 34.6 h•ft2•°F/Btu):
• concrete slab
• air & vapor barrier membrane,
• 8" EPS insulation

Floor over unheated garage (R: 52.0 h•ft2•°F/Btu):
• finish flooring (tile / wood)
• plywood subfloor
• 14" TJI joists with high-density blown-in fiberglass insulation
• 5/8" drywall
Wall Assembly:Below grade (R: 39.6 hr•ft2•F/Btu):
• drywall
• 2x4 wood studs with high-density blown-in fiberglass insulation
• 6" EPS insulation
• concrete foundation wall (air barrier)

Above grade (R-38.1 h•ft2•°F/Btu):
• 5/8" drywall
• 2x8 wood studs with high-density blown-in fiberglass insulation
• ZIP sheathing OSB (air & weather barrier)
• 3" Roxul rockwool panels
• vertical furring with fiber-cement panel cladding
Roof Assembly:Lower roofs (R: 76.2 hr•ft2•°F/Btu):
• 5/8" drywall
• 14" TJI rafters with high-density blown-in fiberglass insulation
• plywood sheathing (air-barrier)
• 2x8 overframing at overhangs, 7 1/4" EPS / Roxul insulation
• 2x furring for venting cavity
• plywood
• TPO roofing membrane

Upper roof (R: 49.0 hr•ft2•°F/Btu):
• 5/8 drywall
• furring for installation cavity
• OSB air barrier
• 16" wood trusses with 14 .5" high-density blown-in fiberglass insulation
• 1.5" venting cavity
• plywood sheathing
• standing seam metal roofing
Windows:Unilux DesignLine 0.7
Entry Doors:Unilux wood entry door


Ventilation system:Zehnder ComfoAir 550
Heating/Cooling system:Mitsubishi mini-split heat pump with two ducted indoor units
Domestic hot water system:Navien 240, natural gas fired, tankless water heater
Renewables:3.3 kW roof-mounted photovoltaic system with projected generation of 3,459 kWh/yr


Passive House Consultant:Markus Barrera-Kolb
Passive House Consultant Certification:PHIUS
Architect:Whitney Architecture
Structural Engineer:Bykonen Carter Quinn
Contractor:Hammer and Hand


Additional Information:PHPP model used internal heat gain per the PHIUS protocol.

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