PHnw Building Directory

Everhart Family's Futurefit

Building Use: Detached single-family residence

Project Type: Passive house retrofit

Featured Image by Mark Peterson/Redux Retrofitting for a low carbon-emission future makes this a "futurefit" to an existing single-family residence we built in 1998. The Passive House Institute calls this an "EnerPHit." We started in 2009 and completed most envelope improvements by 2011. We are still finishing with equipment upgrades, most recently in 2017 with a Sanden environmentally-superior CO2 refrigerant heat pump water heater supplying 100% of both domestic hot water and 100% of our space heating. Already, we have cut our energy consumption by 45% from an average of 15,800 kWh/year to 8,200 kWh/year. And our space heating energy consumption by 70%. We saving approximately 7,000 kWh every year. We have disconnected 5 gas appliances and are now 100% powered by our local utility's 100% new renewable electric energy.

Location:Portland, Oregon 97215
Dwelling Units:1
PH Calculation Protocol(s):PHI
PH Modeling Software(s):PHPP
Construction Cost:$ 150,000 USD
Year Of Construction:2010

Project Size

Floor Area:1,903.0 ft2TFA176.8 m2TFA


Heating Degree Days:4,278 °F•day/yr2,376.7 °C•day/yr
Cooling Degree Days:575 °F•day/yr319.4 °C•day/yr
Annual heat demand:4.70 kBtu/yr•ft2TFA14.8 kWh/yr•m2TFA
Heat load:2 Btu/hr•ft2TFA6.3 W/m2TFA
Primary energy demand:26.31 kBtu/yr•ft2TFA83 kWh/yr•m2TFA
Primary energy demand after on-site generation:28.10 kBtu/yr•ft2TFA88.6 kWh/yr•m2TFA
Airtightness:0.75 ACH50


Construction Type:wood
Floor Assembly:hardwood: 0.25"
plywood: 1.24"
expanded polystyrene between 2X10 joists: 9.25", 23 cm
expanded polystyrene under 2X10 joists: 5", 12.7 cm
U-value = 0,101 W/(m2K)
Wall Assembly:GWB: 0.5"
Cellulose densely-packed in 2x6 stud cavity of framing; 5.5", 14 cm
Plywood structural sheathing & air barrier :0.5"
Cellulose densely-packed in Larsen Trusses: 10", 25 cm
Fiberboard: 0.5"
Air space under wood lap siding: 0.38"
U-value = 0,114 W/(m2K)
Roof Assembly:GWB: 0.5"
Fiberglas densely-packed: 5.5", 14 cm
Cellulose loosely-packed: 20", 51 cm
U-value = 0,064 W/(m2K)
Windows:Alpen High-Performance Fiberglass frame Windows Model 925
urethane foam-filled pultruded low-profile fiberglass

NFRC whole window value:
Fixed: 0.14
Casement: 0.17
Two glass panes with two low-e films between them with krypton fills

Ug-value =
Entry Doors:Innotech tilt-turn with Cardinal triple-pane low-e glazing in Trocal non-plasticized hard PVC frames

Ud-value = 1,76 W/(m2K)


Ventilation system:J.E. Storkair & ZehnderAmerica ComfoAir 350 PHI-certified HRV with ComfoTube and ZehnderAmerica and Seiho diffusers
Heating/Cooling system:2.5 kwh electric resistance coil in supply air ducts of ventilation system backing up Sanden CO2 refrigerant heat pump water heater emitting space heat via Runtal vertical radiator in main room (replaced high-efficiency (92%) condensing gas furnace)
Domestic hot water system:Sanden CO2 refrigerant heat pump water heater (replaced High-efficiency (93%) Condensing Gas within tank)
Renewables:Offsite via purchase of local utility's 100% new renewable electricity purchase plan (does not include pre-2000 hydro).
Other green building systems:1,000-gallon concrete cistern below garage stores precipitation to supply 90% of irrigation
low-flow fixtures in lavatories (0.5 gpm), showers (1.5 gpm) and kitchen (1.75 gpm)
vegetative summer shading produces grapes, raisins, and kiwis
natural linole


Passive House Consultant:Tad Everhart and Hayden Robinson
Passive House Consultant Certification:PHI
Architect:Chris Nestlerode
Structural Engineer:Mark Butler, Butler Engineering
Mechanical Engineer:Peter Reppe, Mike LeBeu, Barry Stephens and Matt Groves of ZehnderAmerica
Contractor:Garth Everhart


Additional Information:Our home is now all-electric; 90% of pre-retrofit energy was methane gas
100% of electricity is provided by local electric company's elective clean energy program requiring utility to purchase enough electrical generation from new renewable sources to supply our demand (in excess of mandatory renewable energy portfolio purchase requirements)
95+% reuse of building materials removed during refurbishment
Energy monitoring courtesy of Portland State University Green Building Research Laboratory and Washington State University Extension Energy Program

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