Duvall Passive House

This is a new house located in Duvall, a small town in NE King County. The clients were two teachers, one of whom, a high school physics teacher, took a sabbatical to act as the general contractor for the project. The site is in a rural area on the outskirts of town.

The homeowners’ goals for the project were to:

  • build a Net-Zero Energy home (incl. an electric car – no utility or gasoline bills for the rest of time);
  • use only renewable/ sustainable/ non-toxic materials (no foam!);
  • make the project affordable;
  • build something that would last for 100+ years;
  • help revolutionize the building industry;
  • promote Passive Houses for all!

The house is two stories with an attic, and no basement. It’s traditional in style, but very cutting edge in its performance:

  • R-50 walls, R-85 roof, R-38 floor;
  • sustainable materials (no foam);
  • Vapor open (drys to inside and outside);
  • no thermal-bridging;
  • protected OSB air barrier;
  • 2/3 Insulation outside of OSB (keep OSB above dew point);
  • triple-glazed windows;
  • space heating by ductless mini-split heat pumps;
  • heat recovery ventilator for fresh air;
  • heat pump water heater;
  • 10 kW PV array.

Passive House stats:

  • Space Heating – 3.12 kBtu/s.f/yr (below req’d. limit of 4.75)
  • Primary Energy – 25.8 kBtu/s.f/yr (below req’d. limit of 38)
  • Blower door test results – 0.40 ACH at 50 Pascals!

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