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Published on November 19th, 2014 | by Steve Hanley


This Is The Largest Passive House Building In The US

November 19th, 2014 by  

Originally published on Green Building Elements.


The largest Passive House structure in the US, called The Orchards At Orenco, is under construction in Hillsboro, Oregon, a suburb of Portland. The 57 unit residential building is being built by REACH Community Development, a non-profit developer dedicated to lowering overall living costs for residents. REACH believes delivering truly affordable housing places a minimal burden on the finances of low-income families by keeping utility costs as low as possible.

How did the architects make such a large building conform to Passive House standards? It wasn’t easy, and involved an extensive review of windows, doors, flooring, roof materials, and heating systems from manufacturers around the world.

What’s Inside This Passive House Building?


The exterior walls have 2×10 framing with blown-in fiberglass cavity insulation and 1.5 inch thick rigid mineral wool exterior insulation chosen for its permeability and capacity to facilitate drying to the exterior. Plywood sheathing with taped seams serves as the primary air barrier. Plastic house wrap covers the sheathing and a polyamide membrane acts as a vapor barrier on the inside.

The 3 story wood frame building sits on a slab-on-grade foundation. The ground floor slab sits on a 4-inch layer of EPS Type II insulation which also wraps around and under the perimeter and interior footings. Type IX EPS is used under the footings because of its higher load bearing capacity.

The roof is made from prefabricated wood trusses and features 12 inches of polyisocyanurate insulation. A self adhering rubberized asphalt membrane installed over the plywood roof sheathing acts as a vapor barrier and also functions as a temporary roof during construction.

With 322 high-performance windows and balcony doors going into the project, the design team researched window options extensively, looking at products manufactured in the Pacific Northwest as well as several made in Europe. The European products offered a higher level of performance at a lower estimated cost but the team did not feel comfortable specifying overseas suppliers. Ultimately, they chose Euroline windows, a company based in western Canada, because they offered the best balance of performance and cost.

The building will be served by three rooftop HVAC equipment pods, each serving 18 to 20 apartments and a portion of the common areas. Rather than designing a fully centralized system, or a decentralized system with individual HVAC units in each apartment, the pod concept offers a high degree of thermal efficiency while simplifying distribution and reducing maintenance needs. The pods will provide 90% of the heat for the building while wall-mounted electric heaters in the apartments will fulfill the remaining 10%.

Heat-recovery ventilation equipment from Loren Cook Company will be used and two high-efficiency gas boilers will provide hot water for the building.

The Orchards at Orenco building is adjacent to the Orenco station on Portland’s light rail system to facilitate low cost transportation options for the residents. Construction began in June, 2014 and completion is expected to take place in May or 2015.

Largest Passive House Building in the US

Reprinted with permission.

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About the Author

Steve writes about the interface between technology and sustainability from his home in Rhode Island. You can follow him on Google + and on Twitter.

  • Larmion

    Odd that they would refuse to use European products despite offering better performance and cost. Building materials have vast embodied energy that greatly outweigh the small emissions associated with shipping. And of course, there’s the effect of the better performance to consider in doing a life cycle analysis.

    As such, the environmentally sensible thing to do would have been to import. ‘Made locally’ is always good PR though, so I understand why they did it. Any passive building being built is worth cheering, even if it’s not perfect.

    • Lautaro Vargas

      If you just keep importing you’ll never build up a decent local supply chain.

  • Jenny Sommer

    A little small 😉
    We got a 149 apartments passive house building with 1800 window units.

    But that’s Europe..

  • Mike333

    Finally some smart houses are being built.

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