Question

Are the same building materials used in Passive House construction as in traditional home construction?

Asked by Eric Simms
Seattle, WA

I'm interested in the Passive House design standards; the claim of up to 90% savings in my heating bill is very motivational. I'll be starting the design and build of my home within the next year and and wonder how exotic the materials are to do a Passive House.

Answer

Tessa Smith

Answered by Tessa Smith

Olympia, WA

The Artisans Group

May 16, 2010

Emphatically yes! That is the beauty of the approach; it is open to developing technologies, but entirely achievable with commonplace American building materials.

The simple answer is we just end up using a bit more of those ordinary materials such as insulation and framing. It is easy to think that a Passive House, with its 90% reduction in energy use, would employ outlandish technology, hovering tools and beams of alien light, but that is not the case.

Construction is similar in process and even material choice, the only variance being the extra care and testing taken for air-tightness requirements and longevity. The wall could still very well be composed of studs, insulation, sheathing and drywall. How they are arranged in the assembly is where you will see the biggest difference.

For example, you might have a double-stud wall to eliminate thermal bridging, deeper and filled with more insulation. The sheathing would likely be on the interior (for air-tightness and vapor barrier, refer to my previous article about vapor barrier location) under the drywall. Then an open-diffusion fiber board would occur on the exterior of the wall in conjunction with a rainscreen siding application. Voila! The 200-year house is born, no alien technology required.

The same kind of thinking gets applied to other assemblies and components of a Passive House: floors, roofs, etc. Two of the places you will see a bigger difference in “typical” construction materials are:

  1. the mechanical system, Heat or Energy Recovery Ventilators being the choice of the day for fresh-air delivery and in some cases even space-conditioning delivery.
  2. specific high-performance Passive windows. It still looks like a typical window, mind you; it is just substantially better performing.

The energy performance is the standard. How you get there is up to you, your budget, your location, your network and expertise -- it is the advantage of a holistic approach. The Germans have a larger Passive House market than we do, and subsequently they have many construction means and methods being developed specifically to reduce cost and speed up construction. Once our American market is flooded with Passive Houses we will see those same kind of leaps and strides in progress.

One of my Passive House clients and I were chatting the other day, and being intelligent, informed and excited about his own Passive House in the design process, he stated, “You can drive a hybrid, or you can just not drive at all!” In other words, you can toss technology at the “problem” or you can eliminate the problem. That is the elegant solution of Passive House design.

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