Passivhaus: an aggregate primer

The brainchild of Wolfgang Feist in Darmstadt (DE), Passivhaus is an ultra-low energy standard. The Passivhaus Institut defines it as, ‘a building, for which thermal comfort can be achieved solely by postheating or postcooling of the fresh air mass, which is required to fulfill sufficient indoor air quality conditions – without a need for recirculated air.’

photo: passivhaus institut

Over the last 18 months, Passivhaus has been covered pretty thoroughly in several publications (NYT) and blogs (treehugger, etc), including a solid background at greenbuildingadvisor. We even caught an engineer proposing PH as an alternate to LEED certification – a win-win situation in our eyes. We’ve been following PH for a few years, and are rather excited to see this post-LEED standard reach critical mass.

Passivhaus is not only a proven route towards net zero, but a green building standard that routinely outperforms LEED where it counts: energy efficiency. And while having bike racks, ZEV parking, low/zero-VOC paints and recycled construction waste are good things – to us, that is really the starting point. We’re big proponents of LEED moving to a performance-based system to earn the coveted ‘platinum’ designation. Until then, we’ll be lauding minergie, passivhaus and the kybernetische prinzip til the cows come home.

passivhaus compared to other standards

Requirements

Unlike LEED, where you aren’t required to meet every stringent standard to be certified (you can pick and choose, and most select cheaper, non-energy related points), the passivhaus standard is either achieved, or it isn’t. There is no middle ground, there is no passivhaus silver. The following requirements must be met to be certified a passivhaus:

  • Annual Heating: 15 kWh/m²/year (4.7kbtu/ft²/year) or less
  • Primary Energy: 120 kWh/m²/year (38kbtu/ft²/year) or less (heating, lighting, hot water and electrical usage).
  • Airtightness: achieve a blower door test of 0.6ACH (Air Changes/Hour) @ 50Pa. An excellent strategy to ensure airtightness is to build with cross-laminated timber.

In order to meet these standards, there are a number of other steps that are recommended:

  • A compact building form, sited to maximize winter solar gains.
  • Super-insulated building elements of U ≤0.15 W/(m²k), or R-38. This can result in walls being 12″ thick or more. Having worked on 24″ thick rammed walls, we don’t feel this is necessarily a disadvantage. However, thick walls on a small site mean less livable area for occupants.
  • Elimination of thermal bridging.
  • Highly efficient windows with a U ≤0.8 W/(m²k), or R-7.1. Typically, this involves triple-glazed windows with low-e coatings and insulated frame.
  • Heat Recovery Ventilator (HRV) with an efficiency of 75% or greater.
  • PH makes use of process heat (similar to das kybernetische prinzip) from appliances, lighting and yes, even humans.

Despite the designation, passivhaus standards are not only for houses, but are applicable for schools, office buildings and even fire stations. Gernot Vallentin’s passivhaus montessori (PDF, english) in Aufkirchen (DE) is a recent and innovative example.

passivhaus in satteins (AT) by walter unterrainer

Northwest PH projects:

There are presently a number of projects in various phases here in the Northwest. The following represent some of the more interesting ones.  

The first permitted PH project in Seattle is by local builder Dan Whitmore. Dan’s project uses modified Larsen Trusses and progress can be followed here.  

Olson Kundig has a PH in planning for Calgary that appears to be somewhat promising.

Heliotrope has a PH project underway in Green Lake that aspires not only to meet PH standards, but looks really friggin gorgeous as well. Respect!

PH Project Blogs:
  • Fellow VT alum and NYC architect Jeremy Shannon of Prospect Architecture remodels a PH brownstone in Brooklyn.
  • Fourthickwalls follows construction of a non-modern PH project in Chicago.
  • Postgreen’s passive project has some really wonderful posts on issues that came up during construction process.
  • Somehow flying under our radar, Loadingdock5 has 2 PH projects underway in NYC.
  • TE Studio’s Passive House in the Woods follows construction of a PH house utilizing SIPS in Wisconsin.
  • The cohome by Greentomato follows a Victorian remodel trying to meet PH standards in the West London.
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  • martin d

    i believe the passive house in the woods is “constructed with 11-in. insulated concrete forms and an exterior-insulation and finish system that brought the overall R value of the walls to 70″

  • http://www.bruteforcecollaborative.com mike eliason

    Martin,

    You are correct and I knew that, might have been thinking of another project. Thanks for pointing that out.

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