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.’
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.
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 (4.75kbtu/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.
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.
Portland-Based Root Design Build is presently working on a passivhaus in Hood River, Oregon.
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 Ecohome by Greentomato follows a Victorian remodel trying to meet PH standards in the West London.
- Rob Hawthorne’s infill development, Corehaus, in PDX.
- The nauhaus under construction in Asheville, North Carolina.
- The Oesterreich Haus in Whistler, B.C. – built with cross laminated timber.
- CLAM’s BLUE2, passivhaus and affordable housing.
- Stone’s Throw Design Inc’s Rosedale House in Toronto.
- Zero Energy Design’s Passive House New England.
- Passivhaus Institut’s project database
- PHIUS – PHI United States
- Presentations from 2009 PH conference in Urbana
- CEPHEUS (Cost Efficient Passive Houses as European Standards) – final report
- IG Passivhaus (AT), which has a database of PH and near PH projects in Austria.
- Passive House California resources page.