Orchard Street Residence, Studio-E Architecture (rendering by Hopper Design + Illustration)
A significant reason for the growth of the AIA-SWO chapter membership in the face of the years-long economic downturn has been the consistently excellent programming of our monthly chapter meetings. The May program was no exception as we heard from three experts about the history, principles, planning, design, certification, and construction processes related to implementing the Passivhaus standard.
Our presenters were:
- Jan Fillinger, AIA, LEED ap, CPHC, principal of STUDIO-E Architecture and Design Team Manager with Green Hammer, Inc.
- Win Swafford, CPHC, Project Manager and Certified Passivhaus Consultant with Ecobuilding Collaborative of Oregon
- James McDonald, Owner of Ecobuilding Collaborative of Oregon
In a nutshell, the Passivhaus standard is an objective, performance-based set of criteria focused upon energy efficiency. Literally translated as “passive building,” the Passivhaus standard originated in Germany in the early 1990s. Since then, thousands of Passivhaus-certified buildings have been constructed throughout Europe, including office buildings, schools, multi-family residential buildings, and even supermarkets. There are far fewer certified projects in the U.S. but that’s about to change as progressively more American builders and architects are embracing the standard.
The Passivhaus standard governs not just heating and cooling energy, but overall building energy use, including baseload electricity utilization and energy used for domestic hot water.
Developers of Passivhaus projects invest in insulation, super-efficient windows and doors, and an airtight shell, minimizing or eliminating the need for an active heating system. They recoup the extra costs associated with these measures by not spending heavily for boilers, furnaces, or large photovoltaic arrays. Of course, the exceptionally low energy demands also result in significant savings during the lifespan of Passivhaus buildings.
Achieving the airtightness standard of 0.6 AC/H @ 50 Pa is especially challenging. Passivhaus system design utilizes heat-recovery ventilation to capture as much as 80-95% of the heat from exhausted air while providing superior indoor air quality.
Designers use a specialized energy simulation tool to meet the performance targets in the most cost-effective manner possible. As Jan, Win, and James explained, the rigor and exactitude of the Passivhaus standard is necessary to ensure the targeted performance levels are achieved. Passihaus designers typically find that the projections of their computer models are extraordinarily accurate once the actual performance of completed buildings is measured.
The three presented a series of worldwide examples of Passivhaus-certified projects. However, their recent Orchard Street residence right here in Eugene is a most compelling argument in favor of the Passivhaus strategies.
In the Orchard Street Passive House, primary design strategies include:
- Ultra-low energy use (maximum of 4.75kBtu/sq. ft. per year for space heating)
- Super Insulation (combinations of closed cell and open cell spray foam, cellulose and rigid board insulation for R-85 Roof / R-70 Walls / R-90 Floor)
- Thermal Bridge-Free Construction (double 2×4 wall assembly modeled in THERM 5.2)
- Air Tightness
- High Performance Windows and Doors (Unilux UltraThermo triple pane, with U-0.12 and SHGC 0.5)
- High Efficiency Heat Recovery Ventilation (Zehnder ComfoAir 350, 84% efficient)
Another local Passivhaus project is part of the 54-unit low-income Stellar Apartments development designed by Bergsund Delaney Architecture and Planning(1) for the St. Vincent de Paul Society of Lane County. While a majority of the project will conform to the Earth Advantage energy standard, for comparison purposes one component will be built as a Passivhaus. If the design team’s life cycle analysis proves correct, the additional investment necessary to achieve Passivhaus certification will be worth it. The energy savings will more than compensate for the initial investment in additional materials required for the upgrade.
The Stellar Apartments, Bergsund Delaney Architecture & Planning
Jan defended the fundamental emphasis upon energy conservation demanded by the Passivhaus design approach. He pointed out that the energy to operate a conventional home far outweighs the initial embodied energy to build it. Accordingly, he argued the Passivhaus strategy is the cheapest way to build if you take life cycle costs into account.
However, Passivhaus buildings are not necessarily green in other respects. Unlike LEED-certified projects, Passivhaus projects are not required to emphasize water reduction, use of recycled building materials, or sustainable site development. Indeed, its narrow focus upon energy conservation may be its ultimate shortcoming. Michael Fifield, FAIA questioned this single-mindedness relative to site selection and size, which can have a huge impact upon a project’s true carbon footprint.(2) Likewise, I wonder if Passivhaus projects are truly exemplary once you factor in the entire suite of design considerations inherent in any project. For example, the standard does not underscore the healthful benefits of natural daylighting and attractive views, fixating instead upon sizing and arranging windows to manage solar gain and minimize heat loss.
Pursuing the Passivhaus approach certainly does not preclude embracing the full reach of LEED or the Living Building Challenge, which may be the most comprehensive and ambitious standard for sustainability in the built environment there is.
Those who attended the May AIA-SWO chapter meeting left knowing a great deal more about the Passivhaus movement than before the presentation. I suspect our profession will soon regard many of the strategies espoused by Passivhaus advocates like Jan, Win, and James as essential instruments to be carried within our increasingly sophisticated sustainable design toolkit.
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Big thanks to the May program industry sponsors, the Small Planet Workshop (hosting a Passivhaus workshop for AIA members very soon!) and SIGA, a Swiss company that develops and manufactures air tightness products for the high performance building industry. Their trainers and application advisors have industry knowledge and expertise that can assist you in the successful execution of your air tightness goals. Thanks too to the Eugene Water & Electric Board, our community sponsor. EWEB is committed to sustainability by meeting the needs of the present without compromising the ability of future generations to meet their own needs.
(1) Bergsund Delaney retained Jan Fillinger as its Passivhaus consultant for the Stellar Apartments project.
(2) After all, a certified Passivhaus that is located out of reach of sustainable modes of transportation or inefficiently occupies valuable land may be as ecologically costly as a less energy-efficient structure.