By Jay Fox

When Parkview at Terwilliger Plaza opened in April 2024 it claimed several titles. The 11-story, concrete building consists of an entire city block located just south of the urban core of Portland, Oregon, and is the largest Phius-certified senior living facility in the United States. At 370,000 gross square feet, Parkview is also the largest Phius building on the West Coast of the U.S.

As much as these superlatives are Parkview’s alone, the building should not be considered in isolation, as it is the most recent addition to Terwilliger Plaza Retirement Community. Created in 1962, the organization is a nonprofit 501(c)(3) organization owned by residents, and it is governed by a board of directors with a resident member majority. For years, the Terwilliger Plaza campus had consisted of three residences spread across three buildings (The Tower, The Heights, and The Terrace and Metcalf). Parkview expands the footprint of the campus and adds 127 units of high-end housing to Terwilliger Plaza, bringing the total number of apartments to approximately 550.

“We Just Want Something That Works”

Even before the Parkview property was developed, the block where it now stands had been included within a master plan that Terwilliger and LRS Architects created many years ago. Initially, the plan had included just a four- or five-story building on the site, which had previously housed a strip mall that contained a dynamite sushi restaurant, but leadership at Terwilliger recognized the need for a larger building with bigger and more upscale units as they began to seriously explore their market and how they would finance the development of the  property.

Terwilliger once again engaged LRS Architects, who assigned Architect Peter Houseknecht (now retired) to the project. Houseknecht says he found a willing partner when its members asked their board to inquire into the use of sustainable design, though the board had not set clear parameters for what it meant by “sustainability” and many members had little familiarity with high-performance construction. Luckily, board members were eager to learn, and Houseknecht walked them through the differences between several different building standards, including LEED, Earth Advantage, and Passive House. Some members of the board even visited a job site where Walsh Construction (which would eventually assume the role of general contractor for Parkview) was working on a Passive House project. Houseknecht adds that PAE worked as engineers on the same project and later shared measured energy use data with the Terwilliger board members showing the building was performing better than projected. The proof of performance was key to instilling the board with the comfort, confidence, and commitment to pursue Passive House.

While the board eventually decided to build using passive principles, they were still lukewarm on the idea of certification even after several years. They told Houseknecht, “‘We just want something that works.’” They preferred performance over any kind of performative greenwashing, and “do as much as we can afford” became the mantra. As Houseknecht reasoned, this was understandable; the residents would still achieve some sustainability goals and be able to recognize the benefits even if they did not meet all the criteria for certification. They would also live on a campus with a building they could be proud of.

However, as the team got closer to breaking ground over the more than three years of preconstruction, they realized that the building was very likely going to meet all the requirements for Phius certification. Towards the end of 2019 or early 2020, the board decided to go through with it, as they believed certifying would be beneficial from a marketing standpoint and that they would be able to obtain green bond financing at a favorable interest rate.

Both have turned out to be true, especially with respect to occupancy rates, the board reported to Houseknecht. “They’re doing better than they expected,” he says. Meanwhile, the financial savings from green bonds saved them a large amount of the construction cost premiums to meet Passive House standards, thereby substantially reducing their payback period.

Creating Connection

Houseknecht and the board were never fully confident that they would meet Phius standards prior to construction. While there is always some concern regarding the cost premiums associated with high-performance building, there was an unusually severe escalation in construction costs throughout the entire design period. However, key project team members were selected during the design development phase to optimize their chances, and those who are familiar with the Passive House community in the Pacific Northwest will quickly recognize several all-stars from the Parkview lineup, including engineering firm PAE, which served as Passive House consultants and mechanical, electrical, and plumbing engineers; envelope consultant and Passive House verifier RDH Building Science; and general contractor Walsh Construction.

Parkview’s design is U-shaped with a central courtyard, with the opening facing west towards SW 6^th Avenue and the other buildings that make up Terwilliger Plaza. This orientation was decided upon because it helps to connect Parkview to the existing campus and maximizes the views of the city skyline, the Terwilliger Hills, as well as some of the tallest peaks of the Cascade Range, including Mount Hood and Mount St. Helens.

Parkview is connected to The Terrace (and the rest of the campus) via an aerial bridge that sits outside of the Passive House envelope. The bridge has its own air handling system and its own dedicated mechanicals that extends into the lobby area of Parkview, which made testing and certifying the rest of the building far easier. It is a double-pane curtain wall construction with a green roof that consists of an inverted roof membrane assembly and extruded polystyrene (XPS) insulation. The decision to reduce the amount of thermal insulation and glazing relative to the rest of the building was in response to energy modeling indicating a need to allow more heat loss from the bridge structure to avoid overheating.

Creating a variety of public spaces (both indoor and outdoor) was a top priority. In addition to encouraging intermingling and building community, this was also done because Terwilliger is home to dozens of different groups and committees that all need separate spaces where they can meet. This includes everything from small conference rooms to a sizeable auditorium that is housed on the same floor as the aerial bridge.

Then again, the campus is not meant to be isolated from the rest of the city. Residents can also easily leave and walk to parks, restaurants and cafes, the campus of Portland State University, and downtown Portland. They can also easily access public transportation to travel to other parts of the city.

Building Out the Passive Envelope

Throughout the preliminary stages of design, performance often took a backseat to other priorities, such as optimizing views, providing extra-large balconies, or creating prosocial environments. “It’s not like we sat down and said, ‘Let’s design a Passive House,” Houseknecht says. “It was more like: The concept based on a host of other unrelated parameters prior to sustainable design discussions, and now our goal is to maximize sustainability. How are we going to get to Passive House?”

Of course, by the time of the official groundbreaking, in summer 2021, the team was fully committed to constructing a Passive House building.

Discounting the cladding system, the U-value of the wall assembly is 0.047. To further improve performance, the wall assembly includes a channel for ventilation that sits directly behind the cladding system. To provide additional shade, thermally isolated metal screens have also been installed around south-, east-, and west-facing windows using the existing cladding support system. Some shade is also provided by balconies. The terrace doors and windows are manufactured by Innotech Windows + Doors. With an airtightness of 0.01 cfm/ft² (doors and operable windows) and 0.00 cfm/ft² (fixed windows), and an average U-value of less than 0.19 Btu/hr·ft²·°F, Young is confident the specified fenestration would successfully support the team’s Passive House targets.

The roof assembly is a green roof on an inverted roof membrane assembly that relies on XPS insulation (R-60 minimum) sandwiched between drainage mats. Beneath the more inboard drainage mat is hot fluid applied waterproofing by American Hydrotech that is applied to the concrete slab. To encourage proper drainage, the slab is sloped. The assembly beneath the courtyard, which sits atop the unconditioned parking garage, relies on a similar green roof assembly, but there is no insulation except along the perimeter of the podium.

RDH Associate and Senior Consultant Bill Collingwood points out that the wall assemblies, including the sunshades, were built out as stand-alone mockups to ensure the detailing translated to the real-world. While the drawings are nice and clean, actually installing everything in the field reveals how everything works together and how best to sequence the actual assembly. Even when working with a GC as experienced as Walsh Construction, mockups are vital for establishing clear reference points with respect to how assemblies should fit together.

According to Walsh Construction Quality Manager Jake LaManna, an equally critical role that needs to be filled during construction is a daily observer and coach for the enclosure. According to LaManna, “They coach the less sophisticated subs, track the work for completeness of the air barrier, witness ancillary trades that impact the air barrier later in construction and may not appreciate the impact that their work has on building performance, and also prioritize the rest of the enclosure activities.” The ‘coach’ on this particular project was Doug Dinsdale, a decade’s veteran of Walsh’s quality program.

LaManna also says that this position was particularly important while working on one of the trickier portions of the building: the portion of the Passive House envelope that sits between the inhabited spaces and the parking garage. The garage is outside of the envelope and makes up one full story and a portion of another two floors. The property contains a notable slope, and the portion of the stories that sit below grade are part of the garage, while the portions that sit above-grade are apartments.

LaManna says that fire sealing is particularly important at this junction because there are numerous penetrations (e.g., plumbing, electrical) going from the occupied space into the service space within the garage. It can be really easy to shift blame and to fail to seal up certain penetrations when there are a lot of overlapping responsibilities. Consequently, a lesson learned from Parkview would be to consider a single subcontractor responsible for all fire sealing on the project, rather than each distinct subcontractor (mechanical, drywall, plumbing, electrical, etc.) handling their own fire-stopping, -sealing, and -safing responsibilities.

LaManna also stresses that the enemy of all buildings is water and that below grade waterproofing can’t be subsumed by the effort to create an airtight enclosure. “You still have to do the basic things well,” he says.

Mitigating Heat Loads

Many highly efficient buildings in the Pacific Northwest have historically been able to remain comfortable throughout the summer with minimal air conditioning or, when close to the ocean, with no air conditioning at all. In fact, buildings in Oregon are not required to provide air conditioning because of the state’s historically temperate climate.

However, this paradigm is changing, and the board was adamant that active cooling be included in Parkview. Some of the hottest years on record have occurred recently, with eleven of Portland’s hottest annual averages occurring since 2000. Seniors are more sensitive to extreme temperatures and are at an increased risk of heat-related illnesses, so it was a sensible thing to propose.

The centralized heating and cooling systems consist of heat pumps with fan coil units in the individual units and public spaces. The ventilation system is comprised of heat exchangers on the roof that deliver fresh air through the fan coil unit. The central air handling units are from York, the air-to-air energy recovery units are from Ventacity, and the decentralized units and fan coil units are from LG. As the building is all-electric (with the exception of a few outdoor gas grills and fireplaces), none of the appliances run on gas, including the electric heat pump domestic hot water heaters. Meanwhile, a solar system has been installed on two existing buildings within the Terwilliger Plaza campus and provides 30% of the building’s power. Houseknecht notes that the array also solved an aesthetic problem in one instance because the flat roof of one of the existing buildings is now more attractive.

Given the temperate climate of the Pacific Northwest and the number of occupants in the building, Houseknecht says that heat loads were triple the cooling loads, and the team had to consider some novel ways of allowing the controlled transfer of heat out of the building without sacrificing airtightness.

While the team had considered using prefabricated balconies that could be clipped onto the building exterior to minimize thermal bridging, all available options were beyond the project budget. The balconies as they were designed simply proved too big for prefabrication. Casting in manufactured thermal break systems was not feasible. Similarly, including XPS between the reinforcing was also not feasible because there was too much post-tensioning cable coming through the balcony.

However, what appeared to be a challenge actually turned out to be a solution, as the temperate climate of Portland meant that the concrete balconies could actually be used to expel excess heat if they were included within the floor plate.

While the solution worked in Portland, Collingwood notes that this detail might not meet Phius requirements in colder climates.

The detail for the balcony door was also a little tricky, as modeling indicated that there would be a cold spot along the concrete directly behind door, and that it could pose a risk of condensation. To resolve the issue, they created a 1.5-inch cut in the slab that extends 6 inches and contains a thermal bearing pad set in epoxy. Luckily, the flooring is not finished concrete, so the occupants have no idea the pad is there. All they know is that their floor isn’t cold.

Lessons Learned

Parkview was officially awarded design certification in April 2025. For Houseknecht, this was proof that patience and perseverance are two of the most necessary virtues when pursuing Passive House certification. Of course, there are also more technical matters that need to be addressed.

Prior to construction, Houseknecht recommends that all major stakeholders have regular meetings together to go over the design of the project and to align themselves not only with the principles of Passive House construction, but also the specific assemblies, details, and material selections that can get a project to Passive House. This is to develop a thorough and in-depth understanding, buy-in, and commitment by the entire team, as execution is equally important to the design to achieve real-world, high-performance building.

LaManna shares the belief that everyone needs to be on the same page and refers back to the process of detail review. It took place over an approximately ten-week period during the early days of the COVID-19 pandemic as people were just learning about a relatively new app called Zoom. For LaManna, sharing the same vocabulary when discussing the nuances of enclosure detailing is vital.

LaManna, Young, and Collingwood all stress the importance of pretesting the air barrier on a portion of the project to ensure that there are no blind spots in the design. This means no one has to spend days hunting down different iterations of the same gap in the air barrier with a thermal camera and a smoke stick. LaManna also reiterates that fire sealing, specifically on concrete frame construction elevated above a parking structure, is of critical importance and should be the responsibility of one designated sub in every assembly. Distributing it across multiple subs can lead to gaps in communication and gaps in the scope.

For Young, one of the most important elements of predesign is ensuring that there is a continuous air barrier. This will allow you to conceptualize where junctions will need to be sealed, what materials you’ll need to use to achieve this goal, and where each penetration will occur.  ”The key is to be able to draw the perimeter of the air barrier without taking your pen off the page when you do it,” he says. “If you take your pen off the paper, you have a hole in your air barrier.”