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A wrap date is just around the corner for the PAE Living Building, which is expected to eventually be certified as the world’s largest commercial living building.

Lead team members from PAE Engineers, Edlen & Co., ZGF Architects and Walsh Construction gathered Thursday during the 91视频’s latest Builder Breakfast event to discuss lessons learned during the project in downtown Portland.

That team sought to construct a building that would meet perhaps the world’s most stringent sustainability metrics. The project spent 28 months in preconstruction to ensure that all systems would pencil out, Walsh Construction chief estimator Ed Sloop said. Now the structure is anticipated to be self-sufficient in terms of energy use, water use, waste treatment and more.

But to achieve the International Living Future Institute‘s Living Building Challenge, the building will need to demonstrate that all sustainability goals were met. Certification is given only after a full year of occupancy and systems testing.

The project team has received the green light to turn on all of the building’s systems, PAE Engineers principal Marc Brune said. The one-year audit is predicted to begin in May or June 2022, once the building is at 80 percent occupancy.

All metrics associated with building occupancy, such as energy use and water use, will be measured during that year. Then other systems will be audited separately.

Design/mechanical engineering + plumbing

The first challenge for the project team was solar energy, Brune said. Downtown Portland has a protected grid network, and if the five-story, 58,000-square-foot building were to send excess energy to the grid, a 12-block radius blackout could result.

The team engaged with Portland General Electric, Brune said, to find an appropriate amount of energy the building could feed back to the grid. That ended up being 50 kilowatts, so a battery in the building will store any surplus.

The next challenge was the building’s size 鈥� specifically its roof. The urban site meant the building’s space was up rather than out, ZGF Architects principal Justin Brooks said, so there was less space on the roof for solar panels. Also, the Skidmore/Old Town Historic District cannot accommodate reflective surfaces (i.e., solar panels can’t be visible from the street).

As a result, the project team donated 215 kilowatts of solar panels to Renaissance Commons, an affordable housing building within the same utility district, to benefit both buildings. Carly Harrison, development manager at Edlen & Co., said it’s about $20,000 worth of power every year.

Financial

Project financing came via a developer-driven model with investors. That means the building needs to not only perform in terms of sustainability but also economics, Brooks said. To the project’s team knowledge, this type of financial model hasn’t been done yet for a potential living building 鈥� or at least at such a scale.

The financial model was intentionally designed to make this type of project more replicable, Harrison said. Typically, living building projects are subsidized by grants 鈥� a model much more difficult to repeat.

鈥淭he biggest challenge was really how to thread the needle of the cost and the rent needed to make it pencil,鈥� Harrison said.

Team members did not mention the project’s cost on Thursday; however, Portland Bureau of Development Services permit information in April 2020 placed a $20.5 million value on the building’s structure.

Much of the project cost is associated with the special systems, especially for plumbing, electrical and solar. Also, the water treatment and waste treatment composters require a large mechanical room, reducing the amount of usable/leasable space. From that standpoint, the building is inefficient, Harrison said. But with approximately half of the building serving as PAE Engineers’ new headquarters, team members were able to discuss appropriate lease rates, Harrison added.

Construction

The structure is primarily made of cross-laminated timber panels, heavy glulam structural columns and beams, and a concrete core. About 60-70 percent of the finished product, Sloop said, is the structure itself. Protecting that was challenging, he said, after the construction start date was moved from January to April. Some of the work planned for drier weather, like roofing, was pushed to wet-weather months, he said.

Additional complexity for construction came from the project team needing to ensure that items on the ILFI 鈥渞ed list鈥� 鈥� materials and chemicals considered 鈥渨orst in class鈥� to people and the environment 鈥� were not used. More than 3,000 products were vetted, Sloop said, to see whether they met Living Building Challenge requirements. The construction team had to develop a roofing system never used before, Sloop added.