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Five years ago, PAE Engineers, ZGF Architects, Edlen & Co., and Walsh Construction set out to construct a building able to meet today’s most advanced sustainability metrics.

In November 2021, they completed that building.

Now, the team must wait for a full year of operation and data collection before receiving word if the PAE Living Building has successfully achieved the International Living Future Institute’s Living Building Challenge.

Systems inside the building allow it to produce its electricity, capture and treat all its water, operate efficiently, and more. But to solve big challenges, the project team first needed to turn to the little details.

One valve after another

In the back of the PAE Living Building, on the ground floor, is the mechanical room. In the far corner are two rows of tall, blue composting machines 鈥� each capable of holding five gallons of liquid waste. Above each of the 20 composters is a black-and-yellow valve.

After a 70-gallon sump fills with waste from toilets (about once per day from typical use), one composter’s valve opens for 10 seconds 鈥� waste pumps in 鈥� and then closes. The valve at the next composter then follows suit, and on down the line until the sump is empty. The system ensures that each composter fills evenly.

鈥淚f you use one composter too much, you can overload it, and then just like backyard compost would turn into a wet soggy mess,鈥� PAE principal and lead engineer Marc Brune said. 鈥淚t’s even worse here.鈥�

The setup also allows the composters to be at the back of the building. The project team could have relied on gravity instead of pumps, ZGF principal Justin Brooks said, but that would have required alignment of the restrooms and the composters throughout the building and thus a restricted floor plan.

Project financing relied on investments, so it was important for the structure to perform not only sustainably but also economically. A 2,365-square-foot mechanical room did not help the cause. However, use of a nutrient recovery system created more leasable space.

All liquid from the urinals drains into the system, beginning with a 1,000-gallon collection tank. The liquid then runs through a distillation column (about once a month), which separates the leachate from the urine and creates both liquid and powder fertilizers that will be sold.

Without separation of the urine from the urinals and the waste from the toilets, the building would have needed 23 composters, Brune said. Each composter costs substantially more than $10,000, said Ed Sloop, chief estimator for Walsh Construction, so use of just 20 represented a significant cost savings.

As far as the project team knows, no other Living Building has a nutrient recovery system.

Nuances in materials

Holding the 58,000-square-foot structure together are cross-laminated timber panels, glulam structural columns, and beams with concrete shear walls in the center for additional reinforcement.

鈥淚t’s basically a wood building wrapped around a concrete building,鈥� Sloop said.

So, when it came to the stairway that travels up the center of the building. Brooks said the team needed to make a design decision: Should the wood and the concrete touch? In the case of the stairway, they do not.

Also, by not adding finishes to connect the surfaces, Brooks said, the team limited its use of materials, energy, carbon 鈥� and money.

Similarly, CLT panels lay flat across the floor beams, and just a thin line separates them. But to ensure that it would be a thin line and not a gap, KPFF engineers and Walsh Construction team members needed to engage in hours of back-and-forth and prep work.

Each glulam beam is engineered to have a precise arch (camber) so that only a certain amount of it leaves when the CLT is placed. Then the rest of the camber comes out from the concrete’s weight from the roof, leaving a flat line.

A lot of the back-and-forth, Sloop said, was on how to pour the concrete and ensure the weight was proportioned correctly for the beams.

鈥淲e said, 鈥極K, we’re going to pour it uniform thickness and trust the math,’鈥� he added. 鈥淎nd it came out great. You can walk around 鈥� and you don’t see 鈥榮miles’ because it just landed flat.鈥�

Hidden systems

Small vents scattered atop the building are the only visible markers of the unique system that allows the roof to 鈥渂reathe.鈥�

The day the roof was placed there was 鈥渂ad weather,鈥� Sloop said, and a vapor barrier had to go down. When the concrete top was poured, an abundance of moisture was left under it and within the exposed structure.

鈥淲e couldn’t get a warrantable roof unless we could do something with the moisture,鈥� Sloop said.

That difficulty as well as the one posed by the Living Building Challenge‘s restrictive Red List of 鈥渨orst in class鈥� materials led to a new roofing system being invented for the project. A special waffle-pattern insulation allows air to circulate under the membrane. The vents atop the roof then let the air escape.

鈥淵ou don’t see it; it’s not sexy,鈥� Sloop said, 鈥渂ut it’s super important to how this building got built and the longevity of the roof.鈥�

A few windows in the walls give peeks at the inner workings, but most of the systems are tucked away.

鈥淚 just think about how much is contained in a relatively small container,鈥� Sloop said. 鈥淭here are more systems on this building than any building I have ever participated in.鈥�

Completion of the PAE Living Building is realization of a dream, Brune said, especially since it holds the engineering firm’s new headquarters.

鈥淚’m hoping we’ve pushed the bar a little further and (we’re) a lot closer to seeing a lot more of these because of this project,鈥� he said. 鈥淭o me, it’s just an inspiration to work in here every day that I come in.鈥�