Mass timber 'Living Building' planned for downtown Portland
The engineering firm PAE, which did the mechanical, electrical and plumbing engineering for Seattle's Bullitt Center, is forging ahead on its own Portland headquarters.
Behind the Pine Street Market food hall and Kell's Irish pub in downtown Portland, the structure will be built to Living Building standard, the hardest benchmark to achieve in energy efficiency. It should be the first certified Living Building in Portland. The PAE Living Building is being constructed with cross-laminated timber panels and glulam columns.
All of which means it won't be just another office building; it will be a tourist destination for engineers and architects. So many buildings now come with a story about building performance: how little energy it uses. The PAE Living Building will have added layers of narrative since it has a complex water system with composting toilets, and a large lithium-ion battery linked to its micro-grid electrical system.
As the wooden structure has flown up rapidly in recent weeks around the concrete core, we asked some of those involved in the design to start telling its story.
1. Which subcontractors are experienced in mass timber assembly, and what would they tell a colleague about how it compares to traditional concrete and steel?
Ed Sloop, Chief Estimator and Senior Project Manager, Walsh Construction Co.: Carpentry Plus is the mass timber framer on the PAE project, and they have done an excellent job. The PAE project team did holistically analyze concrete and steel frame structures for this project. Although the mass timber approach was somewhat more expensive than either the concrete or steel options, they decided the mass timber frame's benefits outweighed the costs.
In terms of assembly, the mass timber frame went together faster than concrete or steel thanks to meticulous attention to detail by all parties and the incorporation of as-built measurements of the concrete core into the model prior to fabrication of the wood components. The end result is a very high-quality frame: plumb, level, and square.
2. How is it working on a tight site at Northwest Second Avenue and Pine Street?
Ed Sloop, Chief Estimator and Senior Project Manager, Walsh Construction Co.: We were able to lease the parking lot to the north of the building as well as adjacent city sidewalk and street real estate, all of which has provided a little bit of elbow room to do the work as well as a valuable laydown area. The heavy CLT panels and glulam beams required a tower crane, which is coincidentally helpful when working on a tight site. Additionally, we're employing a custom scaffold system cantilevered off of the mass timber structure to access work on the west side of the building above the Pine Street Market.
3. Are there any ways mass timber is good for the environment beyond carbon sequestration?
Ed Sloop, Chief Estimator and Senior Project Manager, Walsh Construction Co.: This project procured Forest Stewardship Council (FSC) credits for all wood fiber needed to build the building. In addition to carbon sequestration, the forest's biodiversity, productivity, and ecological processes are maintained. Both concrete and steel manufacturing processes are energy-intensive, and they generate significant amounts of greenhouse gases, depending on the sources of energy employed in their respective processes, whereas trees grow over time via natural processes.
Another environmental differentiator is that the methods used to harvest the raw materials required to produce concrete and steel have arguably been more damaging to the ecosystems from which the materials come, than harvesting trees from a sustainably managed forest.
Marc Brune, Principal, PAE: If mass timber is sustainably harvested, there is a carbon sequestration benefit. This benefit comes from forest management and lumber management practices. If it is not sustainably harvested, then you cannot count on the benefit.
There is also an economic benefit to our communities by harvesting local lumber to build. One day we hope to see a demand for sustainably harvested mass timber in our urban centers that increases the market for sustainable timber management in our rural communities.
4. What special attention is PAE paying to the project, considering it will be their home office?
Marc Brune, Principal, PAE: Designing a headquarters is very important to PAE. The Living Building is about living our values, and we take a lot of pride in that as we design a sustainable office for our home in Portland. We anticipate it to be a superior work environment for our staff from what else is available on the market, from technology to air quality, daylighting, and biophilia. The entire building, at 58,000 square feet, will be net positive energy, net positive water, and include no Red List materials as defined by the International Living Future Institute under the Living Building Challenge (LBC). It will meet the most stringent sustainability standard in the world.
5. What will maintenance be like ongoing? Do living buildings require a lot more management? Can Portlanders do it?
Marc Brune, Principal, PAE: The biggest difference in maintenance will be in managing the building's sophisticated water systems, which help minimize its environmental footprint and will require somewhat more attention than a conventional building. We have a rainwater-to-potable system, a greywater system, and a composting system that will need active management. We will be hiring people from Portland to lead that work.
6. How do architects get up to speed designing in mass timber?
Kathy Berg, Partner, ZGF Architects: The use of wood is a tried and true system for ZGF. Wood has always been one of the most workable, natural and expressive building materials. Our work with wood predates the current influx of mass timber, as we have used wood and mass timber for decades in our practice. What has evolved is the supply chain and the technology available in the market today. We stay at the forefront of wood technology by creating relationships with key players in the supply chain, including forest owners, mills, and fabrication shops, to continually understand what is emerging and craftsmanship opportunities to expand the potential of wood. This includes making sure we specify wood that is sourced sustainably so that we have a supply for generations to come.
7. How do you see Old Town looking in 10 years? Right now it is unpleasant.
Jill Sherman, Partner, Edlen & Company: The PAE Living Building is going to bring more people and activity to the area on a day-to-day basis to the Historic District. We're excited to be in the neighborhood with the other businesses contributing to an already vibrant community.
8. Are living buildings a tourist attraction, like the Bullitt Center in Seattle? Is Portland ready for that?
Marc Brune, Principal, PAE: Like the Bullitt Center, we hope that people will want to come and see our building and the many unique systems that run it. We want to incorporate the community as much as possible for the specialized tours. For example, we are hoping to pair some tours with the university architecture programs to help lead tours through the building so that we can inspire the next generation of designers to follow in our path.
9. Anything else you'd like to share about the project?
Ed Sloop, Chief Estimator and Senior Project Manager, Walsh Construction Co.: The collaboration and performance among our people at Walsh Construction Co. and RDF Builders Co. as well as our partners at PAE, ZGF, Edlen & Company, and all our subcontractors, suppliers and consultants has been truly incredible and the key to the success of the project so far.
Reporter, The Business Tribune
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