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Metropolis Editors, Natural Habitat, sustainability, sustainable architecture

METROPOLIS Introduces Natural Habitat, a Sustainable Homes Video Series

The series debuts with a tour of a tranquil upstate New York retreat designed with Passive House principles.

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COURTESY PORT OF PORTLAND

February 21, 2025

How Upstream Calculated the Carbon Footprint of Portland’s New Mass Timber Terminal

ZGF’s Portland Airport expansion partnered with the University of Washington’s Applied Research Consortium to pioneer a groundbreaking sustainability tool.

By: Francisco Brown

ZGF, in collaboration with the University of Washington’s Applied Research Consortium, has developed an innovative wood life cycle calculator called UpStream. This spreadsheet tool helps designers assess biogenic carbon storage, forest carbon sequestration, and end-of-life scenarios for wood products. Portland Airport’s wood roof served as a perfect test bed for this tool.

“We were trying to understand upstream carbon dynamics of mass timber—going back to the forest and connecting everything,” says Jacob Dunn, ZGF’s principal. UpStream aims to integrate carbon impacts from forest management into life cycle analyses (LCA) and allows for custom end-of-life scenarios for wood products.


The challenge, Dunn explains, was how to quantify carbon in forests properly and attribute it to wood products. ZGF identified two key issues: Many end-of-life scenarios aren’t modeled at all, and when they are, there’s an assumption of biogenic carbon neutrality. This assumes that as long as the forest regrows, carbon emissions from wood in landfills or incinerators will be offset by tree regrowth. However, the team wanted more flexibility and accuracy. For example, local conditions in Portland meant a default 50 percent of wood goes to landfills and 50 percent to incineration, rather than relying on accurate figures. That’s why the airport’s design, sourcing, and construction were crucial for developing this new tool. 

COURTESY EMA PETER

3 Goals for Climate-Smart Forestry

“We needed to rethink biogenic carbon,” Dunn says, explaining that the forest and built environments are interconnected. The wood in a building isn’t isolated but part of a larger carbon cycle that must be optimized for climate-smart forestry. The goal is to increase the amount of carbon stored in wood, reduce emissions by substituting wood for steel or concrete, and promote the reuse of durable wood products.

The tool’s basic approach involves calculating the carbon sequestration in a forest over time and dividing that by the amount of wood harvested. Using both observed satellite data and NASA resources, the team measured how much biomass grew on specific lands over the past 30 years. Satellite tools like lidar could analyze forest growth on a per-pixel basis, tracking changes in carbon stocks across small or large tracts of land.

At Portland Airport, the team connected this data with their wood sourcing, applying carbon factors to the wood based on its origin. “This was the ‘aha’ moment,” Dunn says, as they began quantifying how much carbon each forest saved or emitted. The variation was significant depending on the data set and forest in question. These discrepancies also opened the conversations about forest stabilization and rotational patterns as regeneration practices. 

According to the ZGF team, the case study cemented three principles for climate-smart sourcing in the region: first, understanding how harvest practices in the Northwest can influence carbon storage; second, evaluating whether the forest is increasing its carbon stocks over time; and third, working with definitions and frameworks to ensure that forests are managed sustainably, stabilizing carbon where needed.

By integrating these data sets, UpStream has provided the tools to analyze and optimize wood’s role in the carbon cycle. Portland Airport is proof of the concept’s potential to guide climate-conscious building practices for the region and the entire nation. 

a screen shot of the Upstream Carbon Calculator tool
COURTESY UPSTREAM

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