All Wood Construction
The Case for Innovative Wood Products
Improving buildings’ operational energy efficiency is a vital first step in addressing the climate crisis, but the job doesn’t end there. To radically reduce—or even erase—the total carbon footprint of OPAL buildings, we’re also working to zero out the carbon debt of the materials that go into their construction. In most applications, that means shifting from energy- and carbon-intensive building materials like fiberglass, foam, and concrete to those made from wood.
When we launched our firm in 2008, Passive House was virtually unknown in the U.S. But in this approach to building design and construction we recognized something that architects and builders had been working toward since at least the 1970s: a simple, comprehensive formula that yields a radical 10X improvement in energy efficiency for space heating while also optimizing comfort and indoor air quality. Because buildings are responsible for some 44 percent of all carbon emissions worldwide, reducing energy demand, and therefore carbon emissions, was—and remains—a clear imperative.
Since our firm’s founding, the Passive House formula has been the basis of every design we’ve produced, saving the equivalent of well over 150,000 gallons of oil to date compared with the same square footage constructed to code standard.
The Next Challenge: Accounting for Embodied Carbon
Having established the efficacy of Passive House principles in minimizing a building’s operational energy use and carbon emissions, we believe it is now time to address the substantial hidden environmental costs of the materials that make up the building. This includes the crucial impact of embodied carbon, the carbon emitted during the manufacture, transportation, and eventual disposal of those construction materials.
A prime example is foam insulation, a component frequently used in Passive House wall assemblies. Wrapping a building shell in a continuous jacket of exterior insulation dramatically reduces thermal bridging, and foam insulation boards perform relatively well in that role — until one considers their full environmental cost. Specifically, it requires 8 to 10 years of operational carbon savings to pay off the carbon debt of these other insulation products.
Based entirely on fossil fuels as both the raw material and the energy source for their manufacture, EPS and other plastic foams arrive at the construction site with a significant carbon footprint. Impossible to recycle, plastic waste clogs our landfills, fouls our oceans, and is now being detected in our food supply and even in our bodies. While foam will continue to play a role in energy efficient construction in the foreseeable future, especially in below-grade applications, there is good reason to seek alternatives when possible.
And foam is only one material. As the Passive House movement matures into an industry, we believe the next step is to account for the full environmental impact of all of our material choices, including plastics, metals, concrete, wood, and everything else that goes into constructing a building. To that end, OPAL is taking advantage of sophisticated analytical tools that allow us to model, compare, and optimize our building designs not only for operational energy performance, but also for LCA (life cycle assessment), which also accounts for embodied carbon and CO₂e (carbon dioxide equivalent) of the materials that make up the building.
To make a meaningful contribution to solving the climate crisis, it is clear that building materials must not only reduce operational energy, but also minimize the embodied carbon they add to the building. OPAL is engaged in a firm-wide initiative to radically reduce the amount of embodied carbon in the buildings we design, and we have consistently found that the most effective way to do so is by substituting wood and wood-based products for conventional energy- and carbon-intensive materials. Wood products, with their typically minimal processing and low embodied energy, also sequester CO₂, with the potential to store more carbon than is released to the atmosphere during their manufacture and shipping.
