The road to net-zero carbon buildings

On Nov. 6, Gov. Kate Brown issued “Executive Order 17-20, Accelerating Efficiency in Oregon’s Built Environment to Reduce Greenhouse Gas Emissions and Address Climate Change.” It lays out 17 directives intended to reduce carbon emissions from buildings, primarily through energy-efficiency measures.

Energy efficiency is important, particularly in light of the thousands of inefficient, 40-plus-year-old buildings that make up a majority of Oregon’s built environment. Buildings, through their construction and operation, are the single biggest contributor to carbon emissions – surprisingly, even worse than the transportation sector.

The goal of EO 17-20 is for all newly constructed state buildings to achieve carbon-neutral operations by the year 2022. That’s great. I hope we can get there. In fact, we should strive for all new buildings, state-owned or otherwise, to achieve carbon neutrality. Seems to me it wouldn’t be all that difficult.

Spurred by the popularity of the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) building-rating system, we’ve made huge strides in energy-efficiency technology over the past three decades. Rare is the new building today that isn’t heavily insulated and equipped with high-efficiency heating and ventilation systems. Many make good use of daylighting, are equipped with wastewater recycling systems or have some sort of clean-energy-generation system such as rooftop wind turbines or solar panels. Often, today’s new buildings have all the above and more. We’ve gotten so good at energy efficiency that soon the day will come when the larger source of carbon emissions is the energy consumed to make the materials used to construct the building in the first place.

That’s a point not lost on developers such as Ben Kaiser, whose cross-laminated timber (CLT) building, known as Carbon12, is nearly complete. Long before EO 17-20 was issued, Kaiser recognized the need to make his north Portland condominium project energy-efficient. As such, he designed into it things like exterior insulation that wraps the entire structure, so the building requires less energy to heat or cool. Large, highly efficient windows maximize daylighting while achieving better-than-code thermal efficiency. The condos in Carbon12 all have high-efficiency heat exchangers that allow warm air from one unit to mix with cooler air from another so energy isn’t wasted. And the building is solar-ready, with state-of-the-art systems in place for when residents choose to add solar panels.

Kaiser also understands that we need to go beyond just energy efficiency if we want to fully mitigate the carbon impacts of buildings. Because he chose wood as the primary material for Carbon12’s structure, he knows the energy-efficiency measures he incorporated will achieve their maximum effect much sooner than if he’d chosen more energy-intensive materials that don’t store carbon the way wood does.

The extremely low amount of energy needed to make wood products, and their incredible ability to store atmospheric carbon, gives timber buildings a head start. Before builders installed a single piece of insulation, the wood in Carbon12 had already offset about 800 metric tons of carbon dioxide emissions. Had Kaiser instead chosen to build with reinforced concrete, for example, it would have taken years, perhaps even decades, before the energy-efficiency measures he added to the building would have the chance to offset the emissions associated with making the concrete and the steel rebar.

We already know how to build highly energy-efficient buildings, and Gov. Brown is right to encourage faster adoption of those technologies. But let’s also remain cognizant of the very real gains that can be had by choosing building materials wisely. There’s no reason we can’t do both.

Timm Locke

Director of Forest Products

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