Net Zero Buildings

Frequently Asked Questions

About Wood’s Carbon Footprint

• Do the carbon emissions produced by forestry activities negate the carbon storage benefits of wood and wood products?
  Carbon emissions associated with forestry activities do not exceed the amount of carbon stored in wood and wood products. Studies show that the emissions associated with wood production, transportation, and harvesting are relatively small in most cases. One such study of southeastern U.S. loblolly pine found that emissions from management and harvest activities accounted for only 1.6% of the total carbon stored in the wood products and the managed forest.

• Is using wood the best carbon mitigation pathway? Isn’t it better to let trees grow?
  Both are valid ways to store carbon but only one creates wood products for buildings—buildings that will store carbon throughout their service lives––while also replanting new trees after harvesting to continue the cycle of carbon sequestration. The United Nations Food and Agriculture Organization report, “Forestry for a Low-Carbon Future,” lists six key strategies for integrating forests and wood products into climate change strategies––items 2 and 3 are both important to a low-carbon future:

  1. Plant more trees
  2. Increase carbon density/stocks in existing forests
  3. Increase wood product carbon storage
  4. Reduce deforestation and degradation
  5. Use biomass for energy, replacing fossil fuel
  6. Use wood products in construction materials, avoiding fossil fuel emissions in manufacturing products with higher combined emissions

• Doesn’t cutting down trees to manufacture wood products reduce forests’ ability to store carbon?
  The carbon storage of wood offsets some of the temporary reductions of carbon stock in forests, which will re-grow and continue to absorb carbon from the atmosphere. Because the rate of carbon sequestration is greater during the years of young, vigorous tree growth, a cycle of harvesting and replanting maintains the forest's ability to serve as a carbon sink.

• How does wood’s carbon footprint compare to the other primary structural materials, like concrete or steel?
  Of the three primary structural materials used in construction, manufacturing lumber is the least energy intensive, at 33kg net carbon emissions per production ton, compared to 220kg for recycled steel, 265kg for concrete, and 694kg for virgin steel. Using life cycle analysis, Oregon State University researchers found that substituting wood for concrete and steel in commercial buildings cut GHG emissions by an average of 60%.

• I’ve heard wood stores carbon. How does that work?
  Wood is comprised of ~50% carbon by dry weight. That means wood in a building stores carbon that would otherwise be emitted back into the atmosphere. Wood continues to store carbon for the life of a structure, minimizing a building’s carbon footprint. When stored carbon is considered along with embodied carbon, many wood products have a negative CO²eq value when sourced from forests with stable or increasing carbon stocks.