Using wood reduces the carbon footprint of buildings in two key ways—through carbon storage and avoided greenhouse gas emissions.
As trees grow, they absorb carbon dioxide (CO2) from the atmosphere, release the oxygen (O2), and incorporate the carbon into their wood, leaves or needles, roots and surrounding soil. One of three things then happens:
- When the trees get older, they start to decay and slowly release the stored carbon.
- The forest succumbs to wildfire, insects or disease and releases the carbon quickly.
- The trees are harvested and manufactured into products, which continue to store much of the carbon. (Wood is 50 percent carbon by dry weight.1) In the case of buildings, the carbon is kept out of the atmosphere for the lifetime of the structure—longer if the wood is reclaimed at the end of the building’s service life and re-used or manufactured into other products.
In all of these cases, the cycle begins again as the forest regenerates and young seedlings once again begin absorbing CO2.
The other aspect to wood’s light carbon footprint is the fact that wood products typically require less energy to manufacture than other building materials, and most of that comes from renewable biomass (e.g., bark and other residual fiber) instead of fossil fuels. Substituting wood for fossil fuel-intensive materials is a way of avoiding greenhouse gas emissions.
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