Cross-laminated timber, or CLT, is touted as a more sustainable option for building construction than concrete and steel. But is it really? The answer is complicated.
CLT is intended to replace concrete and steel whose production accounts for about 13% of global carbon dioxide emissions. Wood in CLT panels pulled CO2 from the atmosphere, and that carbon should remain locked up as long as the building stands.
Some forest scientists, climate modelers, and materials experts question how much of an environmental net gain results from using CLT to replace concrete and steel. Part of the concern relates to choices the lumber industry makes in forestry practices and manufacturing.
Lots of carbon gets dumped into the atmosphere when logs are transformed into CLT, they say. Sawmills and CLT plants typically burn bark, sawdust, and other wood wastes for heat, releasing carbon. Piles of branches, treetops, and smaller trees left behind after a harvest are often burned or left to decompose—releasing carbon into the atmosphere.
When it comes to combating global climate change, the mantra of “wood is good” may be simplistic.
Related Stories
Codes and Standards | Dec 16, 2020
New Specifications for Concrete Construction reference manual released
Scope expanded to include shotcrete, internal curing, mineral fillers, and recycled concrete aggregates.
Codes and Standards | Dec 15, 2020
Despite COVID-19 population flight, don’t write off big cities yet
Lure of urban life and jobs may draw people back after pandemic subsides.
Codes and Standards | Dec 10, 2020
Test method for vertical fenestration installation procedures updated
FGIA issues first update for document created in 2005.
Codes and Standards | Dec 10, 2020
Updated EPDs for Polyiso Roof and Wall Insulation; EPD for Polyiso High-Density Cover Boards published
Cover Boards EPD is an industry first.
Codes and Standards | Dec 9, 2020
Newly formed Rainscreen Association aims to be recognized authority on rainscreen assemblies
Will address innovations in material performance and building designs.
Codes and Standards | Dec 9, 2020
Investors want building resiliency plans and risk mitigation practices
Owners should assess risk, insurance coverage, and ability to withstand disasters.
Codes and Standards | Dec 4, 2020
OSHA cites more than 200 employers for COVID-19 violations
Agency releases guidance on lessons learned from pandemic inspections.
Codes and Standards | Dec 1, 2020
Pandemic spurs nearly 16 million people to move from major cities
Most of the movement seems permanent.
Codes and Standards | Nov 30, 2020
USGBC ready to catalyze LEED Positive future
New programs, updates will spur shift to regenerative strategies.
Codes and Standards | Nov 30, 2020
Updated spec for self-adhering flashing surrounding exterior fenestration products released
FGIA document was last updated in 2013.
