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 | May 16, 2018
New resources offer tips on off-site construction
NIBS documents address using pre-cast concrete, and commercial and legal considerations of modular construction.
Codes and Standards | May 15, 2018
Blast testing of loaded mass timber structures yields positive results
Four tests covered a spectrum of blast loads.
Codes and Standards | May 14, 2018
Maryland makes general contractors liable for failure of subs to pay employees
GCs could have to pay for up to three times the wages owed.
Codes and Standards | May 10, 2018
Data collection, machine learning boost building efficiency
Sensors, software algorithms squeeze out waste.
Codes and Standards | May 9, 2018
OSHA and state safety agencies write more than 100 silica citations in 6 months
Actions tending to come with investigation of other site conditions.
Codes and Standards | May 8, 2018
Powerhouse coalition builds energy positive buildings
The goal: build buildings that provide more power than they cost to build, run, and demolish.
Codes and Standards | May 7, 2018
Plan advances in Los Angeles for Climate Emergency Mobilization Department
Would oversee efforts to reduce greenhouse gas emissions across the city.
Codes and Standards | May 3, 2018
Data collection, machine learning boost building efficiency
Sensors, software algorithms squeeze out waste.
Codes and Standards | May 2, 2018
Energy Department releases Updated EnergyPlus and OpenStudio building energy modeling tools
The tools can now accept input in epJSON format.
Codes and Standards | May 1, 2018
ASHRAE publishes new energy simulation-aided design standard
Requires building energy modeling during schematic design.