Wood Product Carbon Storage Calculator

Carbon in a harvested wood product is a straightforward mass calculation: oven-dry volume multiplied by basic density gives dry mass, and dry mass multiplied by the carbon fraction gives stored carbon, which is converted to CO2 equivalent by 44/12, or 3.667. The IPCC default carbon fraction for wood is 0.47, though 0.50 is common in engineering practice and the true value ranges from about 0.45 to 0.52 by species. Basic density is the other lever: softwoods such as spruce and pine fall around 350 to 550 kg per cubic metre, temperate hardwoods 500 to 900, and dense tropical species such as ipe above 1,000. A cubic metre of 500 kg/m3 softwood at a 0.50 carbon fraction therefore holds about 250 kg of carbon, or roughly 917 kg CO2e. The second term is substitution, the emissions avoided when wood replaces a more energy-intensive material. Primary steel emits on the order of 1.8 tonnes CO2 per tonne and Portland cement roughly 0.6 to 0.9, whereas sawing and drying timber is comparatively low-energy. Published displacement factors vary widely with the assumed counterfactual and the electricity grid; this tool applies a conservative 1.2 tonnes of carbon avoided per tonne of carbon in product, at the low end of the literature. Two caveats matter. Storage is temporary: half-lives are around 35 years for sawnwood, 25 for panels and about 2 for paper, and landfilled wood decaying anaerobically releases methane. Recycling extends the storage period through cascading use rather than creating new carbon, so the extended lifespan shown here delays release but does not eliminate it.

Accounting for carbon in wood products lagged behind forest accounting because it was unclear which country should claim the stock - the one that grew the tree or the one that used the timber. The IPCC 2006 Guidelines for National Greenhouse Gas Inventories addressed this in Volume 4, Chapter 12, setting out harvested wood products as a distinct pool with alternative accounting approaches (stock-change, production and atmospheric-flow) and supplying first-order decay half-lives for sawnwood, wood panels and paper. The 2013 Kyoto Protocol supplement made reporting of the harvested wood products pool obligatory for developed-country parties in the second commitment period, which converted a research topic into a routine inventory line. The substitution argument developed separately in life-cycle assessment during the 1990s and 2000s and was consolidated by Roger Sathre and Jennifer O Connor in a 2010 meta-analysis of greenhouse gas displacement factors across published wood-versus-alternative comparisons. Interest surged with engineered timber. Cross-laminated timber was developed in Austria and Germany in the early to mid 1990s, with research by Gerhard Schickhofer at Graz University of Technology underpinning its structural approval, and building codes across Europe and North America were progressively amended to permit taller mass-timber structures. A 2020 paper by Galina Churkina and colleagues in Nature Sustainability framed buildings themselves as a potential global carbon sink, and certification schemes such as FSC and PEFC supply the sustainable-sourcing condition on which the net benefit depends.