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Carbon accounting is likely one of the most vital however least understood features of the dialogue about cross laminated timber. The declare that CLT is carbon damaging depends upon how one defines system boundaries and the way accounting guidelines are utilized. Bushes take up carbon as they develop, storing it of their fibers. When these bushes are harvested and transformed into structural panels, that carbon stays locked in place for so long as the constructing stands.
The sequence thus far has constructed a transparent case for mass timber as Canada’s quickest lever to handle housing, financial system, and local weather collectively. The opening article argued that CLT and modular development can double housing provide whereas slicing embodied carbon. The second examined Mark Carney’s Construct Canada Houses initiative and confirmed how authorities can act as an anchor purchaser to show coverage into actual housing output. The third mapped out Canada’s mass-timber playbook, stressing the necessity for an built-in worth chain from sawmills to modules. The fourth explored how CLT substitution bends long-term cement and metal demand curves, making heavy trade decarbonization extra achievable.
Emissions are launched at each step of the method, from harvesting and transport to drying, adhesives, and meeting. The stability between saved carbon and emitted carbon is what issues, and the stability is putting. Environmental product declarations, or EPDs, for CLT produced in Canada already present that extra carbon is saved than emitted, cradle to gate. That makes the product web damaging earlier than it even reaches a development web site.
The Element5 EPD is a living proof. Course of emissions related to producing a cubic meter of CLT are on the order of 120 kilograms of CO2. That features vitality for harvesting and transport, kiln drying, adhesive manufacturing, and meeting. In contrast, that very same cubic meter of CLT shops near a ton of CO2 absorbed throughout tree progress. The stability is damaging by a large margin. But many requirements require that the saved carbon be reported individually, not netted out in opposition to emissions. The logic is that the storage is non permanent till the top of life destiny of the fabric is understood. If the wooden is incinerated, that carbon is launched. Whether it is landfilled, a few of it’s emitted as methane with out seize. Whether it is reused in one other constructing or sequestered in merchandise like biochar, it could possibly stay locked away for even longer. The official accounting treats storage as conditional, however the sensible local weather profit is obvious when timber is utilized in lengthy lived buildings.
The analysis is simple. Biogenic carbon is actual, however accounting frameworks are conservative about crediting it. This warning results in under-recognition of the local weather advantage of mass timber in present applications. Insurance policies and requirements might change that. Canada ought to require EPDs for all structural supplies in order that embodied carbon is transparently measured and in contrast. Applications ought to reward long run storage in buildings by granting credit score for timber that’s anticipated to stay in place for 50 to 100 years. Alignment with ISO and EN requirements would guarantee credibility whereas Canadian coverage could lead on by integrating recognition of storage into constructing efficiency targets. Some European applications already do that by counting the storage advantage of wooden when evaluating low carbon buildings.
Making CLT carbon damaging in follow depends upon greater than accounting. It depends upon decisions throughout the lifecycle. Designing buildings for longer life ensures that carbon stays saved for a lot of a long time. Designing for reuse permits panels and beams to be disassembled and positioned into new buildings moderately than downcycled or burned.
Finish of life administration is crucial. If panels are incinerated with out carbon seize, saved carbon is misplaced. If they’re landfilled with out gasoline administration, some portion escapes as methane. Higher outcomes come from reuse, recycling, or conversion into secure kinds like biochar. Landfills with methane seize can even mitigate emissions. Canada can set requirements that drive builders and municipalities towards these outcomes. A nationwide strategy to EPDs for timber that features these pathways would assist codify the carbon profit.
Complementary decarbonization of the provision chain strengthens the case additional. Diesel gear in forests, fossil fuel-powered kilns, and petrochemical adhesives all add to the constructive aspect of the emissions ledger. Electrifying harvesting and hauling, switching kilns to biomass or warmth pump methods, and shifting bio-based adhesives from pilot to manufacturing all cut back course of emissions. The result’s a decrease constructive determine within the EPD and a stronger damaging stability when paired with saved carbon. Canada’s electrical energy grid is already comparatively clear and will probably be web zero by 2035 below federal targets. That implies that electrification interprets immediately into reductions. The chance is to drive that constructive quantity down towards zero, making the damaging storage worth stand out much more.
Charts that present the breakdown assist make clear the story. A typical EPD presents constructive emissions in a single column and biogenic storage in one other. The distinction is what issues. Waterfall diagrams of emissions from harvesting to finish of life present the place reductions may be made and the way storage dominates the stability. Coverage charts can map completely different credit score pathways, exhibiting what’s acknowledged below present requirements and what could possibly be acknowledged if applications evolve. Collectively these visible instruments make the case that CLT isn’t solely web damaging in follow, however needs to be counted that approach in official frameworks.
Dangers stay. World accounting requirements should not constant. Some nations require EPDs, others don’t. Some credit score storage, others deal with it individually. With out harmonization, comparisons throughout merchandise and geographies are tough. Skepticism about permanence will proceed, particularly from industries that compete with timber. Adoption of EPD necessities may be gradual, and a few builders could resist extra reporting burdens.
However the enablers are additionally current. There may be rising demand from builders and buyers for clear embodied carbon knowledge. European precedents present that storage may be credited responsibly. Canada’s clear electrical energy and sustainable forestry base make it nicely suited to steer in demonstrating a carbon damaging timber trade.
The conclusion is that CLT already shops extra carbon than it emits, cradle to gate. With electrified provide chains and sustainable forestry practices, its web local weather profit is simple. Accounting methods must evolve to mirror this actuality and to reward long run carbon storage in buildings. After they do, CLT won’t solely be acknowledged as carbon damaging however may even be incentivized in coverage and procurement. Canada has a possibility to steer in marrying sustainable forestry, industrial electrification, and clear carbon accounting. The end result can be a constructing materials that’s strongly carbon damaging in actual fact and in legislation, aligning the wants of housing, financial system, and local weather.
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