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Carbon accounting is without doubt one of the most necessary however least understood elements of the dialogue about cross laminated timber. The declare that CLT is carbon destructive depends upon how one defines system boundaries and the way accounting guidelines are utilized. Timber 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 collection to date has constructed a transparent case for mass timber as Canada’s quickest lever to deal with housing, financial system, and local weather collectively. The opening article argued that CLT and modular building can double housing provide whereas slicing embodied carbon. The second examined Mark Carney’s Construct Canada Properties 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 business decarbonization extra achievable.
Emissions are launched at each step of the method, from harvesting and transport to drying, adhesives, and meeting. The steadiness between saved carbon and emitted carbon is what issues, and the steadiness is placing. 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 internet destructive earlier than it even reaches a building website.
The Element5 EPD is a working example. Course of emissions related to producing a cubic meter of CLT are on the order of 120 kilograms of CO2. That features power for harvesting and transport, kiln drying, adhesive manufacturing, and meeting. Against this, that very same cubic meter of CLT shops near a ton of CO2 absorbed throughout tree progress. The steadiness is destructive 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 tip 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 may stay locked away for even longer. The official accounting treats storage as conditional, however the sensible local weather profit is evident when timber is utilized in lengthy lived constructions.
The analysis is easy. Biogenic carbon is actual, however accounting frameworks are conservative about crediting it. This warning results in under-recognition of the local weather good thing about mass timber in present applications. Insurance policies and requirements may 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 good thing about wooden when evaluating low carbon buildings.
Making CLT carbon destructive in observe depends upon greater than accounting. It depends upon selections 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 constructions quite than downcycled or burned.
Finish of life administration is essential. If panels are incinerated with out carbon seize, saved carbon is misplaced. If they’re landfilled with out fuel administration, some portion escapes as methane. Higher outcomes come from reuse, recycling, or conversion into secure kinds like biochar. Landfills with methane seize also can mitigate emissions. Canada can set requirements that drive builders and municipalities towards these outcomes. A nationwide method to EPDs for timber that features these pathways would assist codify the carbon profit.
Complementary decarbonization of the availability chain strengthens the case additional. Diesel tools in forests, fossil fuel-powered kilns, and petrochemical adhesives all add to the constructive facet of the emissions ledger. Electrifying harvesting and hauling, switching kilns to biomass or warmth pump techniques, and transferring bio-based adhesives from pilot to manufacturing all scale back course of emissions. The result’s a decrease constructive determine within the EPD and a stronger destructive steadiness when paired with saved carbon. Canada’s electrical energy grid is already comparatively clear and will likely be internet zero by 2035 underneath federal targets. That implies that electrification interprets straight into reductions. The chance is to drive that constructive quantity down towards zero, making the destructive 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 will be made and the way storage dominates the steadiness. Coverage charts can map totally different credit score pathways, exhibiting what’s acknowledged underneath present requirements and what might be acknowledged if applications evolve. Collectively these visible instruments make the case that CLT isn’t solely internet destructive in observe, however must be counted that manner in official frameworks.
Dangers stay. International accounting requirements aren’t 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 will be gradual, and a few builders might resist further 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 will be credited responsibly. Canada’s clear electrical energy and sustainable forestry base make it nicely suited to steer in demonstrating a carbon destructive timber business.
The conclusion is that CLT already shops extra carbon than it emits, cradle to gate. With electrified provide chains and sustainable forestry practices, its internet local weather profit is simple. Accounting techniques have to evolve to replicate this actuality and to reward long run carbon storage in buildings. Once they do, CLT is not going to solely be acknowledged as carbon destructive however can even be incentivized in coverage and procurement. Canada has a chance to steer in marrying sustainable forestry, industrial electrification, and clear carbon accounting. The consequence can be a constructing materials that’s strongly carbon destructive actually and in legislation, aligning the wants of housing, financial system, and local weather.
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