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Summary

Part 1 Environmental Footprint of CLT – Preliminary Findings In this part, we approximately determine some quantified environmental characteristics of CLT as a construction material, without conducting a full life cycle assessment (LCA). Finding no existing comparative literature on CLT, we attempt several approaches to estimate the footprint of CLT and the comparison to concrete. Using existing LCA data on Canadian glulam as a proxy, we look at the footprint of the material itself compared to the materials in reinforced concrete, and at the material in a mid-rise building compared to concrete. We then modify glulam LCA data to approximate an LCA for a CLT floor section and compare it to a functionally equivalent concrete floor section. In all these cases, we estimate that the CLT version will substantially outperform concrete in every environmental metric addressed by LCA. Part 2 Potential Indoor Air Quality Impact of Using CLT in Buildings – Preliminary Findings Five cross-laminated timber products with different thicknesses and glue lines were tested for their volatile organic compounds (VOCs) including formaldehyde and acetaldehyde emissions in order to assist engineers and builders to better select their construction materials with less impact on indoor air quality. Emissions were evaluated according to ASTM D 5116 and were collected after 24 hours of samples exposure in the small chamber. No correlation was observed between the cross-laminated timbers’ thicknesses or glue lines and the amount of emitted individual VOCs (iVOCs), including formaldehyde and acetaldehyde or total VOCs (TVOCs). All five CLT products showed very low levels of iVOC and TVOC emissions; most of the detected VOCs consisted of terpene compounds originating from the softwood furnish used to manufacture the laminated timber products. Thus, their impact on indoor quality when CLT is used for construction will be very minor, if any. In terms of evaluating the product’s impact on indoor air quality, one can easily conclude that it would be negligible, if any. The five cross-laminated timber products’ TVOCs and formaldehyde 24-hour results were generally lower than those set forth by some European emissions’ labelling systems. Also, the European E1 grade for wood products’ formaldehyde emissions set at 0.1 parts per million (ppm) or 100 parts per billion (ppb) is 6 to 20 times higher than those measured from the cross-laminated timber products. By July 2012, the CARB (California Government standards) Phase 2 enforcement for all composite products will be completed and formaldehyde emission limits will vary from 0.13 ppm (130 ppb) for thin MDF (medium density fibreboard) to 0.05 ppm (50 ppb) for hardwood plywood with composite core (HWPW-CC). Comparing these limits to those from the cross-laminated timber products, one can conclude that these products easily meet the most stringent CARB limit of 50 ppb.FORIN

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