The objective of this project was to quantify and compare the environmental impacts associated with alternative designs for a typical North American mid-rise office building. Two scenarios were considered; a traditional cast-in-place, reinforced concrete frame and a laminated timber hybrid design, which utilized engineered wood products (cross-laminated timber (CLT) and glulam). The boundary of the quantitative analysis was cradle-to-construction site gate and encompassed the structural support system and the building enclosure. Floor plans, elevations, material quantities, and structural loads associated with a five-storey concrete-framed building design were obtained from issued-for-construction drawings. A functionally equivalent, laminated timber hybrid design was conceived, based on Canadian Building Code requirements. Design values for locally produced CLT panels were established from in-house material testing. Primary data collected from a pilot-scale manufacturing facility was used to develop the life cycle inventory for CLT, whereas secondary sources were referenced for other construction materials. The TRACI characterization methodology was employed to translate inventory flows into impact indicators. The results indicated that the laminated timber building design offered a lower environmental impact in 10 of 11 assessment categories. The cradle-to-gate process energy was found to be nearly identical in both design scenarios (3.5 GJ/m2), whereas the cumulative embodied energy (feedstock plus process) of construction materials was estimated to be 8.2 and 4.6 GJ/m2 for the timber and concrete designs, respectively; which indicated an increased availability of readily accessible potential energy stored within the building materials of the timber alternative.
European experience shows that Cross-Laminated Timber (CLT) can be competitive in mid-rise and high-rise buildings. Although this system has not been used to the same extent so far in North America, it can be viable wood structural solution for the shift towards sustainable...
Recent changes to the National Building Code of Canada (NBC), and a trend towards more diversified housing options, have meant that many Canadian jurisdictions are acting quickly to capture the environmental, economic and social benefits of higher wood buildings. The 2015 NBC now permits wood frame construction to be 6 storeys high. Today, already 75% of Canadians live in jurisdictions that allow 6 storey wood frame construction. With the overall benefits of using wood as a building material well documented, Atlantic WoodWORKS!
studied the opportunities for 6 storey wood construction in Atlantic Canadian Centres. The research included a comprehensive market study and projections for mid-rise demand in
four major centres in Atlantic Canada, a review of recent and upcoming planning changes in major Atlantic Canadian cities and a full cost analysis, comparing wood construction to three
other construction methods in use in the Atlantic market using a real-life wood mid-rise structure built by an experienced builder.