2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Dr. Ashutosh Bagchi, Concordia University, Canada
Dr. Andreas Athienitis
Energy is required in all phases of a building life cycle. Embodied energy and carbon emissions of a building are associated with the production, transportation, disposal, and recycling of materials, and during their construction and demolition. A cost-optimized structural design of individual members is obtained by selecting the quantities of materials that satisfy a certain design-code at a minimum cost. For a reinforced concrete structural element, concrete and rebars are optimized for cost. A member thus proportioned for a minimum cost may not always result in lower embodied energy and carbon emission. A different design approach is needed to reduce the embodied energy and carbon to a lower level. In this study, the objective functions for cost, embodied energy, and CO2emission were defined and used in the structural design of a set of RC flat-plate residential buildings with 5-, 10-, and 15-storeys, located in Montreal, Canada. The trade-off between the cost and two other variables was studied. It has been found that some significant reduction in embodied energy and CO2emission is possible for a small increase of the cost for the 5-, 10-, and 15-storey variants. For an optimized solution, the maximum reinforcement ratio of columns has been found to increase with the building height. A slab thickness taken 24% smaller than the minimum thickness specified by CSA 23.3-14 has been found to be most effective in meeting the objective of cost optimization and embodied energy and CO2emission reduction.