A computational approach for estimating and minimizing construction-related and end-of-life carbon footprint of concrete structures

Abstract

This thesis presents the results of a comprehensive study conducted to develop reliable methods for estimating and minimizing the carbon emissions incurred in construction and end-of-life phases of a concrete structure. Through developing such methods, this thesis addresses an existing gap in the scientific literature which has been traditionally focused on cradle to site embodied carbon as well as operating carbon of buildings; and thereby complements the existing methods to enable achieving a full life cycle carbon emission estimate for concrete structures. A simplified computational method to estimate construction carbon emissions based on quantity take-offs from Building Information Models is presented. The method is then improved by accounting for uncertainty and the idling time of equipment to develop a more precise construction emission estimation method. The improved estimation method targets concreting and lifting operations as the most carbon-intensive operations in construction of a concrete structure. The estimation method is coupled with optimization models to minimize associated carbon emissions by optimizing concrete placing and lifting operations. The collected data from an actual construction project in Sydney are used to verify the presented carbon emission estimation methods. In addition, a framework to minimize the end-of-life carbon emissions of a concrete structure through estimating and comparing the emissions associated with different possible recycling and landfilling strategies is presented. The thesis finally concludes by highlighting the importance of incorporating the proposed methods as a part of a wider life cycle carbon footprint assessment method, to evaluate various design decisions in practice, by presenting a case involving selection of structural system for a building. The effects of different structural systems, height of the structure and type of material on associated life cycle carbon emissions are studied to highlight the importance of achieving a realistic estimate of carbon emissions as an important input into decision-making process in early design phase of construction projects.