Estimating the construction material stocks in two Canadian cities: A case study of Kitchener and Waterloo

Abstract

Growing worldwide population and expansion in urban land area are becoming global concerns. As a result of this growth, material consumption in cities is increasing to adapt with the needs and activities of the urban populations. Among the materials consumed, construction materials are responsible for the greatest share of material use in cities. To plan for the future demands of the urban population, policymakers should gain insight regarding current and future material use. Material stock accounting is a tool that can be used to provide an understanding of the historical material use in cities and the consumption patterns. In this research a bottom-up material stock accounting approach is used to estimate the quantity of construction materials embedded in the building, road and sidewalk stocks in Kitchener and Waterloo. These cities are located in the Region of Waterloo, one of the fastest growing urban areas and the tech-hub in Canada. In order to make these estimations, existing stocks from the early 1900s are considered and a growth pattern is presented from 2003 to 2018 using the existing data, and projected up until 2041. The results show that in 2018, there were around 65 Mt of materials in this area, which is a 23% growth from 2003. The per capita material consumption has also increased from 155 t/cap to 164 t/cap over this 15-year period. At the same time, building demolitions resulted in 2.572 Mt of construction materials turning into waste during this time period. Moreover, it is estimated that by 2041 an additional 12 Mt of materials will be added to the building, road, and sidewalk stocks of Kitchener and Waterloo. The results of this study will help cities take effective steps toward achieving circular economy and plan for implementing urban mining strategies.