The Estimated Carbon Cost of Concrete Building Demolitions following the Canterbury Earthquake Sequence

Abstract

The 2010/2011 Canterbury Earthquake Sequence caused severe economic impacts and community disruption in Christchurch, New Zealand due to damage from liquefaction and strong shaking. Following the earthquake, approximately 7500 dwellings and 1400 commercial properties were demolished, resulting in 4 million tons of building debris. Using the Canterbury event, and the subsequent building demolitions in Christchurch as a case study, this research quantifies the embodied carbon and energy costs associated with the post-earthquake demolition of buildings prior to the end of their intended design life. A building data set consisting of 142 reinforced concrete buildings that were demolished following the event was used to estimate the total amount of structural and non-structural debris resulting from the demolitions. A framework was developed to calculate the global warming potential of the demolished buildings considering embodied CO2 and energy in the building materials, impacts of the processes used in construction of the building, and CO2 emissions of the transport and waste management processes. A life cycle assessment tool was used to calculate the environmental costs in the production and transport module, the spatial distribution of the waste based on the building locations was calculated to determine transport distances to disposal facilities, and the waste disposal and recycling benefits were calculated using values from a life cycle inventory database. The results of the research revealed the demolition of concrete buildings had staggering environmental costs in terms of embodied CO2 and energy, which make the case for both resilient design strategies that reduce waste and pollution following earthquakes, and incorporating environmental impacts into demolition decisions.