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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.

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Seismic losses due to earthquakes have been shown to have significant economic, social and environmental consequences. Over recent years, research to predict potential economic and social impact due to seismic risk has been increasing. Recognizing that the traditional philosophy of life safety design can lead to extensive damage and demolition which has a large environmental cost, incorporating environmental impacts associated with the expected seismic damage over a building’s life is a key step as the building industry moves towards both sustainable and seismically resilient design. This paper introduces a framework that uses environmental indicators quantifying losses from seismic response that can then be used to advocate for a change in seismic performance objectives. First, existing literature and previously developed approaches for quantifying potential environmental impact due to seismic damage are summarized. Next, performance based earthquake engineering concepts are used to demonstrate a probabilistic approach to quantify potential environmental impacts using a range of environmental and resource use indicators over the life span of a case study building. In addition, a case study is presented to compare different environmental indicators between a Code Minimum building and the same building redesigned for a higher seismic performance. The majority of the composition of the environmental indicator values are from the inclusion of the non-repairable scenario, and from the repair activities, the majority of the impacts are from damage to drift sensitive components including curtains walls, partitions and elevators. For the Code Minimum building the non-repairable scenario contributes to between 8 to 11% the total seismic cost. For the Stronger Stiffer building, the non-repairable scenario contributes around 3% of the initial impact. Neglecting non-repairable scenarios does significantly reduce the potential environmental impacts when analyzing buildings designed for current code minimum structural standards.

The 2010/2011 Canterbury Earthquake Sequence resulted in severe loss and disruption in Christchurch, New Zealand due to liquefaction and damage from strong shaking. Following the earthquake, over 60% of concrete buildings with 3 + stories in the Christchurch CBD were demolished, resulting in a widespread displacement of people and business, an excess of $NZD 40 billion in losses, and significant environmental impacts from the demolition. Following the event, it was revealed that environmental impacts were not a direct consideration in demolition decision making. This paper provides a quantitative evaluation of the environmental impacts of the demolitions in Christchurch to highlight the importance of including environmental considerations when deciding between repair or demolition of a damaged building. First, the quantitative and qualitative factors that led to the demolitions following the Canterbury Earthquake Sequence are discussed to provide context for the argument that environmental impacts should be included in such considerations. Next, the environmental impacts of building demolitions in Christchurch are presented in terms of the embodied CO2 and energy in the building materials; the demolition process and waste disposal are not considered in this initial evaluation. Finally, a brief discussion on incorporating environmental impacts into the demolition decision making paradigm is presented. Moreover, consideration of environmental impacts of demolitions supports the need to move toward low-damage design in the future evolution of building codes.