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As the world moves towards a carbon-free future, cities have been identified as key hubs for change. They have the greatest ability to quickly develop more efficient systems and implement climate change mitigation policies. Moreover, cities will become the destination of a population migration as humanity grows globally to a population of 11 billion. In this case study, we show that the applicability of the Ecological Footprint, an overarching outcome measure of resource consumption, for targeting climate change mitigation in cities. We focus on the carbon Footprint subcomponent of the Ecological Footprint, and further translate and disaggregate the carbon Footprint into detailed classification of individual consumption according to purpose (COICOP) and analyze the Footprint of consumption associated with each of these categories for 15 Canadian cities according to census metropolitan area (CMA), from each province. The Ecological Footprint of CMAs was calculated from the consumption land use matrix (CLUM) of Canada, by scaling results according to the annual national survey of household spending from 2010 to 2015. The expenditure in electricity was also scaled with the carbon intensity factor. Our findings indicate that the carbon Footprint remains the largest contributor of the Ecological Footprint of CMAs. The carbon Footprint associated with housing varied significantly with the source of electricity production. CMAs relying on renewable energy sources have a substantially lower carbon Footprint than those relying on fossil fuel energy. The carbon Footprint associated with the operation of personal transportation was the second largest among all consumption categories. Financial services is the largest share of the carbon Footprint from service consumption. Clothing consumption caused most of the goods’ carbon Footprint. A better understanding of urban planning of Canadian CMAs and promoting local consumption will improve carbon mitigation and long-term sustainability. [ABSTRACT FROM AUTHOR]

• A retrofit selection strategy employing economic and environmental decision criteria was proposed. • Building energy retrofits were evaluated through a life cycle thinking approach. • Retrofits with operational emissions savings may not be beneficial when considering life cycle impacts. • Energy mix and the heating system of the house greatly impact the effectiveness. • Retrofit selection changes with stakeholder priorities on environment and economics. Improving the energy performance of buildings has been a much-discussed topic over the past few decades. With the current focus on climate change mitigation, emissions reduction has also come to the forefront of this discussion. Retrofitting is an option to improve the energy and emissions performance of buildings. However, in the residential building stock, retrofit planning for existing buildings faces many complexities due to variations in climatic conditions and macro-environment as well as the presence of multiple stakeholder groups. Thus, in identifying solutions, it is necessary to take a holistic perspective that covers these different dimensions. In this paper, commonly used building energy retrofits were evaluated through a life cycle thinking approach. The performance of various retrofit options applicable for single family detached housing were evaluated using the HOT2000 energy simulation software package under the varying climatic conditions and energy supply scenarios across Canada. The retrofits were evaluated in terms of the additional investment, energy use and cost reduction achieved over the life cycle, and life cycle emissions reduction. The findings indicate that the provincial energy mix and the heating system of the house (i.e. electric or natural gas) play a major role in determining the effectiveness of a retrofit, and this "effectiveness" changes at different stakeholder levels. However, not all retrofits that reduce emissions make economic sense and vice versa when life cycle thinking comes into play. The findings will be useful for building owners and occupants as well as for policy developers and other decision makers interested in demand side management. [ABSTRACT FROM AUTHOR]