Multi-Scale and Multi-Indicator Environmental Accounting of Lifestyle-Related Consumption

Lifestyle-related consumption accounts for a large share of global greenhouse gas (GHG) emissions. Yet, it remains only partially addressed by production-based inventories and is rarely operationalised at sub-national scales. This doctoral thesis develops and applies a consumption-based, multi-scale environmental accounting framework to quantify the climate and resource implications of everyday lifestyles, using Italy as a national case study and Tuscany as a sub-national application. At the national level, the research estimates the carbon footprint of the average Italian lifestyle across four core domains—nutrition, housing, mobility, and expenditures on goods and services—using a hybrid bottom-up approach grounded in life cycle assessment (LCA). Consumption is primarily expressed in physical units (e.g., kilograms of food, passenger-kilometres, kilowatt-hours), improving transparency and facilitating the linkage between quantified impacts and concrete mitigation actions. The results indicate an average lifestyle carbon footprint of approximately 8.3 t CO₂e per capita per year, with food, housing, and personal mobility representing the dominant contributors. Building on this baseline, the thesis evaluates a set of lifestyle-oriented emission-reduction policies and integrates them into progressively more ambitious decarbonisation scenarios. The most effective mitigation options are found in the nutrition and mobility domains, where dietary shifts and modal changes yield per-capita reductions on the order of several hundred kilograms of CO₂e per year. When aggregated across domains, the scenarios achieve substantial emission reductions relative to the baseline; however, even under optimistic assumptions (excluding rebound effects), current lifestyles do not align with stringent climate targets. To contextualise these results within global climate constraints, the analysis integrates a carbon budgeting framework based on an equal per-capita allocation of the remaining global carbon budget. Under a 1.5 °C target with limited reliance on end-of- century negative emissions, the resulting lifestyle-related carbon budget for Italy is approximately 1.9 t CO₂e per capita per year by 2030, corresponding to a reduction requirement exceeding 75% relative to current lifestyle emissions. Alternative assumptions regarding mitigation timing and negative emissions relax this constraint, illustrating how global scenario choices directly affect perceived national and individual mitigation efforts. The methodological framework is subsequently downscaled to the regional level for Tuscany, enabling a direct comparison between national and sub-national lifestyle emissions. The regional results reveal deviations from the national average driven mainly by differences in mobility behaviour, housing characteristics, and expenditure patterns. While regionalisation enhances the relevance of the results for local policy design, it also exposes methodological challenges related to data availability, statistical representativeness, and the use of uniform emission factors across spatial scales. In addition to climate impacts, the thesis applies Emergy accounting as a complementary indicator to assess the cumulative resource use embedded in Italian lifestyles. Expressed in solar emergy units (sej), the Emergy results display domain rankings that differ from those obtained through carbon footprint analysis, indicating that consumption patterns may differ under different lenses of evaluation. The joint use of carbon footprint and Emergy indicators highlights trade-offs between decarbonisation and broader resource dependence that are not captured by single- indicator assessments.