Service-Based Life Cycle Approach to support Lifetime Extension Strategy of Smartphones: from Repair Incentives to Behavioural Scenarios

Smartphones are associated with significant environmental impacts, largely driven by frequent replacement and short effective lifetimes. Extending device use is therefore often proposed as a key strategy to reduce these impacts. This thesis assesses how alternative smartphone lifetime-extension strategies influence climate-change impacts in the German context. A cohort-based lifetime model is developed to represent heterogeneous device ageing, failure, repair, and replacement behaviour, and is coupled with a life cycle assessment approach using a service-based functional unit defined as one smartphone-year of service. This approach enables environmental impacts to be compared across scenarios based on delivered service rather than on individual devices. Three scenarios are analysed: a baseline reflecting current use patterns, a repair-incentive scenario with increased repair uptake, and behavioural lifetime-extension scenarios in which median device lifetimes are progressively extended. The results show that increasing repair uptake through financial incentives leads to a small reduction in climate-change impacts per smartphone-year. In contrast, behavioural lifetime-extension scenarios yield larger reductions in impacts. Even a moderate increase in median device lifetime reduces the number of new smartphones required per unit of service and leads to a greater decrease in greenhouse-gas emissions. Across all scenarios, the contribution of spare-part replacement remains small relative to the total impact per smartphone-year, with overall results dominated by changes in new device provision. Although the analysis relies on a simplified cohort structure and secondary life-cycle inventory data, the findings indicate that repair incentives are most effective when embedded within a broader behavioural context that promotes longer device retention.