Integrating life cycle sustainability assessment into building renovation strategies

• A comprehensive LCSA framework that evaluates renovation strategies from a life cycle perspective • MOO of carbon footprint, direct global cost and thermal discomfort • Integration of climate change into the framework, to assess impacts of future climate conditions on the choice of renovations • Case study on a poorly insulated individual house; forecast for the French context • Optimal renovations replace gas systems; envelope insulation strategies vary. This study presents a multi-objective optimization methodology for building renovation, integrating a holistic and prospective approach. The methodology incorporates thermal discomfort into the Life Cycle Sustainability Assessment, addressing a critical gap in existing approaches that undermine the effects of climate change. The methodology involves using Building Dynamic Energy Simulation to quantify energy consumption and thermal discomfort, Life Cycle Assessment for environmental impacts, and Life Cycle Cost analysis for economic evaluation. The study integrates Pareto-optimal strategies and multi-criteria clustering to identify archetypes of optimal renovation strategies which represent a trade-off between environmental (carbon footprint), economic (direct global cost) and comfort (thermal discomfort) objectives. A case study on a French residential building explores over 11,000 renovation strategies under varying climate zones and initial energy systems. In all configurations, carbon footprint and direct global cost values for optimal renovation strategies are not widely dispersed around median values, with relative dispersions inferior to 0.32. However, thermal discomfort following optimal renovations is strongly dependent on climate zone, with a relative dispersion of 1.15 in the context of a warm French climate (H3). 4 to 5 clusters of optimal renovation strategies have been identified for every configuration, highlighting the possible trade-offs between the 3 objectives. Gas-based systems are consistently replaced by thermodynamic solutions, whereas the type and performance of envelope insulation differ across clusters. In all configurations, the majority of optimal renovation strategies include solar protections (56–62%), while cooling systems are implemented less frequently, appearing in only 20–38% of cases.