Operational Carbon Impacts of Fabric Retrofits in Victorian Housing: An Assessment Under Future Climate Scenarios

The UK’s housing stock is among the oldest and least energy-efficient in Europe, with most homes built before the introduction of energy regulations in the 1990s. Improving their performance is therefore important for meeting national net-zero targets. While insulation, airtightness and glazing can substantially reduce heating demand, their long-term performance under future climate conditions remains less well understood, particularly when overheating and cooling demand are considered. This study evaluated the long-term operational carbon and thermal performance of five retrofit strategies applied to a typical mid-terrace Victorian house. Dynamic thermal simulations were undertaken for shaded and unshaded models using current and future weather files, with mechanical cooling introduced where overheating thresholds were exceeded. The results showed that deeper fabric retrofit substantially reduced heating-related emissions, with the most comprehensive strategy reducing them by approximately 80.7% relative to the base case. However, highly insulated and airtight configurations also increased summertime overheating and cooling demand. By 2080, cooling demand in the most advanced retrofit scenario became comparable to heating demand. External shading reduced cooling-related emissions by approximately 13-25% across the retrofit scenarios, although its effect on total operational carbon was more modest. Cooling setpoint assumptions also had a strong influence. Overall, the findings show that future retrofit performance should be assessed not only in terms of winter heating reductions, but also in relation to overheating risk, passive solar control and future cooling demand.