Development of an evidence-based methodological framework for overheating risk assessment of higher education buildings: occupant-centric retrofitting design strategies

This study investigates overheating and indoor air quality in an eight-storey, atrium-type higher-education building in London. High glazing ratios and dense occupancy were hypothesised to assess overheating risk and CO 2 concentrations. A mixed-methods framework combined 10-minute environmental monitoring between July 2024 and April 2025 with a calibrated building energy simulation model. Thermal comfort was assessed using TM59 and EN 16798, and IAQ via BB101 thresholds; field data informed schedules, gains, and ventilation for model calibration. Summer indoor temperatures peaked at 30 °C; mean daily maxima and minima were at 24.69 °C (SD 2.57) and 22.56 °C. Across 120 occupied hours, 5.0 % (6 h) were > 28 °C (TM59 limit: 3 %), while DWE remained ≤ 6. Winter–spring studios met TM59 (0 % hours > 28 °C; DWE = 0). CO 2 levels typically ranged 900–1,300 ppm, consistently < 1,500 ppm but frequently above a 1,000 ppm “good” target. The study findings indicate that solar gains and internal loads as primary drivers. Recommended measures are external shading, controlled night-purge, timed pre-class/break purges, CO 2 -based demand-controlled ventilation (900–1,000 ppm setpoint), internal gain reduction, and targeted peak-shaving mechanical cooling, prioritised and validated through calibrated evidence-based retrofit design strategies for TM59/BB101 compliance.