Strategies for reducing overheating in residential buildings: a comparison of shading systems in a temperate climate – a case study of Poznań

The rising demand for building cooling underscores the need to evaluate passive thermal strategies that limit solar heat gain while maintaining acceptable indoor conditions for occupants. This study assesses residential shading systems in a dual-chamber experiment in Poznań, Poland (August 2024), comparing fully and partially deployed external roller blinds, internal roller blinds, and fixed eaves. Fully lowered external blinds stabilised indoor temperatures around 26.5–27.0°C with about ±1.0°C spatial variation and produced the largest reductions, including notable attenuation of near-window temperature peaks. Half-lowered external blinds retained most of the thermal benefit relative to full closure while still admitting daylight, suggesting a practical compromise between cooling performance and perceived space quality. Internal “day/night” blinds provided moderate reductions compared to unshaded conditions but typically maintained indoor air about 1°C warmer than with external blinds, reflecting lower heat-gain mitigation. Fixed eaves sized to half the window height had minimal impact on average indoor temperature and were strongly constrained by solar geometry and orientation. Overall, the results establish comparative performance baselines for indoor air temperature and support layered, context-specific shading strategies deploying external blinds where peak mitigation is critical, partial deployment when some daylight admission is desired, and internal blinds for cost-effective flexibility in controlling solar gains.