Urban blue-green infrastructure for climate resilience: integrating thermal comfort in Sri Lankan public spaces

This study investigates how urban blue-green infrastructure (BGI), urban systems combining vegetation and water-based elements to enhance ecological performance and thermal comfort. Under ASHRAE Standard 169, Jaffna falls within Climate Zone 0A (Extremely Hot and Humid), making thermal comfort enhancement essential for sustainable urban living. Two key sites, Aariyakulam Lake Trail and Pannai Coastal Promenade, were analysed using empirical field measurements, user surveys, and ENVI-met simulations. Thermal comfort was evaluated through the Predicted Mean Vote (PMV) and Thermal Sensation Vote (TSV) models, supported by on-site climatic data.
Results show that BGI significantly reduces urban heat stress, with the Pannai Coastal Park registering lower PMV and higher Thermal Comfort Vote (TCV) values than Aariyakulam Lake Trail due to its greater vegetation density, coastal proximity, and improved airflow. Users consistently preferred shaded areas, trees, water features, and breezy zones, while prolonged stays correlated strongly with thermally comfortable microclimates, confirming the relationship between design and inclusive social interaction. Empirical and simulated data validate the measurable cooling effects of BGI, demonstrating its effectiveness as a climate adaptation strategy in tropical warm-dry environments. The study develops a contextual framework linking thermal comfort and climate resilience, offering policy recommendations for biodiversity-positive urban design and public space planning in Sri Lanka’s evolving coastal cities.