Heat Where It Hurts - Spatiotemporal weighting for efficient heat impact assessment in Vienna

Abstract

The increasing Urban Heat Island (UHI) effect in Vienna requires targeted mitigation strategies to decrease populations exposure to outdoor heat stress. Traditional models, such as Eulerian Outdoor Thermal Comfort (OTC) assessments, often overlook spatial and temporal variations in pedestrian presence, while complex multi-agent systems require detailed input data that is rarely available at the neighborhood scale. This study presents an efficient spatiotemporal weighting approach that integrates urban microclimate simulations with proxy-based pedestrian density estimations derived from open data sources. Applied to two case study areas in Vienna, the method identifies priority zones for intervention by combining thermal discomfort levels with human occupancy likelihood. Results highlight critical hotspots, particularly at transit stops, where mitigation efforts can have the greatest impact. A scenario involving strategically placed trees and water misting systems demonstrated a reduction in mean weighted thermal discomfort by up to 20%. The proposed method offers urban planners a scalable, data-efficient tool for designing context-sensitive heat mitigation strategies in cities facing rising climate-related risks.