An Integrated 3D Survey–Simulation–VR Approach for Microclimate and Heat-Stress Assessment in Historic Centres: Application to the Ponte Vecchio Area (Florence, Italy)

Urban heat islands (UHI), intensified by global warming, are an increasingly critical environmental and public health issue. In high-value historic centres, dense urbanisation and large summer tourist flows can further increase heat-stress exposure. In this context, digitalisation and Virtual reality (VR) offer promising ways to interpret UHI patterns and support mitigation planning. However, assessing urban microclimate and heat stress in historic areas remains challenging because complex morphologies, narrow street canyons, visual occlusions, and regulatory constraints limit conventional UAV-based survey strategies. At the same time, end-to-end workflows integrating point-cloud reality capture, microclimate simulation, and VR-based visualisation remain underrepresented. This paper investigates how integrated survey-based documentation and environmental simulation can support the diagnosis and conservation-oriented management of climate stress in historic built heritage. The proposed four-step survey-to-simulation workflow integrates 3D survey documentation, on-site inspections, climatic datasets, microclimate simulation, and VR-based visualisation. Applied to the Ponte Vecchio area in Florence, the simulations show present-day peak air temperatures of about 35.6°C at pedestrian level, with UTCI values exceeding 46°C in sun-exposed areas. Under the 2080 scenario, maximum air temperatures reach about 39.6°C, and UTCI values reach the extreme heat-stress category. These heat-stress patterns are visualised in VR, facilitating spatial interpretation within the historic context.