This study investigates the impact of heatwaves on the thermal comfort and well-being of elderly individuals living alone during heatwaves, focusing on two contrasting residential typologies in the Atlantic climate of Spain: a dense urban area and low-density peri-urban setting. A mixed-methods approach was used, combining in situ environmental monitoring, adaptive comfort modelling, and user-centred data from surveys and interviews based on the De Jong-Gierveld Loneliness Scale. The results show that both dwellings exceeded recommended indoor temperature thresholds during heatwaves, especially at night, contributing to sleep disturbance, cardiovascular stress, and emotional discomfort. Despite 85% of participants indicating that outdoor activities help them to mitigate not-wanted loneliness, architectural barriers often hinder such engagement. Over half reported having no balcony or terrace, which may have further intensified social isolation. Field data collected during 2022 summer heatwaves recorded maximum daytime temperatures of 30 °C and night-time peaks of 28.7 °C, exceeding the 25 °C threshold. The adaptive comfort evaluation classified both cases as Class 4 (severe discomfort). The urban dwelling showed consistent moderate discomfort (Category 3), likely due to poor ventilation and urban heat island effects. The peri-urban case, despite lacking the heat island influence, showed worse thermal conditions, especially during the day. Architectural barriers, poor thermal performance, and the lack of semi-outdoor spaces may exacerbate isolation among elderly people during extreme heat events.

Outdoor environmental comfort is increasingly relevant amid climate change and population ageing because it affects well-being, behaviour and public-space use. However, the relationship between microclimatic conditions, environmental perception, and public-space use among older adults remains underexplored. The novelty of this study lies in integrating environmental measurements, subjective thermal perception, microclimatic simulations and public-space use within a baseline assessment undertaken before the redevelopment of a real public space, providing an evidence-informed framework for age-friendly urban design. The study examines environmental conditions, subjective perception and reported public-space use among adults aged 55 years and over within the Barrendain intervention area (Beasain, Spain). A mixed-method approach combined seasonal field surveys (n = 117) with microclimatic simulations. Survey data included thermal sensation, environmental perception, adaptive behaviour, and reported public-space use and perceived sociability. PET distributions were simulated using ENVI-met/BIO-met simulations driven by meteorological data from an official weather station. The results indicate that thermal perception exhibited a marked adaptive character. Neutral temperatures ranged from 12.35 °C in the cold-period campaign to 19.87 °C in the warm-period campaign, reflecting seasonal adaptive thermal responses among older adults. Tree-covered areas presented lower PET values than exposed surfaces during warmer conditions, highlighting the role of vegetation in mitigating summer heat stress. The partial correspondence between simulation-derived PET and subjective thermal sensation further emphasises the importance of combining objective microclimatic assessment with user-centred evaluation in age-friendly public-space design. In addition, 55% of respondents reported using the intervention area primarily for physical activity, whereas 36% identified social encounters as a main motivation for visiting the public space. The findings indicate that environmental comfort should be understood as an enabling condition for public-space use and perceived sociability rather than as their sole determinant. The proposed methodological framework demonstrates how simulation-based and user-centred evidence can be combined to support climate-responsive and age-friendly urban regeneration.