Thermal amplification by large-footprint buildings in cold-climate cities: Implications for urban heat mitigation

The optimal architectural paradigm for human settlements in cold climates remains actively debated, with large-footprint, low-rise buildings often promoted as protection against extreme environmental conditions. However, the broader impact of such developments on urban thermal anomalies in Arctic and sub-Arctic cities remains poorly quantified. This study evaluates the city-scale thermal influence of large low-rise structures classified as Local Climate Zone 8 (LCZ 8) in Fairbanks (USA), Tromsø (Norway), and Nadym (Russia), three high-latitude cities with contrasting urban morphologies. Using Landsat thermal infrared imagery, refined OpenStreetMap building footprints, and GIS-based spatial and statistical analyses, we show that expansive low-rise buildings (>10,000 m² footprint) consistently act as localized summer thermal hotspots. Hotspot intensity and spatial clustering increase systematically with building footprint size and spatial aggregation, with land surface temperatures up to 4°C higher than surrounding urban areas. These anomalies are associated with extensive impervious and dry surfaces, flat roofs, and limited vegetation, which enhance solar absorption and thermal inertia, particularly under weak atmospheric mixing conditions characteristic of cold-climate urban environments. The results challenge conventional urban heat island assumptions by demonstrating that horizontal building scale is a key control on urban thermal behavior in cold regions. Importantly, these findings do not imply that northern cities require heat adaptation strategies derived from warm-climate contexts. Instead, they highlight the need to re-evaluate how localized warming interacts with infrastructure performance, seasonal comfort, and outdoor activity patterns, positioning LCZ 8 districts as priority zones for climate-responsive and seasonally adaptive urban design.