Impact of landscape design with nature-based solutions on summertime microclimate conditions: a field measurement study

Extreme heat events increasingly threaten urban microclimates, intensifying public concerns about outdoor thermal comfort. While urban overheating has been extensively studied in hot regions, empirical evidence for cold-climate cities during overheating periods remains limited. This study investigates how vegetation density, surface albedo, and building morphology influence local microclimate conditions and outdoor comfort in a representative office campus in Ottawa, Canada. Using both fixed and mobile weather stations, we measured air temperature, relative humidity, wind speed, solar radiation, and surface albedo across diverse landscape settings, including parking lots, building facades, lawns, tree canopies, and residential backyards. On heatwave days, areas with dense tree coverage reduced peak air temperatures by up to 8 °C compared to paved zones, demonstrating the combined cooling effects of shading and evapotranspiration. Conversely, paved surfaces, building walls, and industrial facilities exhibited higher daytime temperatures due to heat storage and limited ventilation. Even small-scale greenery, such as residential backyards, moderated daytime heat and enhanced nighttime cooling, highlighting the role of vegetation in improving diurnal microclimate balance. These findings provide quantitative evidence supporting the integration of green infrastructure, reflective materials, and optimized urban morphology into planning practices for heat mitigation. By demonstrating how localized design interventions influence microclimate patterns, this study contributes to climate-resilient urban design strategies for cold-climate cities facing intensifying summer heat extremes.