Urban building designs trap heat by blocking vital ground-level winds

UPDATE - follow-up to Letting the wind flow freely is the secret to cooling our cities: Ground-level wind speeds in cities continue to drop due to terrestrial stilling and dense high-rise construction, worsening urban heat stress.

Urban Wind Barriers

India's metropolitan cities face reduced wind speeds near the surface, typically around 10 meters from the floor where pedestrians walk, due to dense urban infrastructure and high-rise buildings. Amruthraj M.N., a consultant at the Indian Institute for Human Settlements in Bengaluru, notes that structures like high compound walls and podiums restrict wind flow. Aaron Serre, a meteorologist from the University of Alabama in Huntsville, explains that replacing vegetation with asphalt and concrete also reduces evapotranspiration and intensifies the urban heat island effect.

Airflow Effects

When tall buildings interrupt wind flow, the wind can funnel through narrow spaces to create gusts in the Venturi effect, or slam into structures to push downwards in the downdraught effect. Prasad Vaidya, a senior adviser at IIHS, states that unplanned higher building forms contribute to lower wind speeds and extra heat stress, while also slowing down the dispersal of air pollution. Experts suggest using satellite imagery and computational fluid dynamics simulations to map city ventilation, though such models remain expensive to implement.

Context

Terrestrial stilling is a global phenomenon where near-surface wind speeds have been dropping since the 1980s. Understanding how urban geometries affect local microclimates helps city planners design better spaces for pedestrian comfort and public health.