Urban planning gaps and high-rises worsen near-ground wind drop in Indian cities

UPDATE - follow-up to Letting the wind flow freely is the secret to cooling our cities: Ground-level wind speeds in urban areas continue to face severe disruptions due to dense high-rise construction, poor building spacing, and the replacement of green cover with concrete. Near-surface wind speeds, typically measured around 10 meters from the floor where pedestrians move, have been dropping globally in a trend known as terrestrial stilling since the 1980s.

Urban Factors

Amruthraj M.N., a consultant with the Sustainable Energy Lab at the Indian Institute for Human Settlements in Bengaluru, points out that high compound walls, podiums, and clustered high-rises block designated wind corridors. Aaron Serre, a meteorologist from the University of Alabama in Huntsville, adds that replacing vegetation with asphalt and concrete cuts down evapotranspiration and worsens the urban heat island effect. When wind hits tall buildings, it creates phenomena like the Venturi effect in narrow gaps and downdraughts that force air downward into sudden gusts.

City Planning

Prasad Vaidya, a senior adviser at IIHS, notes that computer-based fluid dynamics simulations show small changes in building shapes can cause eddies that slow air movement. However, these complex computer models remain expensive and are rarely used in routine Indian urban design. Yugank Goyal, associate professor at IIM Ahmedabad, suggests using satellite imagery to map city ventilation and connect those insights to master plans, similar to ventilation assessments done in Stuttgart, Seoul, and Hong Kong.

Context

Terrestrial stilling reduces the natural air movement needed to clear trapped humidity and disperse city pollution. Urban heat islands intensify when concrete and lack of trees combine with blocked wind patterns, making hot days feel much harsher for pedestrians.