Urban building designs trap heat and slow ground-level winds across Indian cities

UPDATE - follow-up to Letting the wind flow freely is the secret to cooling our cities: Ground-level wind speeds in Indian metropolitan areas continue to drop as taller buildings and dense urban structures disrupt natural air flow, intensifying humidity and heat stress for pedestrians. Wind speeds near the ground have been falling worldwide in a trend known as terrestrial stilling since the 1980s.

Urban Design Factors

Amruthraj M.N., a consultant with the Sustainable Energy Lab at the Indian Institute for Human Settlements in Bengaluru, notes that reduced wind speeds typically occur around 10 meters from the floor where pedestrians walk. Dense infrastructure, high compound walls, and podiums block wind corridors, while the replacement of vegetation with asphalt and concrete increases surface friction and reduces evapotranspiration. Meteorologist Aaron Serre from the University of Alabama in Huntsville explains that high-rise buildings create turbulence and trap heat.

Air Flow Effects

When tall buildings interrupt wind flow, air can be forced through narrow spaces in the Venturi effect, creating sudden gusts, or driven downward in a downdraught effect. Prasad Vaidya, senior adviser at IIHS, states that unplanned higher building forms directly contribute to lower wind speeds and additional heat stress, which also slows down the dispersal of air pollution. Yugank Goyal, associate professor at IIM Ahmedabad, highlights the need for a homogenised wind record using consistent anemometer placement and satellite imagery to map city ventilation.

Context

Urban planning rarely incorporates computer simulations like computational fluid dynamics due to high costs and technical demands, though cities like Stuttgart, Seoul, and Hong Kong use them to improve ventilation. Understanding how buildings shape local wind patterns remains a key step for managing urban heat stress and air quality.