Bengaluru researchers identify optimal park size to combat urban heat

Researchers Arpit Verma and Sonam Agrawal found that urban parks in Bengaluru, India, create cooling effects that extend beyond their physical boundaries.

The pair published their findings in Advances in Space Research after analyzing 15 urban green spaces using satellite images from both summer and winter seasons. The study showed that most parks reduced surface temperatures by more than 1°C in their immediate surroundings, even in areas where buildings and roads occupied more than 70% of the land.

These cooling effects typically reached between 186 and 246 metres past the park limits, with the impact becoming more pronounced during the summer months. Vegetation helps achieve this by blocking direct sunlight and releasing moisture into the air, which counters the urban heat island effect caused by heat-absorbing asphalt and concrete. The researchers identified specific size benchmarks to help city planners maximize cooling intensity.

They determined that 2.49 hectares, or about 6.15 acres, is an efficient size for reducing surrounding surface temperatures. For those aiming to cool a larger surrounding area, the researchers suggested a size of 5.29 hectares, which is roughly 13 acres. While these figures serve as planning benchmarks rather than strict rules, they provide a framework for developing neighborhood greenery in densely built areas. The researchers noted that these measurements reflect land surface temperatures rather than the air temperature people feel.

The findings suggest that protecting existing parks and strategically planning new green spaces can help Bengaluru maintain its identity as a Garden City while mitigating rising temperatures in crowded neighborhoods.