Cities typically use more electricity than rural areas, primarily due to the “urban heat island” effect. The buildings and other structures in cities trap and emit heat, making them warmer than neighbouring areas and forcing them to consume more power.
For instance, Delhi’s electricity consumption rises an extra 11%, or 2,600 gigawatt-hours a year, just because of the urban heat island effect, a new study finds. In monetary terms, this is an excess ₹1,400 crore spent every year.
To calculate the heat island effect, the study’s authors, led by Priyanka Kumari of Jawaharlal Nehru University, analyze eight districts of Delhi from 2012 to 2017. Satellite data is used to see how much more a district’s land-surface temperature is than that of neighbouring rural areas.
The northwestern part of Delhi has the weakest heat island effect in a year, gaining 3.5 degrees Celsius in the summer, compared to 6.2 degrees for Central Delhi. This is because the northwestern part is the least urbanized, with more agricultural area. For all districts, the heat island effect is the weakest during monsoons and greatest during spring.
While the heat island effect makes the spring and summer worse in Delhi, making people use air conditioners more and consume more power, it saves electricity in the winter, when temperatures aren’t as low as they could be, so people use heaters less and consume less power.
The extra ₹1,400 crore spent on electricity every year because of the heat island effect is in a way the cost of urbanization for society. The authors suggest measures such as cool roofs, heat-reflecting high-albedo surfaces and more green spaces, which they say can help reduce the urban heat island effect and bring down this extra spending.
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