Major Indian metros ranked below avg in Asian Green City Index

According to the study, Pakistan's commercial capital Karachi was the worst performer, being alone in the list of cities "well below average." In the index of 22 cities, Mumbai, Kolkata and Bengaluru find themselves with Manila, capital of the Philippines, and Vietnamese capital Hanoi.

The research commissioned a few months back by German engineering major Siemens and Economist Intelligence Unit categorises, Asian cities with respect to the environmental performance in eight categories: energy and CO2, land use and buildings, transport, waste, water, sanitation, air quality and environmental governance.

It said "well above average" Singapore City "stands out in particular for its ambitious environmental targets and its efficient approach to achieving them." The Indian capital is among "above average" performers in Energy management and curbing CO2 emissions, but Kolkata disappoints with a below average tag. Each inhabitant in Delhi generates, on average, an estimated 1.1 tonnes of CO2 per year, the third best level in the Index, and well below the Index average of 4.6 tonnes.

The report lauded Delhi and said it "has proactive policies to limit greenhouse gases. It also scores particularly well for its climate change action plan." Even Mumbai had better reading with its inhabitants emitting an estimated 1 tonne of CO2 per capita per year, which is much lower than the Index average.

Giving example of Delhi's environmental governance, the report said "City's environmental department is using school 'eco-clubs' to try to shape student's views: Students can engage in a vast range of activities, including air monitoring, water harvesting, eco-tours, and awareness-raising campaigns...Convenient way to spread information widely on environmental campaigns."

Kolkata is one of the better performers on the water front with consumption of 138 litres per person per day. This is one of the best rates among the 22 cities, and better than the average of 278 litres.

Mumbai is also competing with Kolkata on water front. The report said the western metropolis has "fairly efficient water system," losing just 14 per cent of its water flow through leaks versus the Index average of 22 per cent.

This is one of the best rate among cities. The study lauds the recent official efforts to reduce water leakages, which once ran as high as 50 per cent. Mumbai is also comparatively sparing in its water use, consuming on average 250 litres per capita per day.

"Other Asian cities as well, environmental awareness and climate protection guidelines are playing an increasingly important role," the company said in a statement. Delhi stands in average category along with Shanghai, Bangkok, Beijing and other rising Asian cities Guangzhou, Jakarta, Kuala Lumpur, Nanjing and Wuhan.

Cities which performed better than the Indian Capital were Hong Kong, Taipei, Osaka, Tokyo, Seoul and Yokohama.