How can cities, especially those in developing countries, become more energy-efficient and sustainable? The recent World Cities Summit in Singapore brought no easy answers.

Dr. Isher Judge Ahluwalia from India highlighted during the conference’s keynote plenary that her country needs to pump in some $400 billion in the next two decades to improve its urban infrastructure including public transport, roads and sanitation.

“Some of the cities in India are ready to join the industrial world in [terms of] consumption standards but many of us are still dealing with the margins of existence,” said the chairperson of Indian Council for Research for International Economic Relations.

While Indian cities struggle to deal with slums and catch up on their infrastructure deficit,