ALREADY acknowledged as one of the leaders in environmentally-friendly construction, India could surpass the United States within four years to become the country with the most space covered by 'green buildings', according to the agency that sets standards and certifies eco-friendly realestate development. The Indian Green Building Council (IGBC), which today has about 110 million sq ft of green real estate registered with it, is targeting a nearly ten-fold increase in eco-friendly property development to a billion sq ft, the council's chairman Prem C Jain said.