According to Rakheja, green roofs in hot, tropical climates can be more cost effective than those in colder and more extreme climates. Anand emphasizes the need to select the ideal green roof according to the general climatic condition of the location. For instance, the western states of India may see torrential rainfall for at least a quarter of the year. In such cases, the green roof must be designed to ensure that water doesn't collect on top, instead being immediately drained out preventing stagnation or seepage. Similarly, Rakheja cautions about the possibility of soil erosion in such turfs on sloping roofs.

The Big Picture

According to India's 2011 census, urbanization in India is expected to touch 40% of the population by 2021, and planning authorities have earmarked 533 infrastructure projects worth about $11.1 billion (Rs 60,544.73 crore) to meet the demand. With the estimated increase in urbanization, more green roofs in the sky are likely on the way.

Quick Stats: Green Roofs in India

• Initial cost of laying a green roof: $1—$1.50 (Rs 60 to 80) per sq ft
• Energy savings vs. a conventional roof: 10-30%
• Life of roof fabric: Extended up to 70%

(Source: CII-Godrej GBC)