Sustainability is moving from buzzword to business case. In Jan-Oct 2025, 34% of new residential launches in Navi Mumbai were certified green (IGBC Gold/Platinum or LEED), up from 21% in 2022. Sample projects: Godrej Nest, Marathon Nexworld, Adhiraj Capital City. Premium: 6–8% over conventional inventory. Savings: electricity 18%, water 25%, maintenance ₹1.2/sq-ft lower. Our 10-year NPV model shows green premium breaks even at year-7 for end-users and year-5 for investors if resale premium sustains at 5%. Government push: extra 0.2 FSI and 10% rebate on prop-tax sweeten the deal. Keywords: green homes premium, IGBC rating ROI, sustainable real estate.