This document provides an overview of the Green Rating for Integrated Habitat Assessment (GRIHA) rating system for existing buildings in India. It discusses the importance of green buildings and sustainable construction given growing resource constraints. The GRIHA rating system aims to assess and improve the environmental performance and indoor comfort of existing buildings. It is a 100-point system consisting of 12 criteria across 7 categories, including site parameters, maintenance, energy, water, health, social aspects, and bonus points. 6 criteria are mandatory for certification. The document then outlines the GRIHA rating process and provides details on the criteria and point distribution. It aims to promote sustainable solutions for existing buildings that reduce costs and environmental impacts.