The full name for the EEWH-RN system is called “EEWH Evaluation Manual IV: EEWH-RN (Renovation)”. It is the fourth complete system in Taiwan’s “Green Building Family” developed after EEWH-EC for ecological communities and EEWH-GF for green factories. The EEWH-BC green building evaluation system has been very effective in meeting the objective of energy and carbon saving for new buildings but was still deficient in two aspects. Firstly, it does not cover large-scale old buildings, which may be turned green with some updates. Secondly, a mechanism for verifying the performance of green buildings was missing. To achieve the goal of sustainable global and regional development and CO2 reduction, EEWH-RN has been designed specifically for the renovation of existing buildings. It is hoped that by improving the environmental performance of large-scale existing buildings, existing buildings may be updated to become more ecological, energy-saving, waste-reducing and healthy toward the sustainable development of ecological cities.