The energy consumption,exergy consumption,CO 2 emissions and cost of five public buildings in Hunan area in its life cycle were calculated based on life cycle theory and exergy method,taking into account the formation of building envelope. On this basis,two indicators including the building exergy-energy ratio and greenness were introduced. The greenness of each building was obtained by analytical hierarchy process. The comparison of the greenness indicators shows that office buildings are much better than commercial buildings in terms of greenness. Comprehensive comparison of the two indicators illustrates that there is an optimal range for exergy-energy ratio. The greenness indicator takes into account the building life cycle resources consumption,cost input and environmental impacts,and the exergy-energy ratio demonstrates the use of high quality energy. Therefore,these two indicators can serve as a supplement to the passive energy saving clauses in the existing sustainable building assessment systems.