To estimate the subjective and objective weights of each index, the entropy weight approach was integrated with the analytic hierarchy process in light of the current issues with building energy conservation and sustainable development. This study found that among four indicators, the proportion of environmental sustainability was 48.19%, which had the most significant impact on the energy-saving potential and sustainable development efficiency of buildings. The weight value of the environmental load capacity index was 0.1104. On this basis, the cloud model was used for qualitative and quantitative analysis, and a comprehensive model based on four first-class indicators was established. The study found that the evaluation value of this index showed a kind of volatility, with a peak of 1 and a maximum frequency of 0.6. Overall, it displayed ‘generic’ and ‘good’ traits, demonstrating that people did not give enough thought to the sustainability of the environment and system while pursuing economic and social sustainability. In conclusion, the evaluation method chosen in this study can solve the fuzziness and randomness better in the efficiency of energy conservation and sustainable development of green buildings. This method has a significant impact on the evaluation of real green buildings.