This project is to develop deep learning technology to enhance the building energy efficiency. The new technology can decide the optimal control policy based on the operational data on the integrated building system including smart-grid, air conditioning and mechanical ventilation (ACMV), solar, lighting and occupancy. It has the benefits of energy efficiency optimization, adaptation to equipment and operation conditions and robustness against environmental uncertainty, compared with the current state-of-the-art of model-based control, which highly depends on detailed domain knowledge and many restrictive assumptions. The final target is to achieve 20% energy saving and higher comfort level. The technology can be promoted island wide through a parallel AI cloud with great significance on energy sustainability and service quality.