Abstract: In order to reduce the booming air-conditioning energy consumption in Yancheng, a basic model was established in Yancheng with the most widely distributed 6-story unit dwellings, and the space design elements and thermal design elements for the envelope that affected the energy consumption for heating and cooling were analyzed by EnergyPlus8.7. The simulation results showed that the energy saving effect of the southward sunlight room decreased with the increase of the depth of the sunlight room. The maximum energy-saving rate could be 6.62%. The energy saving effect of the northward buffer space increased with the increase of the depth, which could save energy by 13.44%. It would be the best mothod for energy-saving to add EPS insulation boards outside north walls or roofs, the energy-saving effect would fall down if EPS boards would be installed outside sowth walls, and it would almost be useless to install EPS boards outside esat and west walls. Adding 40 mm thick EPS insulation boards to the north wall, roof and south wall could save energy by 9.39%, 10.33% and 4.24% respectively. The energy-saving model after the transformation of the space organization and the envelope structure was 44.07% more energy efficient than the basic model.