Residential building heating plays a critical role in building energy conservation in China as it consumes a large proportion of the total primary energy use. Heating energy consumption in China is much larger than that in leading countries. This study investigated the energy saving potential from the building envelope design and actual operation optimization. Results showed that the heating energy consumption target specified in latest forth-step energy efficiency standard in Tianjin still leads to 30.9% higher energy consumption than German building energy efficiency standard EnEv'2009 and 49.7% higher than Passivhaus standard used in Germany. Via field measurement and questionnaire survey during operation, major findings are: (1) high indoor air temperature and window opening for ventilation are accountable for the high heating energy consumption during the operation; (2) radiator heating consumes less energy than radiant floor heating system; (3) temperature-type thermostatic valve and compartment automatic control mode have the best control performance; (4) ventilation device with purifying air unit helps to improve the indoor air quality in the terrible haze weather and to reduce the window opening demand of occupants; (5) heat metering and occupants' energy saving awareness should be encouraged.