Energy Consumption of Secondary Water Supply System in Typical Old Residential Quarters in Shanghai under the Background of "Double Carbon"

Taking the water supply of mid-rise buildings and high-rise buildings in typical old residential areas in Shanghai as the research object, this paper analyzes and compares the water flow, energy consumption and efficiency of secondary water supply pumps under different working conditions. The water supply flow in the main period of the day in the cistern+variable frequency pump mode is much lower than the rated flow, therefore, under the condition of meeting the same water supply target, the operating efficiency of the cistern+variable frequency pump is about 50% of that in the cistern+main frequency pump+water tank mode. However, some water tanks are too close to the top floor residents to meet the water supply pressure demand only by gravity flow. The cistern+main frequency pump+water tank mode needs to be repressurized, and the repressurization energy consumption of the roof water pump is about 200% of the energy consumption of the variable frequency pump in the pump station. At this time, the energy consumption of the cistern+variable frequency pump mode is lower.