When undergoing the process of retro-commissioning (RCx), Three Garden Road achieved energy saving with aid of smart technology in addition to typical measures. A Demand Control Ventilation in carpark with IoT sensors is applied to measure indoor air quality and ensure sufficient ventilation within the area. Real-time data can then be transmitted to the BMS system. With the carpark ventilation fans upgraded with variable speed drive (VSD), the speed can be adjusted automatically according to the actual exhaust loading inside the carpark. Hence, a healthy indoor air quality can be maintained while a significant amount of electricity is conserved.
Control optimisation by chilled water by-pass valve reset and chilled water supply temperature reset further contributed to this remarkable saving of energy. As rated flow is provided to chiller at all time, chilled water by-pass valve always opens and hence cause energy inefficiency. The chilled water by-pass valve control reset strategy is optimised by reset the by-pass differential pressure of header to provide appropriate amount of flow to chillers. After this modification, the overall chiller plant COP is improved by 8.9% annually. Moreover, a new control logic of resetting set point of chilled water supply temperature according to outdoor temperature was applied for further energy saving. Three Garden Road has demonstrated an outstanding application of smart technology in the building to pursuing energy saving without sacrificing the indoor environmental quality and customer’s satisfaction.