TABLE OF CONTENTS - The Professional Green Building Council

Theme B: Creating a livable, healthy and environmentally viable citiesWater-side of an AC system includes mainly the chillers, which consume themajority of energy of the system. The POE team found that proper setting ofchiller on-off could significantly affect the energy consumption. For water-cooledchillers, the electrical energy input, AC cooling energy output and the enteringcondensing water temperature would be recorded from the CCMS for energyprofile analysis. Different types of chillers have different operating efficiency atfull and part load. The coefficient of performance, i.e. the operating efficiency, ofeach chiller would also change significantly under different chiller loading andcondensing water temperature. The control of chiller cut-in/cut-out and operationcombination becomes complex and significant. It could be site specified to suitdifferent cooling load profiles. The important point was for the POE team toaccurately record the actual load profiles at different seasons and to adjust thechiller cut-in/cut-out time. The POE team also found that use of variable speedchillers to meet the AC load requirement was more efficient than the conventionalequal load sharing by all operating chillers.b) SensorsIn the energy and load profile analysis, the accuracy was heavily relying on thedata collected through the CCMS. It was found that the location of sensorsinstalled for collection the required information, such as the water flow of aselected chilled-water pump, had significant impact on the accuracy of the datacollected and hence the final analysis results. The reliability and accuracy of thesesensors also played an important role. The POE team therefore recommendedfuture project teams to allocate more resources on this issue.5. CONCLUSIONAlthough ArchSD has commenced POE exercises for only about 2 years, valuableexperience and knowledge on evaluation of performance of building and buildingservices installations are already being built up. Through these exercises, bettercommunication channels can be built among the designers, the end-users and the536