Economic Efficiency Study Of CWS System For Existing Buildings

China is growing continuously and power requirement is arising year by year.The government has developed a large amount of power plants to deal with thepower shortage, but now power shortage among seasons and hours appears.Meanwhile power consumption of HVAC system in existing buildings aggravatesthe power shortage on peak hours. Chilled water storage is a preferred demand sidetechnology for shifting cooling load demand from peak hour to off-peak hour andsaving electric cost for consumers. The paper has studied the operation mode,selection of storage capacity and the effect of chiller performance, tank performanceand some other factors on the economic efficiency of CWS renovation project.The paper has adopted eQuest to simulate the energy consumption of anexisting building to get credible hourly cooling load and established a mathematicalmodel of hourly energy consumption and expense. The model includesmeteorological parameter, building load characteristic and some other factors. Thepaper provides calculation program of MATLAB to calculate operation fee, shiftingelectric quantity, payback and NPV quantificationally and serves preferred coolingstorage capacity. The more important factor for economic efficiency in sequence isCOP, discharging limit, FOM.For some public buildings in north, the utilization rate of CWS is not very high.So the payback and NPV of renovation project is sensitive to the initial cost andelectric charge. The government should optimize the hourly electric charge,enhances the peak hour charge and lowers the off-peak hour charge to extend thedifference between them and supplies some other awarding measures to impel CWSrenovation project for existing buildings.