# Why are we not able to see the shift in chiller electricity load when we are installing a thermal storage system which can be used to meet the cooling requirements of the given space?

We are modelling a district cooling system with thermal storage. We plan to do this modelling for an entire residential building but are currently doing it for a shoebox model for better understanding of the system functioning. The size of the shoebox model is 400 sqm and there is only one zone group. The cooling operation schedule is from 20:00 to 23:00 everyday.

We are using a FCU(4 pipe) Water cooled chiller, water side economiser type of chiller. The set point temperature of the zone is 20 C. Based on these values, we are trying to design a thermal storage system in order to reduce the peak demand. The thermal storage system was calculated by using the formula: q = mCpdelta T. The thermal storage capacity thus comes out to be around 50KW. The charging schedule for the thermal storage system 03:00- 07:00 with 6.670’C as water setpoint. The size of the thermal storage tank is 50, charging time is 3 hours.

When we are simulating with the above specifications, we are not able to see the shift in load from the normal case when only the chiller is used and the second case, when the thermal storage is integrated, with thermal storage use given 1st priority.

Question: Why are we not able to see the shift in chiller electricity load when we are installing a thermal storage system which can be used to meet the cooling requirements of the given space?

Screenshots of the simulation are in the below link.

https://iiitaphyd-my.sharepoint.com/:...

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