# huge condenser water pump saving because of more chillers

I am trying to study the influence of chiller number on building energy consumption and found the most significant difference is the condenser loop pump! Two simple cases were simulated using OS1.7 (link: 1 Chiller, 2 Chillers)

All the plant loops are autosized and all the equipment performances are the same. The only difference is that first case has 1 chiller with sizing factor of 1, the other case has 2 chillers and each of them with sizing factor of 0.5. Results show that the second case pump energy is only 1/3 of the first case which is mainly resulted from condenser water pump. Anyone knows how to explain the results?