Abstract: A refrigeration system includes a low temperature portion with a primary loop that circulates a refrigerant to temperature-controlled storage devices operating at a low temperature, the primary loop also including a condenser to at least partially condense the refrigerant. The refrigeration system also includes a medium temperature portion having a primary refrigerant loop and a secondary coolant loop, the primary refrigerant loop provides cooling to the secondary coolant loop through a chiller. The secondary coolant loop has a first branch and a second branch, where the first branch circulates coolant to temperature-controlled storage devices operating at a medium temperature, and the second branch circulates coolant to the condenser of the low temperature portion.