Client: Chicago Department of Aviation

Location: Chicago, IL

The Heating and Refrigeration (H&R) Building at O’Hare International Airport is responsible for heating and cooling all airport terminals and buildings. There were nine chillers in the previous H&R Building that had been in service since the 1960s. This project increased the energy efficiency of the cooling system by installing energy efficient chillers with increased capacity, as well as installing new control panels and modulating valves to further improve chiller operation. The project also upgraded both the chilled water and condensed water circulation pumps, and it expanded the system’s cooling tower with more efficient equipment.
The electrical upgrades included replacing five of the legacy chillers with four new chillers designed to be driven by four new medium voltage variable frequency drives (MV-VFDs). An additional 10 new MV-VFDs were installed to control ten new chilled water pumps, replacing constant speed starters on the existing pumps. Four new condenser water pumps with MV-VFDs were also installed to control pumping capacity. New low-voltage power sources were installed for the new chiller control panels, as were new control valves at all eight chillers in the upgraded system.
To accommodate the new chiller capacity, the South Cooling Tower needed to be expanded. This was accomplished by activating two unused bays with new fans with two new low voltage variable frequency drives, new tower controls and well as increasing the size of the motors on four existing fans. Due to the critical nature of the cooling systems, design intentionally split the loads for similar systems onto different utility sources. Separating the electrical loads ensures that in the event of a failure of once source, there will still be operational chilling, condensing, pumping, and chilled water pumps as well as cooling towers.