No More Thermostat Wars, Thanks to Central Control

The Northrop Grumman IT dispatch and help desk center in Denver, like most technical support operations, is open around the clock. The 48,000-sq.-ft., single-story building is filled with high-tech data processing and communications equipment, as well as 110 employees. And all of these electronics and people need to be kept at the right temperature.

04/01/2003


The Northrop Grumman IT dispatch and help desk center in Denver, like most technical support operations, is open around the clock. The 48,000-sq.-ft., single-story building is filled with high-tech data processing and communications equipment, as well as 110 employees. And all of these electronics and people need to be kept at the right temperature.

The facility uses 22 rooftop electric cooling/natural gas heating units that were installed as part of the original core shell. These constant-air-volume, single-zone units are each equipped with thermostat controls. Northrop Grumman has also added three 20-ton computer room air-conditioning (CRAC) units to cool critical equipment.

When it comes to temperature settings, 110 employees means 110 different comfort levels. Facility managers soon learned that many employees preferred to periodically adjust the thermostat in their work areas, which led not only to frequent arguments, but also inefficient HVAC system operation.

Additionally, Performance Building Services (PBS), a Denver mechanical engineering and contracting firm with an intimate knowledge of the facility's HVAC system, warned that by using the original thermostatic controls, portions of the HVAC system could fail, potentially damaging electronic equipment and threatening stored data.

Facility manager David Chansilp wanted a system that would not require thermostats and would allow temperatures to be set from a single location, but at the same time, could monitor equipment and sound an alarm in the event of equipment failure. And, it would need to be installed with minimal disruption to a facility that's open all the time.

"When you have a situation like that," Chansilp says, "it forces you to go to an area to determine what the temperature is, what the environment is, and make your adjustments. Then, you have to move on to the next area to determine what to do, whether you must increase or decrease your setpoints. That's a big pain."

Northrop Grumman chose an integrated control system to cover the HVAC system and provide monitoring and remote alarming for air-conditioning units in essential computer rooms. A controller is assigned to each rooftop and is responsible for monitoring and controlling the supply fan and monitoring the discharge and space temperatures. There are also controllers for each CRAC unit.

The system integrates dedicated control modules for HVAC and CRAC units via a local area network. It includes a color touchscreen local control interface (LCI) for monitoring and an internet data server that provides e-mail alarm notification, as well as web access to monitor the system from outside the facility.

In order to install the new system with minimal interruption to everyday activity, network installation, mounting of the new control modules and installing the temperature sensors all needed to be accomplished before disabling the existing thermostat system. PBS technicians determined that the existing thermostat wires could be saved to connect the new temperature sensors to the control modules. When the new system was in place, PBS switched the thermostat wires to the new system one unit at a time.

The physical installation of the system only took half the estimated time and the cutover took only one-fourth of the estimated time. Since the modules were self-configuring, two technicians cut over and started 22 units in three-and-a-half hours. Additionally, all areas of the facility experienced minimal interruption.

The facility is expected to see a two-fold increase in employees in the near future. Luckily, the system is able to support up to 64 HVAC controllers. "That's another reason why this system is going to come in handy," Chansilp says. "With all these added inhabitants, we'll be able to control the system from one central point and not have to run around the building like chickens with our heads cut off."





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