Making Old Terminals Smarter, from LAX to STL
Making Old Terminals Smarter, from LAX to STL
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Making Old Terminals Smarter, from LAX to STL
By: James Rosick Ross Truitt, 3 minute read

It's no secret that U.S. aviation infrastructure needs improvement to meet future demands, and that means upgrading existing facilities and building new ones.

It's no secret that U.S. aviation infrastructure needs improvement to meet future demands, and that means upgrading existing facilities and building new ones.

Whether implementing regular replacements driven by life cycle, or undertaking more extensive renovations, it's important to use modern technology to make old terminals smarter.

Consider two recent projects where modern technology lowered operating costs for systems in aging terminals.

LAX: Unifying Multiple Systems

In late 2008, Los Angeles International Airport (LAX) developed requirements and specifications for a central utility plant (CUP) replacement project, integrating existing HVAC controls in terminals became a requirement for the CUP's new front end. This was no easy task, as existing legacy controls were a hybrid of pneumatic and direct digital control (DDC) from several different manufacturers. The front end was obsolete and no longer supported by the manufacturer, while the fire life safety (FLS) system had been integrated with the HVAC system and would need to be isolated.

The vision for the unification included installing a building automation system (BAS) fiber backbone throughout each terminal building and the new CUP. The team determined that any new system would be open protocol, nonproprietary and based on BACnetTM, a data communication protocol for BAS and control networks. New control panels with BACnetTM controllers and Ethernet switches were installed at strategic locations throughout each terminal to allow for future upgrades and integration, laying the technical foundation for a new state-of-the-art future for LAX.

Installing a new fiber-optic network in the Central Terminal Area (CTA) connected each terminal back to the new CUP, on an isolated network. A new facility monitoring and control system (FMCS) — fully redundant with computer-based controls — now monitors and controls the new, more efficient and eco-friendly equipment in the new CUP. This new system allows operators and maintenance personnel to remotely monitor and diagnose the BAS in each of the terminals and several CTA buildings. Existing "legacy" controls were integrated by converting the proprietary protocols into BACnetTM at each terminal, and uses the new fiber network to provide connectivity to the FMCS in the new CUP. All new HVAC and BAS installations in the terminals at LAX are required to be BACnetTM-compatible and to be integrated into the FMCS.

The new CUP has seven chillers, two boilers, and a combined heat and power (CHP) plant consisting of two turbine generators and two heat recovery steam generators (HRSGs), all controlled by a balance-of-plant PLC system. The FMCS is capable of significant expansion and there are plans to eventually integrate additional systems into to FMCS at LAX. Among them: lighting controls, conveyance equipment and tenant metering.

STL: Improving Efficiency of Air-Handling Systems

Lambert-St. Louis International Airport (STL) spent 2011 in the midst of a major renovation of its Terminal 1 building, including upgrades to the terminal's main air handlers. The terminal, originally designed in 1953, hadn't seen a comprehensive renovation since 1978. The project included full replacement of four of the terminal's main air handlers, including associated controls. The units had control concepts common in the 1970s: constant-volume airflow, three-way hydronic valves, and dual-deck multi-zone configurations. Of particular concern: the multizone control strategy.

The multizone units served multiple independent zones of the building by simultaneously heating and cooling air. The system relied upon dampers to mix the air to meet each zone's specific needs. While the system did work, it worked all the time — simultaneously heating and cooling air for 365 days per year, resulting in high energy costs.

In a perfect situation, the multizone equipment could be replaced with a modern variable air volume (VAV) control strategy by adding air terminal devices in individual zones. But there simply wasn't enough space in the 1950s building to accommodate additional devices.

Having ruled out the typical approach, the project team opted to implement modern controls. First came replacement of thermostats and addition of a full DDC system to affected equipment, followed by reproduction of the functionality of a VAV air terminal device inside the existing ducts within the mechanical rooms themselves.

This second part of the approach proved the most challenging. Fitting components into the space already was difficult, but the location of terminal devices within the mechanical room made system controllability even more difficult. In a typical VAV system the controller senses duct pressure from a location far downstream from the mechanical room, then uses that information to obtain a smooth input signal. If the sensor is near the mechanical room, pressure fluctuations from the fan can result in a noisy signal.

The project team overcame the problem of noisy pressure measurements by putting it to a vote, literally. Fan speed, and therefore system pressure, was set to an initial value and then changed on a regular interval — about every five minutes — based on votes received from each air terminal controller. If an air terminal closed more often than expected, the controller would vote for lower system pressure. Likewise, if an air terminal was open too far, its controller would vote for higher system pressure. Making the system smarter enabled the system to adapt to a situation where a traditional approach would have failed.

Jim Rosick is a project manager and manager of the Aviation Group for Burns & McDonnell in St. Louis. Ross Truitt is a project manager for the firm in Chicago.

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