ROI’s experience with low temperature air distribution is not limited to buildings.  We have been involved with PCA (Pre-Conditioned Air) systems for aircraft cooling at LAX, SFO, SEA-TAC, Sky Harbor, Miami, DFW and Bangkok airports.

 Aircraft cooling has many unique design requirements that are totally foreign to most design firms.

The fan and coil systems must be selected to provide 23°F to 25°F supply air temperatures with a discharge static pressure that can exceed 30" water column.  To make these systems work correctly, the defrost cycles must be implemented and integrated into overall system operations.

We worked with one manufacturer and redesigned their defrost system, reducing their defrost time by 75%, allowing greater volumes of cold air to reach the plane with fewer interruptions caused by the defrost cycle.

Proper integration of Thermal Energy Storage into these system is critical, as is the ability to respond to rapid changes in the cooling loads.  It is possible for a cooling load to jump from 5%, if there are only a few planes at the gates, to over 100%, if several planes hit the gates within a few minutes of one another.

Just as critical, and more difficult to deal with, is the decreasing load as the planes all leave the gates within a few minutes of each other, as the cooling load can drop from 100% to almost nothing.  

Working with these systems has taught us much about system responsiveness and fault tolerance.   Our sequences of operation have been honed on these systems that demand almost instantaneous large scale changes in their operations as the load increases and decreases rapidly.   This experience has carried over into the more typical HVAC realm of work, and helped our projects meet the instantaneous needs of the load, while minimizing the energy impact of the required system changes.

The HVAC system using our sequences of operation will tend towards minimum energy use until a change in load is sensed, then the system will respond rapidly to meet the needs of the load.  Once the load has been satisfied, the system will once again reset itself towards minimum energy use.

When developing our software routines, we always remember that the intent of the HVAC system is to meet the needs of the clients - once those needs are satisfied, it is up to us to minimize the energy use associated with that process.

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Aircraft Cooling (PCA) | LA County Sheriff's Headquarters Building