Component Supply Center HVAC System Replacement
King County
Seattle, WA

Wood Harbinger served as the prime consultant to the County providing mechanical and electrical engineering design to replace the HVAC system, including an upgraded Direct Digital Controls (DDC) system, for Metro Transit’s Component Supply Center.  The Component Supply Center provides maintenance for transit buses, trolleys, and County vehicles, and includes a 11,600 SF Body Shop and 2,000 SF Hazardous Materials Bay.

Wood Harbinger replaced three heat recovery units, associated controls, and the gas-fired infrared heating system.  The upgraded DDC system interfaced with air handler and heater packaged unit controls.  As this equipment supplied conditioned air for diesel vehicle repair bays, critical factors for this design included using 100% outside air for air quality control, energy efficiency, and heat recovery.

Carbon dioxide, volatile organic compounds, and particulate sensors are required in a maintenance facility to ensure occupant safety.  Prior to the equipment selection, a life cycle cost analysis was prepared and presented to the County that compared two options for maintaining air quality and reducing energy usage: a Distributed System, which includes many CO2 sensors located throughout the facility at specific sample locations; or a Central System based on Aircuity, which includes a central location for the sensors.  After evaluating the benefits of each system, and the life cycle cost analysis, the owner chose to install the Distributed System option.

Wood Harbinger also provided commissioning services for this project. Our reviews helped refine the design and control sequences, and functional testing validated and fine-tuned the equipment operation after installation. Commissioning revealed some misinterpretation of the sequences during implementation, which was corrected during functional testing. This correction reduced energy consumption and improved air handler operation stability.