Digital garage ventilation system delivering 97% energy savings at S.F. garage
Photo courtesy of NES
Nagle Energy Solutions’ (NES) patent-pending garage-ventilation control system is cutting by more than 1.2 million kilowatt-hours (kWh) a year the baseline of consumable energy by a new and sizeable mechanical ventilation system at the city of San Francisco’s Japan Center Garage.
By doing so, the NES system provides a recurring operational-cost savings in excess of $250,000 per year — not including future utility rate increases, according to a press release.
Real-time data logging shows that, in the 10 months since NES system commissioning (early March 2017), the energy consumed by 45 new electric motors running 20 hours per day and possessing a combined 225 horsepower amounts to just 31,900 kWh. That correlates to just 38,300 kWh consumed annually — a 97 percent reduction from the 1.25 million kWh per year the same mechanical system would otherwise consume with no means of fan-motor control in place.
“Post installation operating hours for the new mechanical ventilation system increased by more than 500 percent from the prior 12-month period with the original system, so we fully anticipated our monthly/annual energy bill would increase. But with the NES system controlling it, the garage’s kilowatt (kW) demand has decreased considerably,” said Rich Hashimoto, corporate manager of the Japan Center Garage Corp. and president of the Japantown Merchants Association. “Our estimates show the NES system will actually reduce our building operation costs by more than $5,000 from the prior year. For any system to achieve that kind of results is remarkable.”
Recent updates to the California Energy Code (Title 24) required the San Francisco Municipal Transportation Agency (SFMTA) to upgrade the mechanical ventilation systems of some of the City’s aging garages, including the Japan Center, Golden Gateway and Sutter Stockton garages, each of which now deploys the NES digital, demand-control ventilation (DCV) system.
The Japan Center Garage, which includes a Main and an Annex facility encompassing a combined 300,000 square feet, was constructed in 1968. Retrofit plans included the replacement (by third-party vendors) of the original 45 5-horsepower (HP) fan-motor units dispersed throughout the respective garages with new, equivalent-size motor units. Plans also included the use of variable frequency drive (VFD) technology in conjunction with the operation of each, new motor.
The NES garage DCV system controls the rate of ventilation in the Main and Annex garages based on carbon monoxide (CO) concentrations at a given juncture. BACnet-communicating NES carbon monoxide (CO) sensors provide instantaneous feedback to NES controllers, which then relay speed commands — via VFDs — to the garage’s exhaust and supply fan motors, increasing and decreasing motor speeds in proportion to CO readings.