Nagle Energy Solutions’ (NES) patent-pending garage-ventilation control system has reduced energy use by more than 1.2 million kilowatt-hours (kWh) at the city of San Francisco’s Japan Centre Garage.

In dollar terms it is a recurring operational-cost saving in excess of $316,000 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 per cent 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.

The corporate manager of the Japan Centre Garage, Rich Hashimoto, said the system is generating significant savings.

"Post installation operating hours for the new mechanical ventilation system increased by more than 500 per cent 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," Hashimoto said.

"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 results like this 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 ageing garages, including the Japan Centre, Golden Gateway and Sutter Stockton garages, each of which now deploys the NES digital, demand-control ventilation (DCV) system.

The Japan Centre Garage, which covers 300,000 square feet, was constructed in 1968. Retrofit plans included the replacement (by third-party vendors) of the original 45 five 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 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.

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