HVAC Retrofit Returns 53 Percent in Fan Energy Savings

HVAC Retrofit Returns 53 Percent in Fan Energy Savings

This piece was originally published in the August 2018 issue of electroindustry.

Paul Wickberg, Executive Vice President of Sales, SMC

When a prominent developer, investor, and manager of commercial properties in Northern California and Northern Nevada retrofitted seven rooftop HVAC units with Software Motor Company (SMC) motors, it saw total annualized HVAC fan energy savings of 53 percent.

The company, with more than four million square feet under management, is committed to sustainable and resilient asset management, including energy performance improvement across its portfolio.

Approach

The company had a specific goal to optimize HVAC system energy efficiency and make it intelligent. The ideal HVAC solution would:

  • remotely correlate rooftop unit (RTU) motor data with thermostat data collected by its building automation system;
  • evolve from scheduled to predictive maintenance operations and dynamic maintenance scheduling; and
  • feature remote monitoring and fault detection for better service quality so its facilities team could respond to HVAC issues before customers had complaints about how the system was performing.

Project Scope

Pilot to retrofit a property’s seven RTUs by replacing existing 1 hp fixed-speed induction motors with 1 hp smart motors

Building Location

20,000-square-foot building in Santa Rosa, California

Solution: Smart Motor System

The smart motors feature a patented switched reluctance design. Industry results highlight exponential improvements against standard induction motors in performance capabilities including:

  • Torque
  • Power density
  • Efficiency
  • Versatility

The smart motor system combines Internet of Things (IoT) building automation technology to help building operators, facility managers, and certified contractors create intelligent and efficient energy systems. It provides real-time visibility and actionable insights for key components of commercial and industrial buildings. The motors use electricity only when needed to perform useful work and are less expensive to own and operate than conventional induction motors.

Results

By replacing seven induction motors in RTU applications with smart motor systems, the company realized:

  • total annualized fan energy savings of 53 percent;
  • power draw savings of 30 percent in heat/cool mode (1,550 RPM) and 87 percent in vent mode (690 RPM); and
  • monthly energy savings of 881 kWh with energy use reduced from 1,659 kWh before the project to 778 kWh after it.

The system’s remote monitoring capabilities also let SMC detect when a motor pulley broke and alerted maintenance teams that it needed to be fixed.

Conclusion

By replacing seven motors in its RTU HVAC system, the company achieved total annualized fan energy savings of 53 percent. The significant energy savings and reduced peak demand shrank the building’s carbon footprint and improved the company’s operations tied to sustainability and resiliency.

The simple motor design and predictive maintenance capabilities made the system more reliable and resilient. Equally important for a company that owns and leases office space, the company could better monitor and control comfort levels for the building’s occupants.


One thought on “HVAC Retrofit Returns 53 Percent in Fan Energy Savings

  1. The unfortunate part of this article is that it does not show the overall system – it simply implies motor replacement. While there are some efficiency gains by moving to ECM or permanent magnet motors over induction motors, by no means is an ECM motor as compared to an induction motor of the same power rating, 53% more efficient. The bottom line here is that power is power and you cannot cheat Mother Physics.

    My thought is that the SMC motors were installed but had a controller on them reducing their speed and taking advantage of the pump and fan affinity laws whereas the induction motor system was controlled by across the line starters. This would account for such a large change in efficiency.

    I would like to see the same comparison done by simply putting VFDs on the induction motors and implementing the same Building Management System control. I’d bet the farm that the difference in efficiency gains between the two types of motors would not be anywhere close to 53%.

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