IIT Research Validates Energy Savings & Indoor Air Quality Advantages of NES Ventilation Control System

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Provides Framework for Optimizing Energy Consumption in Enclosed Parking Garages

The NES garage control system routinely captures kWh and peak kW demand savings in the range of 95% – and up to 97% in many instances.

The IIT team’s research demonstrates that the NES approach provides significant fan-energy savings while meeting indoor air quality requirements.

A peer-reviewed technical paper by researchers in the Department of Civil, Architectural and Environmental Engineering at the Illinois Institute of Technology (IIT) quantifies the distinct energy saving and air quality advantages delivered by the Nagle Energy Solutions (NES) demand-control ventilation (DCV) system when compared to the predominant ventilation control strategies currently employed in enclosed, commercial parking structures.

The technical article was published recently in Building Simulation, An International Journal, which peer-reviewed the NES application, featuring it as a model for optimizing building construction methods and practices. IIT researchers combined multi-zone airflow and contaminant transport modeling (CONTAM), fan affinity laws and realistic assumptions for vehicle traffic patterns and carbon monoxide (CO) emissions – confirmed with actual traffic and gas measurement data – to predict the impacts of various ventilation control strategies on indoor air quality and fan energy use in parking garages.

The IIT analysis determined the NES control strategy – which makes use of variable fan-motor speed responses to measured CO concentrations – considerably outperforms the other control strategies in minimizing annual energy consumption while maintaining CO concentrations below required thresholds.

"To the best of our knowledge, this was the first-ever demonstration of using CONTAM’s dynamic control functions to model airflow patterns, contaminant concentrations and energy consumption in an enclosed parking garage ventilation application, and it led to novel findings on the effectiveness of the NES system,” stated Brent Stephens, professor and chair in the Department of Civil, Architectural and Environmental Engineering at IIT.

The IIT report compares four ventilation control methodologies, which were modeled using actual parking garage occupancy and traffic pattern data and different fan configurations, as well as real-time energy (kW) consumption and CO concentration data recorded continuously at actual sites where NES technology is deployed.

As part of the study, the IIT team investigated fan energy use, peak power demand and resulting CO concentrations for the respective control strategies under a variety of assumptions. As an example, each control strategy modeled scenarios reflecting “warm” starts, i.e., a vehicle’s catalytic converter is minimizing CO output, and “cold” starts, i.e., maximum CO concentrations are being emitted.

The four ventilation control strategies include:

  • Standard Variable Flow (SVF), in which the fan is operated at 50% of maximum speed and then is increased to 100% of maximum speed until CO concentrations reach below 25 parts per million (ppm).
  • On-off during operating hours, in which the fan operates at 100% of maximum speed when CO concentrations in any zone reach 25 ppm and 0% of maximum speed when CO concentrations are maintained below 25 ppm.
  • Always on during operating hours, in which the fan operates at 100% of maximum speed regardless of CO concentrations.
  • NES control strategy, which enables variable fan speeds in response to changing CO concentrations.

According to the results of the published paper, the NES control approach was demonstrated to be 84% more energy efficient than Standard Variable Flow systems, 73% more when compared to On-off systems and 98% with regard to fan motors being always on. The margin of error in percentage of savings for NES versus SVF is ± 0.5%. The margin of error in percentage of savings for NES versus On-off is ± 3.6%. The margin of error in percentage of savings for NES versus Always on is ± 0.1%.

“The IIT team’s research demonstrates that the NES approach provides significant fan-energy savings while meeting indoor air quality requirements, and the means and methods for motor control utilized by NES provide a basis for further optimization and evaluation of ventilation control strategies in enclosed garages," noted Professor Stephens.

“The IIT team’s findings firmly establish NES as the pacesetter in the garage ventilation controls industry,” stated NES Founder Frank Nagle. “The fact that the IIT team utilized empirical data provided by us buttresses NES’s innovative approach – including our measurement and verification methodologies – which sets the standard for what’s attainable performance and energy savings-wise.”

A downloadable version of the technical paper is available on Building Simulation at:
https://link.springer.com/article/10.1007/s12273-020-0677-3. Supplementary materials on air flow rates and fan power draw and peak demand can be found at: https://rb.gy/nw9exh. Terms of use include sharing, adaptation, distribution and reproduction in any medium or format, as long appropriate credit is given to the original author(s) and the source, a link is provided to the Creative Commons license (at: https://creativecommons.org/licenses/by/4.0/) and changes made are indicated.

About Nagle Energy Solutions: Based in San Mateo, CA, Nagle Energy Solutions, LLC (http://www.nagle-energy.com) develops, manufactures and distributes an innovative DCV system for commercial garages which markedly reduces energy consumption by increasing operational efficiencies.

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