Demand-Limiting Controller

A new version of a patented demand-limiting controller (DLC) from Save Energy America incorporates a number of features to serve small- to mid-sized commercial buildings that have three or more HVAC units. The DLC automatically monitors ambient and external temperatures to intelligently coordinate the HVAC units’ performance to reduce energy costs up to 30 percent. The DLC is a networked system comprised of a central controller and customized thermostats that leverage discrete zone data with current weather and forecasts to automatically manage HVAC energy consumption. The system is accessible 24/7 with browser-based interface that can be viewed on a monitor, tablet, or smartphone. The DLC is also compatible with all brands of HVAC manufacturers and interfaces with motorized economizers. Multiple algorithms in the DLC system address three key components of an electric bill: demand, use, and peak-rate charges. First, demand charges are controlled by not allowing all of the HVAC units to operate simultaneously. Second, use charges are reduced in two ways: by turning the fans on when the outside temperature is 55°F or less, and by managing the second stage of a unit based on the trending data within a zone. Third, the DLC reduces peak-rate charges by cooling zones to a slightly lower temperature prior to peak-rate times and allowing the temperature to drift up to a slightly higher set point during peak-rate periods. The advanced features include fresh air recirculation (based on occupied times, recirculation times or carbon-dioxide levels), integrated management of multi-stage units, AUTO/OFF mode states and enhanced auto demand response. —Save Energy Systems

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