Historically, hot water boilers in buildings have been controlled with a setpoint for the hot water they generate. In the days before energy efficiency was paramount and the environmental impact of energy systems in buildings was top of mind, boilers were often set and controlled to a static (never changing) setpoint. While this was a simple approach to program building automation systems, it is not the most efficient way to program boiler controls.
In one particular project, CopperTree analyzed the performance of the heating system of a building and realized that the hot water supply temperature was using a static 130 deg F setpoint, regardless of what the temperature outside was.
Most boilers and their built-in controllers feature the ability to enable several ”modes of operation”, although typically these require specific programming and in some cases additional sensors or wiring to enable them. In this case, those more efficient modes were either never implemented, or overridden throughout the course of the building’s many years of operation.
CopperTree’s Kaizen FDD system includes algorithms to analyze all equipment setpoints and process variables in order to gauge which processes are potentially less efficient than they could be. In the case of this project, it was determined that the boilers were not using the most efficient “modes of operation” available to them. By operating the boilers at a static supply temperature setpoint of 130 deg F, the building was always behaving as if it were only 20 deg F outside (-6.7 deg C). CopperTree recommended implementing a boiler outdoor air reset strategy, so that the boiler supply temperatures will vary with the outdoor air temperature, since that would be closely tied to heating demand for the building.
By allowing the supply water temperature setpoint to dynamically ramp up and down with the outside air temperature, this customer’s building was able to save tens of thousands of dollars per year in gas energy costs and reduce its carbon footprint significantly.
