Setpoint reset automatically adjusts the temperature or pressure target based on outdoor conditions, occupancy, or system performance metrics, reducing energy consumption while maintaining comfort and safety. Rather than maintaining fixed setpoints year-round, reset strategies lower heating setpoints in winter and raise cooling setpoints in summer based on outside air temperature. These strategies can reduce energy use by 10-25 percent in buildings with variable loads.
Technical Details
Common reset strategies include outdoor air temperature reset (adjusting supply water temperature 1-2°F per 10°F outdoor change) and demand reset based on occupancy sensors or CO2 levels. Reset controllers use linear or nonlinear relationships between outdoor temperature and setpoint. Typical ranges span from 85°F minimum to 130°F maximum for heating water setpoints. Reset prevents overheating unoccupied zones and reduces unnecessary cooling during mild weather.
Applications
Supply water reset in hydronic systems maintains comfortable temperatures while reducing boiler runtime. Discharge air temperature reset in VAV systems reduces reheat energy during partial-load conditions. Occupied/unoccupied setpoint reset lowers heating targets at night by 2-4°F and raises cooling targets by similar amounts.
Practical Significance
Setpoint reset reduces annual energy consumption without sacrificing occupant comfort or equipment safety. Properly configured reset strategies prevent short-cycling of boilers and compressors, extending equipment lifespan by 15-20 percent.