Field Study of HVAC Cost Optimized Supply Air Temperature Reset (CORE)

Multi-zone variable air volume heating, ventilation, and air-conditioning systems are widely used in commercial buildings, but their performance varies significantly. Recent studies have found 4 to 15 percent variation in heating, ventilation, and air-conditioning energy consumption between different supply air temperature reset strategies in multi-zone variable air volume heating, ventilation, and air-conditioning systems. Cost Optimized Reset is a dynamic, cost-responsive, supply-air-temperature-reset solution that minimizes heating, ventilation, and air conditioning cost by optimizing heating, cooling, and fan energy use. The objectives of this research demonstration project were to 1) refine the Cost Optimized Reset algorithm for wider adoption in commercial buildings in California, and 2) demonstrate the operation of Cost Optimized Reset in at least two buildings, evaluating energy and cost impacts. The project team improved upon an existing version of Cost Optimized Reset by adding smoothing factors to improve its operational stability, updating the calculations in the algorithm to account for different types of heating, ventilation, and air-conditioning systems, and creating versions of Cost Optimized Reset that can operate with partial or no zone-level data in multi-zone variable air volume systems so that it may be adopted in buildings that do not have such information available.