Re-Optimizing Optimal Start & Morning Warm-Up

Standard industry practice is to set back zone temperature setpoints when commercial buildings are unoccupied. HVAC systems then operate in warm-up mode to recover zone temperatures prior to the start of occupancy. These strategies, originally developed to reduce HVAC energy consumption, are due for re-examination with the movement toward electrification. Warming up a building as fast as possible may not be the best strategy in terms of energy use, operating cost or carbon emissions. This article discusses some downfalls of conventional morning warm-up practices, suggests an improved strategy and shows results from a pilot field demonstration test.