HVAC Scheduling and Setback Strategies for Commercial Buildings
One of the simplest and most cost-effective ways to reduce commercial AC energy consumption is also one of the most commonly overlooked: not running it when you don’t need to. Implementing intelligent scheduling and temperature setback strategies can cut HVAC energy use by 15–30% with minimal capital investment.
The Cost of Always-On Operation
Many commercial HVAC systems run at or near full capacity continuously — through the night, over weekends, and during holidays. For a building occupied 60 hours per week, that leaves 108 hours per week of unnecessary cooling. At commercial electricity rates of $0.10–$0.15 per kWh, the cost of conditioning an empty building adds up to thousands of dollars per month.
Temperature Setback Explained
During unoccupied periods, the goal isn’t to turn the AC completely off — extreme temperature swings are hard on equipment and take significant energy to recover from. Instead, setback raises the cooling setpoint (and lowers the heating setpoint) to a range that protects equipment and inventory without conditioning the space to occupied comfort levels.
Typical setback targets:
Occupied cooling setpoint: 72–75°F
Unoccupied cooling setback: 85°F
Pre-occupancy ramp-down: Begin 30–60 minutes before occupancy, based on outdoor conditions
Optimal Start/Stop Algorithms
Modern BAS platforms include optimal start algorithms that calculate the exact time to begin conditioning a space based on current indoor temperature, outdoor temperature, and historical data about how quickly the building responds. This eliminates both the waste of starting too early and the comfort complaints of starting too late.
Special Considerations
Server rooms and data centers: These spaces require continuous cooling regardless of building occupancy.
Restaurants and kitchens: Pre-cooling before kitchen equipment starts operating saves energy by building in a thermal buffer.
Retail spaces: Coordinating HVAC schedules with store hours and factoring in early morning stocking activities avoids unnecessary cooling.
Humidity-sensitive spaces: Some facilities (museums, laboratories, medical offices) require continuous humidity control even when unoccupied.
Implementation Without a Full BAS
Even without a sophisticated BAS, programmable thermostats in individual zones can implement basic scheduling. While less precise than a centralized system, properly programmed zone thermostats deliver meaningful savings at very low cost.