Which condition could lead to higher energy consumption in a large-building HVAC system that cannot reach setpoints?

Which condition could lead to higher energy consumption in a large-building HVAC system that cannot reach setpoints?

• A. Increasing thermostat setback.
• B. Replacing all equipment preemptively.
• C. Ignoring sensor readings.
• D. Inaccurate sensor calibration and incorrect sequence could lead to control errors.

Answer: (D)

Controlling a large building’s HVAC effectively relies on accurate sensors and correct control sequences. When sensors are miscalibrated, the controller reads the space temperature inaccurately, so the system keeps heating or cooling longer than necessary in an attempt to reach the setpoint. An incorrect control sequence can cause actions to occur in the wrong order or even fight each other, such as cooling and heating running simultaneously or fans cycling unnecessarily, which wastes energy and prevents stable setpoint achievement. Inaccurate sensor calibration and an incorrect sequence directly create these control errors, leading to higher energy use because the system cannot settle at the desired conditions. Other options either reduce energy use (like larger setbacks) or are less direct explanations of persistent setpoint errors.

Controlling a large building’s HVAC effectively relies on accurate sensors and correct control sequences. When sensors are miscalibrated, the controller reads the space temperature inaccurately, so the system keeps heating or cooling longer than necessary in an attempt to reach the setpoint. An incorrect control sequence can cause actions to occur in the wrong order or even fight each other, such as cooling and heating running simultaneously or fans cycling unnecessarily, which wastes energy and prevents stable setpoint achievement. Inaccurate sensor calibration and an incorrect sequence directly create these control errors, leading to higher energy use because the system cannot settle at the desired conditions. Other options either reduce energy use (like larger setbacks) or are less direct explanations of persistent setpoint errors.