Define a trend log in BAS and its usefulness.

Define a trend log in BAS and its usefulness.

• A. A real-time alarm notification list
• B. A backup of all network traffic
• C. A time-stamped record of measurement values used to analyze performance, detect faults, and verify operations
• D. A log of maintenance personnel actions

Answer: (C)

In a BAS, a trend log is a time-stamped record of measurement values from sensors and devices. It collects data points at set intervals for parameters like temperature, humidity, flow, pressure, energy use, valve positions, and setpoints. This historical data lets you analyze how the system behaved over time, spot performance drift or unusual patterns, and verify that control actions happened as planned. For example, you can see how space temperature responds to cooling calls, check whether a damper opened when it should, or confirm that energy use stayed within expected ranges. The trend log is useful for commissioning, ongoing monitoring, energy optimization, and troubleshooting because you can compare current data to baselines, analyze events after faults, and confirm that issues were resolved. It’s not the same as an alarm list, a capture of network traffic, or a log of maintenance actions.

In a BAS, a trend log is a time-stamped record of measurement values from sensors and devices. It collects data points at set intervals for parameters like temperature, humidity, flow, pressure, energy use, valve positions, and setpoints. This historical data lets you analyze how the system behaved over time, spot performance drift or unusual patterns, and verify that control actions happened as planned. For example, you can see how space temperature responds to cooling calls, check whether a damper opened when it should, or confirm that energy use stayed within expected ranges. The trend log is useful for commissioning, ongoing monitoring, energy optimization, and troubleshooting because you can compare current data to baselines, analyze events after faults, and confirm that issues were resolved. It’s not the same as an alarm list, a capture of network traffic, or a log of maintenance actions.