What function does a motion sensor serve in energy management?

A motion sensor plays a crucial role in energy management by minimizing energy usage through occupancy detection. It achieves this by detecting the presence or absence of individuals in a space. When the sensor detects motion, it can signal connected systems, such as lighting or heating, to turn on, ensuring that energy is only used when necessary. Conversely, if no motion is detected for a specified period, these systems can be programmed to turn off or adjust their settings, thereby conserving energy and reducing costs.

The other options do not align with the primary function of motion sensors in energy management. For instance, triggering emergency alerts pertains to safety systems rather than energy conservation. Collecting user preferences typically involves more complex configurations, like smart home systems with user input for settings, which is not the basic function of a motion sensor. Determining the time of day does not relate to the primary goal of minimizing energy usage; instead, it involves time-based scheduling rather than responsive action based on occupancy.