Which of the following is a feature of energy-efficient elevators?

Automatic energy-saving modes are a key feature of energy-efficient elevators. These modes enable the elevator system to optimize its energy consumption by using sensors and control algorithms to reduce power usage when the elevator is not in active use. For instance, when there are no calls for service, the elevator can enter a standby mode where it reduces its standby power or even goes into sleep mode until it's needed again. This results in significant energy savings, especially in buildings with low traffic during certain times.

While the use of heavier materials, decreased operational speed, and increased weight capacity may influence the performance or structural integrity of an elevator, they do not inherently contribute to energy efficiency. Energy-efficient elevators focus primarily on minimizing energy consumption and enhancing sustainability through intelligent operational protocols rather than through these aspects.