Which of the following best defines "energy efficiency"?

The definition that best encapsulates "energy efficiency" is the reduction of energy consumption while maintaining the same level of service. This concept emphasizes achieving optimal performance and similar outcomes with less energy usage. For instance, energy-efficient technologies or practices allow households and businesses to lower their energy bills and environmental impact without sacrificing comfort or productivity.

This understanding is critical in sustainability efforts, as enhancing energy efficiency directly contributes to reducing overall energy usage and carbon emissions, making it a pivotal strategy in addressing climate change and conserving resources.

The other options do not accurately capture the essence of energy efficiency. Using more energy to achieve the same result is counterproductive to the idea of efficiency. Producing energy from renewable sources is valuable but does not illustrate the concept of using less energy for the same output. Implementing energy-efficient appliances is related but does not encompass the broader definition of energy efficiency as a practice across various scenarios beyond just appliances.