What does energy efficiency refer to?

Energy efficiency refers to the practice of using less energy to achieve the same output or perform the same function. This concept emphasizes optimizing energy use to reduce waste while maintaining the same level of service or productivity. When a process, device, or system is energy efficient, it performs its intended function with minimal energy consumption, which contributes to lower energy bills and a reduced environmental impact.

For instance, an energy-efficient appliance, like a refrigerator designed to use less electricity, can keep food cold while requiring significantly less power compared to older models that perform the same task. This not only saves money for consumers but also plays a critical role in reducing overall energy demand and greenhouse gas emissions, promoting a more sustainable energy future.

In contrast, the other options indicate scenarios that do not align with the principles of energy efficiency. For example, using more energy to produce the same output or increased energy consumption run counter to the aim of improving efficiency. Reducing energy costs without changing consumption does not specifically address the quantity of energy used relative to output, which is a key aspect of energy efficiency.