What does energy efficiency mean?

• A. Using more energy to accomplish the same task
• B. Using less energy to accomplish the same task
• C. Losing energy in a system
• D. Using energy from renewable sources only

Answer: (B)

Energy efficiency means using less energy to accomplish the same task. When a device or system does the same job but with fewer energy inputs, it’s doing its job more efficiently. For example, modern LED lights give the same amount of brightness as older bulbs but use much less electricity, and insulation in a house helps keep heat in or out so you don’t have to use as much heating or cooling. The other ideas aren’t about efficiency: using more energy for the same task is the opposite of efficiency, energy loss means energy is wasted as heat or other forms instead of doing the desired work, and using energy from renewable sources only is about where the energy comes from, not how much is used.