The U.S. Office of Energy Efficiency and Renewable Energy explains “energy efficiency” best:
Energy efficiency is the use of less energy to perform the same task or produce the same result.
Energy-efficient homes and buildings use less energy to heat, cool, and run appliances and electronics,
and energy-efficient manufacturing facilities use less energy to produce goods.
Energy efficiency is one of the easiest and most cost-effective ways to combat climate change, reduce energy costs for consumers,
and improve the competitiveness of U.S. businesses. Energy efficiency is also a vital component in achieving net-zero emissions of carbon dioxide through decarbonization.