Energy demands, especially electrical, will grow steadily. The need for rational use of energy first emerged globally during the 1973 oil crisis. As a consequence of this crisis, many states have tightened energy regulations to reduce energy consumption, and among them have been regulations related to increasing energy efficiency (EE) in buildings. The interest in energy efficiency has come back into focus when research has shown the great impact of energy consumption on climate change. Generally, when it comes to energy, we distinguish between two categories of energy savings: energy conservation and energy efficiency. These two terms differ significantly. The paper will interpret these two terms in a series of examples. When it comes to the term energy efficiency, the most commonly thought of is energy efficiency in buildings. In the paper we will pay special attention to the areas that are less discussed when it comes to energy efficiency, such as chimney sweeps, Serbian traditional architecture, power plants in healthcare institutions, predictive maintenance (just in time maintenance) of devices and equipment, especially those in healthcare institutions... Energy efficiency also plays a key role in combating energy poverty. Also, the paper will highlight the need to raise the level of knowledge of the Serbian population about the importance of EE through systems of formal and non-formal education. The concept of energy efficiency has two meanings: one refers to technical devices (e.g. electrical machines)-devices are energy efficient if they have a high degree of efficiency (small losses in converting one form of energy into another), and the other-to certain specific measures and behaviors that are applied to reduce energy consumption. However, it should be especially emphasized that energy efficiency should not be viewed as energy conservation, but, as the term itself says, as an efficient use of energy that should not undermine defined standards of working and living environment.