Energy efficiency is a sum of planned and realized measures and its goal is to use as little as possible of energy thus the level of cosines and the productivity rate stay preserved. Simply to put - the energy efficiency is using the smaller amount of energy (energents) to perform the same activity or the function (heating or cooling of the closed spaces, lighting, production of different products, car drive, etc.)
It is important to say that it is not right to see energetic efficiency as energy savings because the savings implies certain depravings, while the efficient usage of energy never disrupts the working and living conditions. But, more important is that the improved energy efficiency results in decreased consumption for the same amount of products or services which brings at the end money savings in the same proportion.
