The publication focuses on assessing the energy efficiency in residential and to some extent commercial applications. An energy audit is always the first step in addressing energy efficiency. The purpose of the publication is to present the benefits of using an energy audit. It explains a “do-it-yourself” procedure for an energy audit. The publication also focuses on calculating the potential energy saving by updating low-efficiency electric appliances with high-efficient alternatives. The environmental benefits of addressing the energy efficiency of households is also being discussed. An energy audit using a “do-it-yourself” procedure focuses on the economic, ecological and social impact to environment. The energy audit contributes to the implementation of the concept of sustainable development in our day by day life.