Guideline VDI 2166 Part 1 applies to medium-voltage and low-voltage equipment. The aim is to describe the installation-specific requirements for the controlling of electrical energy under consideration of the purpose in each case. The guideline wants to depict in a system-independent way the functionalities and interrelations within the electro-technical building equipment for recording the electrical energy consumption of different energy services, and show concepts for differentiated measurements for a reasonably accurate establishment of consumption values.