Grid operators are the companies responsible for the operation, maintenance, and expansion of electricity and gas networks. They provide the connection for customers to the energy grid and ensure the infrastructure necessary for the transmission and distribution of energy within a specific area. Grid operators are thus responsible for a continuous and stable energy supply to buildings, as well as the monitoring and control of the energy network. With the rising demand for energy, expanding grid capacity also falls under the grid operators' responsibilities. Each region has a single responsible company, and grid operators cannot be freely chosen. For their services, grid operators receive network fees, which are listed on consumer bills and included in electricity or gas prices. These fees are passed from energy suppliers to the operators. Grid operators contribute to the stability of the overall electricity network through intelligent control and load management, making them key players in smart building operations. By supporting the integration of renewable energies, they enhance the efficiency and sustainability of buildings and building complexes. They also play a crucial role in the implementation of grid-interactive building complexes and in the overall energy transition.