To satisfy the requirements of users in buildings, the visual environment needs to meet certain conditions. Specifically, adequate illuminance levels must be maintained dependent on the rooms' function and usage. Toward this end, electrical lighting must be deployed in many instances. However, the use of electrical lighting and the associated electrical energy use can be reduced by appropriate utilization of daylight. To estimate, in a convenient manner, the electrical energy use for lighting in buildings, there are a number of simplified procedures. An example of such a procedure involves the use of the indicator LENI (Lighting Energy Numeric Indicator). Using this indicator, area-related electrical energy use can be calculated on a room-by-room basis. However, such procedures involve a significant number of simplifications with regard to building geometry, properties of relevant building components (e.g., windows, shading), climatic context and occupancy. In this context, the present master thesis has the purpose to explore the reliability of these procedures and calculation methods presented in the EN 15193 standard. Toward this end, this study compares for a sample of rooms (e.g., lecture room, office space) the results obtained by simplified and detailed calculation methods with results obtained using measurements, in view of electrical energy demand for lighting in buildings. The research results are expected to further define the degree to which simplified calculation results could deviate from more detailed estimations or measurements.