There is a large number of existing buildings and new constructions in Slovenia, for which the owners don't know what energy properties their buildings are showing. In comparison to new constructions, the bigger problem are proving to be with existing buildings, where the problems are in obtaining information and details of the analysis for the calculation of these properties. The goal of the thesis was to design a web application which would be used by the general public that offers information about the energy performance of building, using the building typology.
When designing the application, a key assumption was that the user supplies only information which is not already contained in existing public databases in order to facilitate the process of obtaining results. Precise details of buildings were obtained from the databases of the Geodetic Administration of the Republic of Slovenia. The obtained data were properly structured and a data model of buildings was designed, which the application offers to the user. A further procedure requires from the user only a basic description of the thermal building envelope. For example it is necessary to define the materials in structural elements of roof, wall and floor. Based on the data entered by the user and acquired from the model of buildings, the application seeks for a specific typical building, which is showing similar characteristics to the user one. We have made a thorough review of typical buildings from project Intelligent Energy Europe Tabula, which represents the latest building typology in Slovenia. The results of the project Tabula were used to design a specific procedure to search for a most appropriate typical building based on data specified by the user. This procedure takes into account the construction period of the building as well as building size. With all collected data, the building is first categorized in one of the six periods of construction and then on the basis of surfaces of structure elements and its heat transfer coefficient, seeks for the most similar typical building and assigns its energy indicators as a final result. We adapted the OntoWiki system to the algorithm requirements and made a prototype application. The last part of the thesis is a comparison of the actual data on delivered energy, derived from the E-TOOL, with results given by the application, with which we evaluated the nature of such allocation of energy indicators and gave reasons for the deviations.