This master's thesis deals with the subject of visualization of data collected through sensors in the Internet of Things system through research of user perception and design of visualizations for Building Management Systems. The central points of the thesis are a questionnaire on visual perception, designed visualizations and A/B testing. The IoT system consists of four components – sensors, connectivity, data processing and user interface. Data collected in the IoT system as such are not of great value, but when meaningfully processed and shown correctly, they can be very meaningful. The aim of the research was to show the possibilities of data visualization in BMS through design, the description of the process and the perception of visualizations. The results will show in more detail the possibilities of data visualization and solving the problem of combining a smart system with the regulation and control of energy consumption. Instruments used for data collection in the experimental part of the thesis were two online questionnaires with assessment and ranking scales. Methodological procedures used were surveying, assessment and ranking. The first part of the research was conducted on a sample of 159 participants, while the second part of the research was conducted on a sample of 30 participants. Final representations of data visualization possibilities and design conclusions were designed according to research results.