Tepelny komfort a energeticka bilance systemu s chladicim stropem (Thermal comfort and energy balance of cooled ceiling systems)

Air-conditioning based on radiant cooling ceilings is a viable option of maintaining optimum thermal conditions without great demands on air distribution in a space. The thesis deals with the theoretical and experimental research of cooling ceiling systems with respect to attainable levels of thermal comfort. A mathematical model solving the internal and external energy balance was created for a room with radiant cooling ceiling based on the theoretical description of heat transfer process within the studied space. The output from the model was used to compare different types of cooling ceilings from the viewpoint of their energy performance. The influence of the room geometry and boundary conditions (internal surface temperatures) on the mean radiant temperature was analysed. A software tool named MRT Analysis was developed to evaluate the mean radiant temperature patterns in a room with cooling ceiling under different boundary conditions. The system with cooling ceiling was compared to a predominantly convective air-conditioning system with respect to achievable levels of occupant's thermal comfort. A measuring system was designed and set up to assess experimentally the thermal environment in a test room with cooling ceiling. The vertical air temperature profiles and occupant's thermal comfort levels in the room were measured and evaluated. The convective heat transfer coefficient (incl. its uncertainty) on the cooling ceiling surface was calculated using the measured temperature profiles. The temperature patterns were measured along a vertical heated panel which simulated a shaded window in summer and its influence on the indoor air temperature; also the width of the vertical convective wall jet and the heat transfer coefficient on a warm window surface were studied experimentally. A typical office room with cooling ceiling was modelled in the ESP-r software. The influence of natural ventilation and window shading on the thermal comfort was studied using the simulations performed in ESP-r for an extreme summer period. Time variations of the operative temperature and predicted mean vote (PMV) were used as the assessment criteria.