Large-scale ceiling heating and cooling in buildings is now widely used in both traditional and new low-energy buildings. The CRITTALL type ceiling heating system is also designed in one of the buildings of the Faculty of Civil Engineering of the Slovak University of Technology in Bratislava. This building is characterised by the fact that its envelope is designed as a lightweight envelope with a high proportion of glazing. Thermal discomfort often occurs during heating operation, especially during warm spring or autumn days. Experimental measurements were carried out in selected reference rooms in order to evaluate the control of the heating system operation, to assess the suitability of the external temperature sensor placement and the selected thermal performance control strategy. The analysis of the results of these measurements showed the following conclusions: the indoor air temperatures exceeded the recommended intervals specified in the Slovak legislative regulations, but their course was uniform. When solar heat gains occurred, the rooms facing south-west showed a significant rise in indoor temperature. The chosen equithermal control strategy is only suitable for the north-east heating zone, but a more appropriate heating curve needs to be set to avoid overheating the space. Ensuring thermal comfort with the control system for the south-west facing zones is problematic due to the different dynamic behaviour of a building with a lightweight envelope and a heating system with a large thermal inertia. In view of this fact, a control system based on forecasting of outdoor temperature and reduces or increases the performance of the heating system in advance would be preferable. As both heating zones are controlled only by a temperature sensor located on the north side of the building, the control circuit of the south-west zone also needs to be supplemented by a separate, functional and suitably positioned outdoor temperature sensor.