In this study, three identically designed model buildings and their heating energy consumption was compared. Those pilot scale buildings are equal by size and were located on the same location. During the measuring campaign both external and internal temperatures were recorded, beside the energy consumption. The model buildings were labeled as A (constant baseline), B (baseline varying according to a time program), and C (unheated, blank). During the measurements, the thermal mass of the buildings was altered. The same amount of thermal mass was installed in all three model buildings during all measurements. According to our results under real weather conditions, the intermittent heating requires less energy than maintaining a constant temperature, and the energy saving is inversely proportional to the time constant at intermittent heating. Instead of specific heat mass, a thermal time constant was used to compare intermittent and constant heating. It was established that as the thermal constant of the model building increases, the energy savings between maintaining a variable base temperature and maintaining a constant base temperature decrease. The expected savings are between 4% and 7%.