Heating systems must be subjected to hydraulic balancing in order to ensure proper operation. When the heating system is hydraulically imbalanced, heat is unevenly distributed across dwellings resulting in a large temperature spread, overheating, and consequently, waste of energy. In this study, we investigate the extent to which hydraulic imbalance affects the thermal energy consumption in buildings. Furthermore, key variables and interactions that influence the thermal performance in buildings are identified. Results show that higher variation in indoor temperature lead to higher energy consumption. Compared to new buildings, old buildings that have large boiler capacity and small heated floor area are more likely to be hydraulically imbalanced and to consume more energy.