This study examines the domestic hot water consumption of a Danish dorm building with 50 residens, located in Aalborg. The aim of the study is to investigate consumption patterns regarding domestic hot water, and to investigate the impact that the circulation system has on the energy consumptions and energy losses in the domestic hot water system. The average, typical domestic hot water consumption was \SI{47,1}{L/person/day}, equivalent to \SI{419,4}{L/m^2/year}. In general, the domestic hot water consumption was found to be evenly distributed throughout most of the day, while typical week days also have a morning peak between 07:00 - 09:00.

The circulation system was to found to have a major impact on the efficiency of the domestic hot water system, by consuming between 28,19 - \SI{49,28}{\%} of the district heating delivered to the domestic hot water system. Furthermore, the circulation system leads to a low utilization of the delivered district heating, corresponding to an average temperature difference of 15,38 - \SI{16,08}{\degree C}, between the delivered and consumed district heating.
The efficiency of the domestic hot water system was estimated to 33,56 - \SI{36,67}{\%}, including energy for circulation losses, while the efficiency of the domestic hot water production alone was estimated to 44,56 - \SI{66,22}{\%}, excluding circulation losses. This shows that circulation systems can have a big impact on the overall efficiency of domestic hot water systems in dwellings such as the examined property.