What does a well-functioning heating system look like? Investigation of ten Danish buildings that utilize district heating efficiently

In order to reach targeted 4^th generation district heating temperatures around 55 °C supply and 25 °C return, it is necessary to ensure that heating installations inside buildings are designed and operated properly. In this study we investigated the best-case of current design and operation of building installations with the aim of identifying whether there is a gap between current best-case examples and future temperature targets. The study included 7 single-family dwellings and 3 apartment buildings, that were selected based on their low district heating return temperature. Data from the building substations showed that single-family dwellings obtained return temperatures in the range from 25-30 °C while the apartment buildings had return temperatures in the range of 30-40 °C. This indicates that there is a gap between the best functioning heating installations in apartment buildings today, and the targeted district heating return temperatures of 25-30 °C in future 4^th generation district heating networks. District heating return temperatures in the range of 30-40 °C could however be the initial ambition for the existing buildings all around Europe that are expected to be connected to new district heating systems in the near future.