District heating and cooling systems (DHC) are a proven energy solution that has been deployed for many years in a growing number of urban areas worldwide. They comprise a variety of technologies responsible for the production and supply of heating, cooling, domestic hot water and electricity. Although the benefits of DHC systems are significant and have been widely acclaimed, yet the full potential of modern DHC systems remains largely untapped. There are several opportunities for improving the efficiency of DHC systems, which will enable the exploitation of renewable resources, waste heat recovery, etc., in order to facilitate the transition towards next generation of DHC systems. This motivated the need for modelling these complex systems. Large-scale modelling of DHC-networks is challenging, as it has several components interacting with each other. In this paper we present two methodologies to model the consumer buildings. These models will be further integrated with network model and the control system layer to create a virtual test bed for DHC system. The model is validated using data collected from the DHC system located at Lulea, Sweden. The test bed will be then used for simulating various test cases such as peak energy reduction, overall demand reduction etc. prior to real world testing.