The transition to low-temperature supply in district heating networks as well as the transition towards renewable heat sources allow the introduction of new technical solutions in the district heating production. In Høje-Taastrup municipality a new heat pump system at the shopping mall CITY2 has been installed. The system supplies the new low-temperature district heating network in Østerby district demo case, including business and nearby hotels, recovering the waste heat from the cooling system.

The new heat pump / district cooling system has a capacity of 1.3 MW heat. The system is partly supplied by the photovoltaic system installed on the roof of the shopping mall (16,300 m² of PV panels). The new DH network in Østerby district is designed to ensure a temperature of 55°C on the supply side and 30°C on the return side, with the furthest user that will be supplied with 53°C, and a flow of 1000 l/h.

The system installed in the shopping mall CITY2

The figure below present the principle diagram of the systems installed in the shopping mall CITY2. The heat pump uses the return flow from the cooling system as heat source to heat up the DH water up to 70 °C, which is then delivered to Østerby district and partly used in CITY2. On the cold side, the heat pump provides part of the cooling load of the shopping center. Furthermore, the extra cooling load is used to supply the district cooling network. Both the cooling system and the new heat pump for the LTDH heating are connected to the solar panels system, ensuring that the DH heating production is based on renewable sources.

Østerby district can be supplied either by the heat pump or by the traditional DH network, which can work as back-up solution. The temperature in the LTDH network is ensured by the mixing loop located at the beginning of the network.

Simplified principle diagram of the cooling system and the new heat pump installed at the shopping mall CITY2

The table below gives an overview of the supply and return temperatures at CITY2 and Østerby district as well as the capacity of the system installed.

More information: uffe.schleiss@htf.dk

  • —
  • Traditional DH
  • CITY2 heating system
  • CITY2 heat pump
  • CITY2 cooling machine
  • Østerby
  • Return temperature (°C)
  • 85
  • 63-80
  • 60-70
  • 6-12
  • 55
  • Return temperature (°C)
  • 45
  • 50
  • 45
  • 10-15
  • 30
  • Capacity (kW)
  • –
  • 2000
  • 1300
  • 1000
  • 400