Energy saving potential of cooperative operation between district heating and cooling plant and building HVAC systems

District heating and cooling (DHC) systems show a great potential to save energy. However, DHC has a number of problems related to other systems within a building; for example, decrease in the temperature difference between the supply and return water carrying cooling and heating energy affects efficiency. The main reason is that the DHC plant and the building air conditioning systems are operated separately. This study proposes a new energy service in which the operator of the DHC plant controls air conditioning systems at the same time. Using a simulation model, it is found that energy conservation measures at the demand side would decrease energy consumption by 5%.