Transition towards university campus carbon neutrality by connecting to city district heating network

The campus of Tallinn University of Technology consists of 26 buildings with a total annual heat demand of approximately 20 GWh. A local natural gas-fired boiler provides annually approximately 13 GWh of heating to 12 buildings in the campus and 14 buildings are connected to district heating system. This paper analyses the possibilities of replacing the natural gas boiler with district heating. Two systems were modelled using EnergyPRO software and compared to the reference system of the local boiler and heating network: connection to an existing high-temperature district heating network and a low-temperature energy cascade. All the three systems were modelled with two different energy price scenarios. The results were analysed from the perspective of the university campus and the entire city's system. The low-temperature energy cascade connection to the city's network will reduce carbon dioxide emissions by 955 tonnes CO2. The conventional high-temperature connection would reduce the emission by 765 tons CO2. District heating connection will also lead to primary energy savings supporting the university's efforts towards achieving its sustainable development goals. The low -temperature energy cascade utilising the return water of the city's district heating network reduces the heat losses and increases the efficiency of heat and electricity production when compared to the systems with separate campus heating or the conventional high-temperature district heating. (C) 2022 The Authors. Published by Elsevier Ltd.