Evaluation of positive energy districts with district heating and heat pumps
Abstract
The transformation of districts into Positive Energy Districts (PEDs) is one of the major EU goals on the path to a sustainable building stock. When connecting PEDs to district heating (DH) systems, which typically rely on non-renewable sources, the energy balance requires careful consideration. Methods for calculating the necessary photovoltaic energy to achieve a positive balance are not yet available. To consider different energy carriers, the energy demands have to be converted to primary energy or CO2 emissions. In addition to the annual energy balance typically used in PED calculations, time-depending methods, i.e. monthly conversion factors, address the impact of seasonal variations on energy demand and supply. These methodologies are applied to a case study of a realized residential district in Austria, where comprehensive monitoring data is available. Alternative system concepts (DH, heat pumps (HP) and different combinations of DH and HP) are investigated by applying different balancing methods. Insights into the challenges and feasibility of achieving PED for multi-family buildings in urban areas with DH are derived.