Low-energy buildings heat supply–Modelling of energy systems and carbon emissions impacts

Construction of new low-energy buildings (LEB) areas is attracting attention as a climate mitigation measure. Heat can be supplied to buildings in these areas through individual solutions, through a small, on-site heat network, or through a heat connection to a close-by district-heating (DH) system. The choice between these options affects the energy supply systems and their carbon emissions far beyond the LEB area. We compare the long-term systems impacts of the three heat-supply options through dynamic modelling of the energy systems. The study draws on data collected from a real LEB area in Sweden and addresses scale-dependent impacts on district heating systems. The results show that, generally, the individual and on-site options increase biomass and electricity use, respectively. This, in turn, increases carbon emissions in a broader systems perspective. The systems impacts of the large heat network option depend on the scale and supply-technologies of the DH system close to the LEB area. •Carbon emission of heat supply options to low energy building areas investigated.•A wide system boundary and indirect effects of residential heating found important.•Low temperature district heating (LTDH) have advantages over individual heating.•Advantages of LTDH depend on future electricity and fuel prices.•An integer programming model for realistic results leads to a flip-flop problem.