Harnessing flexibility from thermal building mass for emission reduction—A cross-country analysis

As space heating in single-family buildings requires a large amount of energy, its decarbonisation is crucial for mitigating climate change. One approach is to consider the thermal mass of buildings as thermal storage, allowing the space heating demands to be shifted to periods of low carbon intensity. Hence, our primary research question is: What are the emission reduction potentials of emission-minimising load shifting when harnessing thermal flexibility of residential building stocks? We select the single-family building stocks of two countries, namely Ireland and Germany, which differ in terms of climatic conditions, insulation standards and carbon intensities of the upstream electricity grids. Moreover, we investigate the enablers and drivers of the emission reduction potentials, the influence of region-specific weather data compared to a national resolution and the overall associated costs of emission-minimising load shifting. Therefore, we create upscaled building models for single-family houses in the energy system model optimisation framework Backbone for Ireland and Germany. The heating demands, supplied by investable heat pumps connected to investable rooftop photovoltaic modules (PV) and to the upstream grid, are endogenously generated by the building models, and indoor thermal flexibility is realised with an indoor temperature bandwidth from 19 °C to a maximum of 24 °C. Key findings are that the emission reduction potentials of emission-minimising thermal load shifting are substantial for both Ireland and Germany, with 15.3% and 9.4% for our standard scenario and with maximum thermal flexibility, and that strong emission signals are necessary for emission-minimising thermal load shifting.