GEMOD is an ifeu-developed model for the calculation of the energy consumption for space heating and hot water in buildings. Based on the status quo, the future consumption trajectory may be modelled with a range of different assumptions. Thus, the model can illustrate novel development options for the building sector, impacts of user behaviour, technology development, policy instruments, and identify needs for action. The scope of the balance may range from single construction parts to building stocks of any size. User behaviour can be considered depending on the energetic condition of the building. The model reports the energy consumption separately for individual energy carriers and in the following step computes the primary energy consumption, greenhouse gas emissions and fuel costs.
Based on the duration of the use phase of components and heat technologies, GEMOD calculates the replacement cycles and thus, the optimal timeframe for energy renovations. Furthermore, insulation levels or U-values of components, different renovation levels, and shares of different renewable heat supplies substituting conventional heat technology can be entered as parameters. For this purpose, the project exploring the capacity for insulation of the German building stock included a range of analyses of the development potential of future insulation standards. Moreover, building demolition or new construction and climate change can be defined and varied. In addition to the trajectory of the energy consumption, GEMOD calculates the investment costs and material flows associated with renovation measures.
The German existing building stock is modelled using detailed building categories including 234 building types itemised by building age, type of use (residential buildings, offices, schools, storage) and geometry. Current renovation conditions and boiler stock are reported based on empirical data from the Institut Wohnen und Umwelt GmbH (Institute for housing and environment). The energy demand for heat and hot water is calculated per component in a bottom-up approach, and calibrated to the statistical final energy demand with a top-down calibration.
In addition to the Federal German building stock, the building stocks of Baden-Württemberg and Heidelberg have been entered into GEMOD.
The model is used in a number of strategic projects for the analysis of the federal consequences of restrictions in building insulation, and the efficiency potentials of building insulation and renewable energy. GEMOD further calculates the material flows required for building renovation that acts as the input data for life cycle assessments. GEMOD has been used for the quantification of achieved reductions in the evaluation of multiple energy consulting programmes.