Bachelor's thesis Jonas Baumgärtner


Determination of optimized building energy systems for the German residential building stock with special consideration of ventilation losses

Pareto fronts of the annual costs Copyright: EBC Pareto fronts of the annual costs and CO2 emissions for single-family and two-family houses in the construction age classes 1860 - 1957, 1958 - 1978 and 1979 - 1994 as well as the cost levels of the buildings in the stock

In order to minimise the greenhouse gas emissions of German residential buildings within the framework of Germany's climate protection targets for the year 2050, the current renovation rate for old buildings must be almost doubled. Within the framework of this work, a plan for the efficient renovation of the existing residential buildings is therefore being developed.
For this purpose, a "Mixed-Integer Linear Programming" optimization model for building energy systems will be used to determine the economically and ecologically energetic changes to the existing buildings stock.

The German residential building stock is summarized in representative categories in order to obtain meaningful results based on fewer optimizations. Through clustering, 77 % of the existing buildings can be combined into 6 type buildings.

In order to improve the quality of the existing program, a static approach for the calculation of ventilation heat losses implemented in the optimization program is replaced by a dynamic model. The dynamic approach considers influencing factors such as user behaviour, meteorological conditions and building specific elements.

Based on the optimisation results, it can be shown that a reduction of the annual costs by 3 to 25 % is possible in the case of single-family and two-family houses through energetic improvements. In addition, air heat pumps and a greater insulation thickness of the exterior wall are adequate means of reducing greenhouse gas emissions through the low use of monetary funds.

For multy-family houses, the annual costs could be reduced by 40 to 50 %. In this context, combined heat and power units and pellet heating systems were identified as particularly efficient energy generators. In addition, a high savings potential of CO2-emissions through the energetic upgrading of the exterior wall is proven.

The results of this study prove that the energetic refurbishment of existing buildings reduces carbon dioxide emissions as a result of cost optimisation. In addition, there are pareto-optimal solutions for building energy systems for which the emitted greenhouse gases can be significantly reduced at low cost increasment.