Master's Thesis David Ole Volkmer

 

Examination of the German Energy Saving Ordinance under both economic and ecological aspects

The federal government has enacted several laws intended to mitigate the climate change
by reducing the primary energy consumption in the future. Since the building sector in the
European Union consumes about 40% of the total energy consumption, the federal government
has released the so-called Energy Saving Ordinance (EnEV). This regulation involves various
requirements concerning the energy consumption and insulation standard of buildings. The
objective of this work is to analyze this ordinance and its development under economical and
ecological aspects.
For this purpose, an optimization model is developed allowing for simultaneous optimization
of building energy systems and envelopes. In order to determine the optimal combination,
the model includes building envelopes with different insulation properties as well as different
conventional and renewable energy and storage systems. The building envelope consists of
the following components: outer walls, roof, floor, interior walls, ceilings and windows. The
energy system can consist of the following components: boiler, electrical heater, heat pump,
cogeneration plant, solar thermal energy and a photovoltaic system. For energy storage it can
choose between a hot water tank and an electrical battery.
Different scenarios are optimized and compared to investigate the potential for improvement
of the EnEV. For these comparisons a single-family house with a living space of 250m2 is
considered. The scenarios investigate for example the influence of different climatic conditions
or certain combinations of the energy system and the building envelope. In each scenario a
Pareto curve is calculated which represents the trade-off solutions between minimizing the
annualized total costs and the CO2-emissions. In all scenarios the model shows that regarding
the minimal costs the building envelope is equipped with the lowest thermal insulation. At the
sama time the heating is covered mainly by a gas boiler and slightly by a solar thermal system.
In addition, a small hot water tank and a photovoltaic system is installed. Regarding the
minimal CO2-emissions only in cold regions the insulation of the building envelope is increased.
However, in most cases the model tends to invest in a modern energy system rather than in
a better insulation. The energy system consists mostly of a large heat pump, a photovoltaic
system and a large hot water tank. In every simulation a photovoltaic system is installed and
is covering between 12−46% of the required electricity. A cogeneration plant is never selected.
One of the remarkable optimizations was the comparison between the scenario in which the
building envelope matched the current EnEV with the scenario without any constraints for the
building envelope. By using modern energy systems and avoiding high thermal insulation, a CO2 reduction of 50% at constant costs or a cost reduction of 5.5% at unchanged CO2-emissions
is possible.
The results of this study show that the investment in a high thermal insulation is mostly
reasonable under ecological and not under economical aspects. As of 2016 the requirements of
the German EnEV require the highest thermal protection for new buildings. However, a much
more economical approach would be to regulate only the greenhouse gas emissions and leave
the decision to the constructor.