Due to rising energy costs, increased public-law and normative requirements for the energy demand of buildings, energy-efficient passive cooling technologies are becoming increasingly important. A comparatively simple form of passive cooling that is possible almost everywhere is night ventilation. It uses the cooling potential of low ambient temperatures at night to cool building structures that are heated during the day. This cooling concept requires a room-by-room supply of outside air, mostly through façade-integrated vents. Microclimatic influences from the building environment and from solar radiation on the façade can lead to a heating of the supply air and thus have a negative effect on the indoor climate or the cooling demand during summer weather phases.

In the context of the present work, the extent to which these external influences cause an increase in intake and thus room temperatures, the effects of the predicted climatic warming and how the night ventilation effectiveness can be optimized by favorable intake and exhaust openings are investigated in rooms with supply air openings integrated into the exterior wall.

Field measurements of eight office buildings will compare various façade and intake designs in terms of their effect on intake and supply air temperatures and identify beneficial designs or design features. Microclimatic influences, e.g. from surrounding buildings or topography, are determined by comparing locally and meteorologically measured weather data.

Parallel to the field measurements, coherent investigations - user-free influences - are carried out at a measurement room on the campus of the University of Wuppertal. A supply air cooling system tested in this context using latent heat storage units proved to be very effective.

Furthermore, formulas for the calculation of intake and supply air temperatures, taking into account solar and wind influences, are derived from the measurement data of the experimental room. The underlying procedures are documented and can be used to derive comparable formulas for other building situations.

The formulas thus obtained are then used in dynamic building simulations to compare the effects of different intake configurations and weather data on the indoor climate and annual cooling energy demand. Taking into account the solar influences on the façade leads to a significantly warmer indoor climate and to an up to 80 % higher cooling energy demand; the heating energy demand, on the other hand, is reduced by up to 20 %. In addition, the simulations show that weather data from meteorological measuring stations are hardly suitable for realistically representing the room temperatures at densely built-up urban locations.

For further analyses, therefore, parameter-based urban effects are imposed on the meteorological data of the test reference year. In various forms, these in combination with data sets of different temperature characteristics form the basis for sensitivity analyses of the indoor climate and the energy demand. Using data from two climate projections, it is determined that by 2050 passive cooling of buildings will only be possible with great technical effort or a combination of different systems. Due to the potentially long service life of buildings, consideration should therefore already be given today when planning new buildings as to how their cooling capacity can be adapted later to the increased requirements.

The heat exchange processes occurring in cooling operation during night ventilation are investigated in detail using transient three-dimensional flow simulations. Particularly efficient ventilation configurations are identified and heat transfer coefficients for use in thermal building simulations are determined and tabulated.

Finally, the results of all the investigations conducted in this thesis are summarized in easy-to-understand design notes and recommendations.

You can obtain the dissertation as a PDF from the University of Wuppertal library (available only in German).

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Since 2019 the EU requires a nationally defined standard for the lowest-energy building for public sector and since 2020 for the private sector. In Germany, the goal of a climate-neutral building stock by 2050 has also been formulated as part of the energy transition. Based on the motivation to reduce energy (costs), climate gas emissions and/or the consumption of resources, buildings with the claim of a balanced energy balance - so-called zero-energy buildings - have already been emerging worldwide for many years. The implementation of these (goals by) zero-energy buildings and the implementation strategies and measures used in practice, the possible methodological specifications within an energy balance (indicators, evaluation procedures, balance limits and frameworks or possible quantification variables) as well as their influence on the building design are analyzed in the course of this work. Energetic and formal trends for the typical and typology-specific implementation of zero-energy buildings are presented.

The dissertation can be obtained as a PDF from the library of the University of Wuppertal (available only in German).

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With the application in student residences, the principle of the passive house, which has been implemented from residential construction to production halls, is applied in a further building typology. The study analyzes several student residences that have been realized as Passive Houses. The subject of the analyses is to determine the application of passive house-typical features, i.e. high-quality thermal insulation of the building envelope, ventilator-supported ventilation with heat recovery and extensive use of internal and solar gains, is presented in the context of this specific usage structure.

You can obtain the dissertation as a PDF from the Bergische Universität library (available only in German).

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The energetic balancing of non-residential buildings usually requires an extensive zoning of the buildings and thus a time-consuming determination of the envelope areas. The subject of this thesis is the development and validation of simplification approaches so that consistent energy planning from the start of planning to building certification can be carried out with reasonable effort, even for complex buildings.

You can obtain the dissertation as a PDF from the Bergische Universität library (available only in German).

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Many of the office buildings that were built 30 to 40 years ago are in need of refurbishment because they are no longer adapted to current needs. Demand arising from usage, economic considerations and adaptations to a change in climate make refurbishment necessary. If there are problems with the indoor climate in summer, passive cooling concepts can improve thermal comfort. Substantial energy savings can be achieved by eliminating active cooling and air conditioning of buildings.

The thesis examines the hypotheses on the one hand through theoretical foundations and on the other hand through case studies and examples. The verification through case studies draws on the two typology buildings as well as on already realized refurbishments from the literature. For the theoretical clarification, topics such as workplace requirements, thermal comfort and possibilities of its assessment, as well as the basic principles of building physics are discussed. This is done from two perspectives: on the one hand, from the overarching viewpoint of general requirements, and on the other hand, with reference to the specific concerns of refurbishment. In addition to the scientific literature, the paper draws on findings obtained in the demonstration projects of the BMWI funding concept "Energy-Optimized Building" (EnOB) with regard to passive cooling and examines the transferability and applicability to building renovation.

Based on a building typology, it is clarified under which conditions a refurbishment with passive cooling measures is reasonable and promising. Criteria for assessing the building's potential for passive cooling can be
be identified on two levels:
- Building-independent factors that either affect the building (climate) or are related to building use (dress code) but do not stem from the building or its design.
- building-related variables (construction method, internal layout).

You can obtain the dissertation as a PDF from the University of Wuppertal library (Available only in German).

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