Natural driven ventilation is a widely used technique in hot and arid climate, but it is rarely known that it can lead to significant energy saving in a moderate climate too. In this paper, an existing building is presented that was designed with a passive air conduction system (PACS), where wind and buoyancy effects induce air to be exchanged without external energy needs. The aim is to show that the design methodology, using numerical simulation to give accurate results, is able to use them in further developments. Due to this design process, the specific building possesses numerous special properties, including airflow accelerating elements, solar-heated “chimneys”, and the indoor heat sources coming from the industrial technology. As the building has been constructed and was equipped with around 750 sensors (integrated and manual), it is possible to analyze the ongoing physical phenomenon in a highly detailed way and to collect the experienced dataset for further investigations. The current study carries out a complex validation of the design and the used numerical methods to give general design rules for further PACS design and support following investigations, e.g., occupant comfort prediction or latent heat storage calculation. The experiences showed that the developed computational fluid dynamics technique gives a below 99% accuracy in the velocity and the temperature field, and approximately 85% accuracy in the volume flow values, resulting in a good prediction for aerodynamic characterization of buildings, i.e., passive ventilation air exchange rate.

Buildings are responsible for around 40% of greenhouse emissions globally. The residential building sector is responsible for 24% of energy use. In Hungary, about 800.000 ‘Cube houses’ which date back to the socialist era are still standing. These houses suffer shortages from the energy point of view. This paper presents a new refurbishment approach that attempts to achieve passive cooling with aerodynamic design by integrating the “Venturi disc” which stimulates natural ventilation and night cooling. The work was achieved by using Computational Fluid Dynamics (CFD) simulations using ANSYS Fluent software tool. The implemented building provides lower energy demand and considerably higher comfort in comparison with the typical ‘Cube house’. The building is not only a case study, rather a sustainable model for all the ‘Cube houses’ renewal and further family housing renovations or constructions to reach a higher standard. This paper is a step in an ongoing research project.

New studies and reports are published on a daily basis about the dangers of climate change and its main causes: humanity’s constantly growing population, the built environment and resource consumption. The built environment is responsible for approx. 40% of the total energy consumption, and a significant part comes from maintaining an appropriate indoor comfort environment by heating ventilation and air conditioning. Though contemporary studies have achieved a wide knowledge about natural ventilation and passive air conducting systems (PACS) and their applicability, further investigations are necessary to deepen the aerodynamic topology of air conducting building structures’ shape properties. Hence, in our current research we conducted a series of tests applying different wind catcher geometries. The methodology of this work is based on the authors’ previous work, where passive air conduction systems were compared with different airflow directions via computational fluid dynamic simulations (CFD). After finding the better performing PACS (a downdraught system), this research evaluates whether further improvements in ventilation efficiency are possible due to the aerodynamic shaping of the roof integrated inlet structures. Four different wind catcher geometries were examined to determine the most advantageous dimensional settings in the natural ventilation system’s given boundaries. After multiple series of basic and developed calculation runs, diverse shape designs of the passive air conduction inlet (PACI) were examined, including wind deflector geometries. The initial reference wind catcher’s air change rate was increased by approx. 11%. The results deliver the potential measure of improvements achievable in the aerodynamic shape design of structures under identic conditions of the same building domain. As a consequence, more sophisticated natural ventilation structural solutions will be possible in more operation cost- and performance-effective ways.

A huge portion of energy consumption in buildings comes from heating, ventilation, and air conditioning. Numerous previous works assessed the potential of natural ventilation compared to mechanical ventilation and proved their justification on the field. Nevertheless, it is a major difficulty to collect enough information from the literature to make decisions between different natural ventilation solutions with a given situation and boundary conditions. The current study tests the passive air conduction system (PACS) variations in the design phase of a medium-sized new winery’s cellar and production hall in Villány, Hungary. A computational fluid dynamics simulation based comparative analysis enabled to determine the differences in updraft (UD) and downdraught (DD) PACS, whereby the latter was found to be more efficient. While the DD PACS performed an air change range of 1.02 h−1 to 5.98 h−1, the UD PACS delivered −0.25 h−1 to 12.82 h−1 air change rate. The ventilation performance of the DD version possessed lower amplitudes, but the distribution was more balanced under different wind incident angles, thus this version was chosen for construction. It could be concluded that the DD PACS provides a more general applicability for natural ventilation in moderate climates and in small to medium scale industry hall domains with one in- and one outlet.