@article{PollackLueckWolfetal.,
  author    = {Pollack, Moritz and L{\"u}ck, Andrea and Wolf, Mario and Kraft, Eckhard and V{\"o}lker, Conrad},
  title     = {Energy and Business Synergy: Leveraging Biogenic Resources from Agriculture, Waste, and Wastewater in German Rural Areas},
  series = {Sustainability},
  volume    = {2023},
  journal   = {Sustainability},
  number    = {volume 15, issue 24, article 16573},
  publisher = {MDPI},
  address   = {Basel},
  doi       = {10.3390/su152416573},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20231222-65172},
  pages     = {1 -- 25},
  abstract  = {The imperative to transform current energy provisions is widely acknowledged. However, scant attention has hitherto been directed toward rural municipalities and their innate resources, notably biogenic resources. In this paper, a methodological framework is developed to interconnect resources from waste, wastewater, and agricultural domains for energy utilization. This entails cataloging existing resources, delineating their potential via quantitative assessments utilizing diverse technologies, and encapsulating them in a conceptual model. The formulated models underwent iterative evaluation with engagement from diverse stakeholders. Consequently, 3 main concepts, complemented by 72 sub-concepts, were delineated, all fostering positive contributions to climate protection and providing heat supply in the rural study area. The outcomes' replicability is underscored by the study area's generic structure and the employed methodology. Through these inquiries, a framework for the requisite energy transition, with a pronounced emphasis on the coupling of waste, wastewater, and agriculture sectors in rural environments, is robustly analyzed.},
  subject      = {Energiewende},
  language  = {en}
}
@article{AlsaadHartmannVoelker,
  author    = {Alsaad, Hayder and Hartmann, Maria and V{\"o}lker, Conrad},
  title     = {Hygrothermal simulation data of a living wall system for decentralized greywater treatment},
  series = {Data in Brief},
  volume    = {2022},
  journal   = {Data in Brief},
  number    = {volume 40, article 107741},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.dib.2021.107741},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220106-45483},
  pages     = {12},
  abstract  = {This dataset presents the numerical analysis of the heat and moisture transport through a facade equipped with a living wall system designated for greywater treatment. While such greening systems provide many environmental benefits, they involve pumping large quantities of water onto the wall assembly, which can increase the risk of moisture in the wall as well as impaired energetic performance due to increased thermal conductivity with increased moisture content in the building materials. This dataset was acquired through numerical simulation using the coupling of two simulation tools, namely Envi-Met and Delphin. This coupling was used to include the complex role the plants play in shaping the near-wall environmental parameters in the hygrothermal simulations. Four different wall assemblies were investigated, each assembly was assessed twice: with and without the living wall. The presented data include the input and output parameters of the simulations, which were presented in the co-submitted article [1].},
  subject      = {Kupplung},
  language  = {en}
}
@article{TeitelbaumAlsaadAvivetal.,
  author    = {Teitelbaum, Eric and Alsaad, Hayder and Aviv, Dorit and Kim, Alexander and V{\"o}lker, Conrad and Meggers, Forrest and Pantelic, Jovan},
  title     = {Addressing a systematic error correcting for free and mixed convection when measuring mean radiant temperature with globe thermometers},
  series = {Scientific reports},
  volume    = {2022},
  journal   = {Scientific reports},
  number    = {Volume 12, article 6473},
  publisher = {Springer Nature},
  address   = {London},
  doi       = {10.1038/s41598-022-10172-5},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220509-46363},
  pages     = {18},
  abstract  = {It is widely accepted that most people spend the majority of their lives indoors. Most individuals do not realize that while indoors, roughly half of heat exchange affecting their thermal comfort is in the form of thermal infrared radiation. We show that while researchers have been aware of its thermal comfort significance over the past century, systemic error has crept into the most common evaluation techniques, preventing adequate characterization of the radiant environment. Measuring and characterizing radiant heat transfer is a critical component of both building energy efficiency and occupant thermal comfort and productivity. Globe thermometers are typically used to measure mean radiant temperature (MRT), a commonly used metric for accounting for the radiant effects of an environment at a point in space. In this paper we extend previous field work to a controlled laboratory setting to (1) rigorously demonstrate that existing correction factors used in the American Society of Heating Ventilation and Air-conditioning Engineers (ASHRAE) Standard 55 or ISO7726 for using globe thermometers to quantify MRT are not sufficient; (2) develop a correction to improve the use of globe thermometers to address problems in the current standards; and (3) show that mean radiant temperature measured with ping-pong ball-sized globe thermometers is not reliable due to a stochastic convective bias. We also provide an analysis of the maximum precision of globe sensors themselves, a piece missing from the domain in contemporary literature.},
  subject      = {Strahlungstemperatur},
  language  = {en}
}
@article{AlsaadHartmannHilbeletal.,
  author    = {Alsaad, Hayder and Hartmann, Maria and Hilbel, Rebecca and V{\"o}lker, Conrad},
  title     = {ENVI-met validation data accompanied with simulation data of the impact of facade greening on the urban microclimate},
  series = {Data in Brief},
  volume    = {2022},
  journal   = {Data in Brief},
  number    = {Volume 42, article 108200},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.dib.2022.108200},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220511-46455},
  pages     = {1 -- 13},
  abstract  = {This dataset consists mainly of two subsets. The first subset includes measurements and simulation data conducted to validate the simulation tool ENVI-met. The measurements were conducted at the campus of the Bauhaus-University Weimar in Weimar, Germany and consisted of recording exterior air temperature, globe temperature, relative humidity, and wind velocity at 1.5 m at four points on four different days. After the measurements, the geometry of the campus was modelled and meshed; the simulations were conducted using the weather data of the measurements days with the aim of investigating the accuracy of the model. The second data subset consists of ENVI-met simulation data of the potential of facade greening in improving the outdoor environment and the indoor air temperature during heatwaves in Central European cities. The data consist of the boundary conditions and the simulation output of two simulation models: with and without facade greening. The geometry of the models corresponded to a residential buildings district in Stuttgart, Germany. The simulation output consisted of exterior air temperature, mean radiant temperature, relative humidity, and wind velocity at 12 different probe points in the model in addition to the indoor air temperature of an exemplary building. The dataset presents both vertical profiles of the probed parameters as well as the time series output of the five-day simulation duration. Both data subsets correspond to the investigations presented in the co-submitted article [1].},
  subject      = {Messung},
  language  = {en}
}
@article{AlsaadVoelker,
  author    = {Alsaad, Hayder and V{\"o}lker, Conrad},
  title     = {Qualitative evaluation of the flow supplied by personalized ventilation using schlieren imaging and thermography},
  series = {Building and Environment},
  volume    = {2020},
  journal   = {Building and Environment},
  number    = {Volume 167, article 106450},
  publisher = {Elsevier},
  address   = {New York},
  doi       = {10.25643/bauhaus-universitaet.4511},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20211008-45117},
  pages     = {11},
  abstract  = {Personalized ventilation (PV) is a mean of delivering conditioned outdoor air into the breathing zone of the occupants. This study aims to qualitatively investigate the personalized flows using two methods of visualization: (1) schlieren imaging using a large schlieren mirror and (2) thermography using an infrared camera. While the schlieren imaging was used to render the velocity and mass transport of the supplied flow, thermography was implemented to visualize the air temperature distribution induced by the PV. Both studies were conducted using a thermal manikin to simulate an occupant facing a PV outlet. As a reference, the flow supplied by an axial fan and a cased axial fan was visualized with the schlieren system as well and compared to the flow supplied by PV. Schlieren visualization results indicate that the steady, low-turbulence flow supplied by PV was able to penetrate the thermal convective boundary layer encasing the manikin's body, providing clean air for inhalation. Contrarily, the axial fan diffused the supplied air over a large target area with high turbulence intensity; it only disturbed the convective boundary layer rather than destroying it. The cased fan supplied a flow with a reduced target area which allowed supplying more air into the breathing zone compared to the fan. The results of thermography visualization showed that the supplied cool air from PV penetrated the corona-shaped thermal boundary layer. Furthermore, the supplied air cooled the surface temperature of the face, which indicates the large impact of PV on local thermal sensation and comfort.},
  subject      = {Bildverarbeitung},
  language  = {en}
}
@article{BecherGenaAlsaadetal.,
  author    = {Becher, Lia and Gena, Amayu Wakoya and Alsaad, Hayder and Richter, Bernhard and Spahn, Claudia and V{\"o}lker, Conrad},
  title     = {The spread of breathing air from wind instruments and singers using schlieren techniques},
  series = {Indoor Air},
  volume    = {2021},
  journal   = {Indoor Air},
  number    = {volume 31, issue 6},
  publisher = {Wiley Blackwell},
  address   = {Oxford},
  doi       = {10.1111/ina.12869},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220209-45817},
  pages     = {1798 -- 1814},
  abstract  = {The spread of breathing air when playing wind instruments and singing was investigated and visualized using two methods: (1) schlieren imaging with a schlieren mirror and (2) background-oriented schlieren (BOS). These methods visualize airflow by visualizing density gradients in transparent media. The playing of professional woodwind and brass instrument players, as well as professional classical trained singers were investigated to estimate the spread distances of the breathing air. For a better comparison and consistent measurement series, a single high note, a single low note, and an extract of a musical piece were investigated. Additionally, anemometry was used to determine the velocity of the spreading breathing air and the extent to which it was quantifiable. The results showed that the ejected airflow from the examined instruments and singers did not exceed a spreading range of 1.2 m into the room. However, differences in the various instruments have to be considered to assess properly the spread of the breathing air. The findings discussed below help to estimate the risk of cross-infection for wind instrument players and singers and to develop efficacious safety precautions, which is essential during critical health periods such as the current COVID-19 pandemic.},
  subject      = {Covid-19},
  language  = {en}
}
@article{DokhanchiArnoldVogeletal.2020,
  author    = {Dokhanchi, Najmeh Sadat and Arnold, J{\"o}rg and Vogel, Albert and V{\"o}lker, Conrad},
  title     = {Measurement of indoor air temperature distribution using acoustic travel-time tomography: Optimization of transducers location and sound-ray coverage of the room},
  series = {Measurement},
  volume    = {2020},
  journal   = {Measurement},
  number    = {Volume 164, article 107934},
  publisher = {Elsevier},
  address   = {Amsterdam},
  doi       = {10.1016/j.measurement.2020.107934},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220524-46473},
  year      = {2020},
  abstract  = {Acoustic travel-time TOMography (ATOM) allows the measurement and reconstruction of air temperature distributions. Due to limiting factors, such as the challenge of travel-time estimation of the early reflections in the room impulse response, which heavily depends on the position of transducers inside the measurement area, ATOM is applied mainly outdoors. To apply ATOM in buildings, this paper presents a numerical solution to optimize the positions of transducers. This optimization avoids reflection overlaps, leading to distinguishable travel-times in the impulse response reflectogram. To increase the accuracy of the measured temperature within tomographic voxels, an additional function is employed to the proposed numerical method to minimize the number of sound-path-free voxels, ensuring the best sound-ray coverage of the room. Subsequently, an experimental set-up has been performed to verify the proposed numerical method. The results indicate the positive impact of the optimal positions of transducers on the distribution of ATOM-temperatures.},
  subject      = {Bauphysik},
  language  = {en}
}
@article{BecherVoelkerRodehorstetal.,
  author    = {Becher, Lia and V{\"o}lker, Conrad and Rodehorst, Volker and Kuhne, Michael},
  title     = {Background-oriented schlieren technique for two-dimensional visualization of convective indoor air flows},
  series = {Optics and Lasers in Engineering},
  volume    = {2020},
  journal   = {Optics and Lasers in Engineering},
  number    = {Volume 134, article 106282},
  doi       = {https://doi.org/10.1016/j.optlaseng.2020.106282},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20220810-46972},
  pages     = {9},
  abstract  = {This article focuses on further developments of the background-oriented schlieren (BOS) technique to visualize convective indoor air flow, which is usually defined by very small density gradients. Since the light rays deflect when passing through fluids with different densities, BOS can detect the resulting refractive index gradients as integration along a line of sight. In this paper, the BOS technique is used to yield a two-dimensional visualization of small density gradients. The novelty of the described method is the implementation of a highly sensitive BOS setup to visualize the ascending thermal plume from a heated thermal manikin with temperature differences of minimum 1 K. To guarantee steady boundary conditions, the thermal manikin was seated in a climate laboratory. For the experimental investigations, a high-resolution DLSR camera was used capturing a large field of view with sufficient detail accuracy. Several parameters such as various backgrounds, focal lengths, room air temperatures, and distances between the object of investigation, camera, and structured background were tested to find the most suitable parameters to visualize convective indoor air flow. Besides these measurements, this paper presents the analyzing method using cross-correlation algorithms and finally the results of visualizing the convective indoor air flow with BOS. The highly sensitive BOS setup presented in this article complements the commonly used invasive methods that highly influence weak air flows.},
  subject      = {Raumklima},
  language  = {en}
}
@article{AlsaadVoelker,
  author    = {Alsaad, Hayder and V{\"o}lker, Conrad},
  title     = {Der K{\"u}hlungseffekt der personalisierten L{\"u}ftung},
  series = {Bauphysik},
  volume    = {2020},
  journal   = {Bauphysik},
  number    = {volume 42, issue 5},
  publisher = {Ernst \& Sohn bei John Wiley \& Sons},
  address   = {Hoboken},
  doi       = {10.25643/bauhaus-universitaet.4272},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20201020-42723},
  pages     = {218 -- 225},
  abstract  = {Personalisierte L{\"u}ftung (PL) kann die thermische Behaglichkeit sowie die Qualit{\"a}t der eingeatmeten Atemluft verbessern, in dem jedem Arbeitsplatz Frischluft separat zugef{\"u}hrt wird. In diesem Beitrag wird die Wirkung der PL auf die thermische Behaglichkeit der Nutzer unter sommerlichen Randbedingungen untersucht. Hierf{\"u}r wurden zwei Ans{\"a}tze zur Bewertung des K{\"u}hlungseffekts der PL untersucht: basierend auf (1) der {\"a}quivalenten Temperatur und (2) dem thermischen Empfinden. Grundlage der Auswertung sind in einer Klimakammer gemessene sowie numerisch simulierte Daten. Vor der Durchf{\"u}hrung der Simulationen wurde das numerische Modell zun{\"a}chst anhand der gemessenen Daten validiert. Die Ergebnisse zeigen, dass der Ansatz basierend auf dem thermischen Empfinden zur Evaluierung des K{\"u}hlungseffekts der PL sinnvoller sein kann, da bei diesem die komplexen physiologischen Faktoren besser ber{\"u}cksichtigt werden.},
  subject      = {L{\"u}ftung},
  language  = {de}
}
@article{AlsaadVoelker,
  author    = {Alsaad, Hayder and V{\"o}lker, Conrad},
  title     = {Performance evaluation of ductless personalized ventilation in comparison with desk fans using numerical simulations},
  series = {Indoor Air},
  volume    = {2020},
  journal   = {Indoor Air},
  publisher = {John Wiley \& Sons Ltd},
  doi       = {10.1111/ina.12672},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20200422-41407},
  pages     = {14},
  abstract  = {The performance of ductless personalized ventilation (DPV) was compared to the performance of a typical desk fan since they are both stand-alone systems that allow the users to personalize their indoor environment. The two systems were evaluated using a validated computational fluid dynamics (CFD) model of an office room occupied by two users. To investigate the impact of DPV and the fan on the inhaled air quality, two types of contamination sources were modelled in the domain: an active source and a passive source. Additionally, the influence of the compared systems on thermal comfort was assessed using the coupling of CFD with the comfort model developed by the University of California, Berkeley (UCB model). Results indicated that DPV performed generally better than the desk fan. It provided better thermal comfort and showed a superior performance in removing the exhaled contaminants. However, the desk fan performed better in removing the contaminants emitted from a passive source near the floor level. This indicates that the performance of DPV and desk fans depends highly on the location of the contamination source. Moreover, the simulations showed that both systems increased the spread of exhaled contamination when used by the source occupant.},
  subject      = {Behaglichkeit},
  language  = {en}
}