TY - JOUR A1 - Völker, Conrad A1 - Mämpel, Silvio A1 - Kornadt, Oliver T1 - Measuring the human body’s micro‐climate using a thermal manikin JF - Indoor Air N2 - The human body is surrounded by a micro‐climate which results from its convective release of heat. In this study, the air temperature and flow velocity of this micro‐climate were measured in a climate chamber at various room temperatures, using a thermal manikin simulating the heat release of the human being. Different techniques (Particle Streak Tracking, thermography, anemometry, and thermistors) were used for measurement and visualization. The manikin surface temperature was adjusted to the particular indoor climate based on simulations with a thermoregulation model (UCBerkeley Thermal Comfort Model). We found that generally, the micro‐climate is thinner at the lower part of the torso, but expands going up. At the head, there is a relatively thick thermal layer, which results in an ascending plume above the head. However, the micro‐climate shape strongly depends not only on the body segment, but also on boundary conditions: the higher the temperature difference between the surface temperature of the manikin and the air temperature, the faster the air flow in the micro‐climate. Finally, convective heat transfer coefficients strongly increase with falling room temperature, while radiative heat transfer coefficients decrease. The type of body segment strongly influences the convective heat transfer coefficient, while only minimally influencing the radiative heat transfer coefficient. KW - Raumklima KW - Mikroklima KW - Wärmeübertragung KW - Strömungsmechanik KW - thermal manikin KW - climate chamber KW - micro climate KW - heat transfer coefficient KW - CFD KW - thermography Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181025-38153 UR - https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12112 N1 - This is the peer reviewed version of the following article: "Measuring the human body’s micro‐climate using a thermal manikin", which has been published in final form at https://doi.org/10.1111/ina.12112. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. IS - 24, 6 SP - 567 EP - 579 ER - TY - JOUR A1 - Völker, Conrad A1 - Kornadt, Oliver A1 - Ostry, Milan T1 - Temperature reduction due to the application of phase change materials JF - Energy and Buildings N2 - Overheating is a major problem in many modern buildings due to the utilization of lightweight constructions with low heat storing capacity. A possible answer to this problem is the emplacement of phase change materials (PCM), thereby increasing the thermal mass of a building. These materials change their state of aggregation within a defined temperature range. Useful PCM for buildings show a phase transition from solid to liquid and vice versa. The thermal mass of the materials is increased by the latent heat. A modified gypsum plaster and a salt mixture were chosen as two materials for the study of their impact on room temperature reduction. For realistic investigations, test rooms were erected where measurements were carried out under different conditions such as temporary air change, alternate internal heat gains or clouding. The experimental data was finally reproduced by dint of a mathematical model. KW - Raumklima KW - Paraffin KW - Phasenumwandlung KW - Gebäude KW - Überhitzung KW - summer overheating in buildings KW - phase change materials KW - PCM KW - Paraffin KW - salt hydrate KW - numerical simulation KW - mathematical model KW - heat storage Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181025-38166 UR - https://www.sciencedirect.com/science/article/pii/S0378778807002034 N1 - The following article appeared in the journal Energy and Buildings 40 (5) 2008, 937‐944 and may be found at https://doi.org/10.1016/j.enbuild.2007.07.008. IS - 40, 5 SP - 937 EP - 944 ER - TY - JOUR A1 - Völker, Conrad A1 - Beckmann, Julia A1 - Koehlmann, Sandra A1 - Kornadt, Oliver T1 - Occupant requirements in residential buildings – an empirical study and a theoretical model JF - Advances in Building Energy Research N2 - Occupant needs with regard to residential buildings are not well known due to a lack of representative scientific studies. To improve the lack of data, a large scale study was carried out using a Post Occupancy Evaluation of 1,416 building occupants. Several criteria describing the needs of occupants were evaluated with regard to their subjective level of relevance. Additionally, we investigated the degree to which deficiencies subjectively exist, and the degree to which occupants were able to accept them. From the data obtained, a hierarchy of criteria was created. It was found that building occupants ranked the physiological needs of air quality and thermal comfort the highest. Health hazards such as mould and contaminated building materials were unacceptable for occupants, while other deficiencies were more likely to be tolerated. Occupant satisfaction was also investigated. We found that most occupants can be classified as satisfied, although some differences do exist between different populations. To explain the relationship between the constructs of what we call relevance, acceptance, deficiency and satisfaction, we then created an explanatory model. Using correlation and regression analysis, the validity of the model was then confirmed by applying the collected data. The results of the study are both relevant in shaping further research and in providing guidance on how to maximize tenant satisfaction in real estate management. KW - Post Occupancy Evaluation KW - Gebäude KW - Benutzung KW - occupant requirements KW - occupant satisfaction KW - residential buildings KW - housing KW - questionnaire Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181015-38137 UR - https://www.tandfonline.com/doi/abs/10.1080/17512549.2012.749808 N1 - This is an Accepted Manuscript of an article published by Taylor & Francis in Advances in Building Energy Research on 29/01/2013, available online: https://www.tandfonline.com/doi/abs/10.1080/17512549.2012.749808. IS - 7 (1) SP - 35 EP - 50 ER - TY - JOUR A1 - Völker, Conrad A1 - Alsaad, Hayder T1 - Simulating the human body's microclimate using automatic coupling of CFD and an advanced thermoregulation model JF - Indoor Air N2 - This study aims to develop an approach to couple a computational fluid dynamics (CFD) solver to the University of California, Berkeley (UCB) thermal comfort model to accurately evaluate thermal comfort. The coupling was made using an iterative JavaScript to automatically transfer data for each individual segment of the human body back and forth between the CFD solver and the UCB model until reaching convergence defined by a stopping criterion. The location from which data are transferred to the UCB model was determined using a new approach based on the temperature difference between subsequent points on the temperature profile curve in the vicinity of the body surface. This approach was used because the microclimate surrounding the human body differs in thickness depending on the body segment and the surrounding environment. To accurately simulate the thermal environment, the numerical model was validated beforehand using experimental data collected in a climate chamber equipped with a thermal manikin. Furthermore, an example of the practical implementations of this coupling is reported in this paper through radiant floor cooling simulation cases, in which overall and local thermal sensation and comfort were investigated using the coupled UCB model. KW - Numerische Strömungssimulation KW - Mikroklima KW - Wärmeübergangszahl KW - Wärmeempfindung KW - computational fluid dynamics KW - microclimate KW - UCB model KW - heat transfer coefficient KW - thermal sensation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20190218-38517 UR - https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12451 N1 - This is the peer reviewed version of the article published in Indoor Air 28 (3), 415-425 (2018) and may be found in final form at https://doi.org/10.1111/ina.12451. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Copyright 2018 John Wiley & Sons. This article may be downloaded for personal use only. Any other use requires prior permission of the authors and John Wiley & Sons. VL - 2018 IS - 28, Heft 3 SP - 415 EP - 425 ER - TY - JOUR A1 - Vogel, Albert A1 - Arnold, Jörg A1 - Voelker, Conrad A1 - Kornadt, Oliver T1 - Data for sound pressure level prediction in lightweight constructions caused by structure-borne sound sources and their uncertainties JF - Data in Brief N2 - When predicting sound pressure levels induced by structure-borne sound sources and describing the sound propagation path through the building structure as exactly as possible, it is necessary to characterize the vibration behavior of the structure-borne sound sources. In this investigation, the characterization of structure-borne sound sources was performed using the two-stage method (TSM) described in EN 15657. Four different structure-borne sound sources were characterized and subsequently installed in a lightweight test stand. The resulting sound pressure levels in an adjacent receiving room were measured. In the second step, sound pressure levels were predicted according to EN 12354-5 based on the parameters of the structure-borne sound sources. Subsequently, the predicted and the measured sound pressure levels were compared to obtain reliable statements on the achievable accuracy when using source quantities determined by TSM with this prediction method. KW - Bauakustik KW - Körperschall KW - building acoustics KW - structure-borne sound KW - sound pressure level prediction KW - structure-borne sound sources KW - OA-Publikationsfonds2023 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20230719-64114 UR - https://www.sciencedirect.com/science/article/pii/S2352340923004110?via%3Dihub VL - 2023 IS - Volume 48, June 2023, article 109292 SP - 1 EP - 16 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Teitelbaum, Eric A1 - Alsaad, Hayder A1 - Aviv, Dorit A1 - Kim, Alexander A1 - Völker, Conrad A1 - Meggers, Forrest A1 - Pantelic, Jovan T1 - Addressing a systematic error correcting for free and mixed convection when measuring mean radiant temperature with globe thermometers JF - Scientific reports N2 - 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. KW - Strahlungstemperatur KW - Mean radiant temperature KW - Globe thermometers KW - Indoor environment KW - Thermal comfort KW - Measurements KW - OA-Publikationsfonds2022 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220509-46363 UR - https://www.nature.com/articles/s41598-022-10172-5#citeas VL - 2022 IS - Volume 12, article 6473 PB - Springer Nature CY - London ER - TY - JOUR A1 - Salandin, Andrea A1 - Arnold, Jörg A1 - Kornadt, Oliver T1 - Noise in an intensive care unit JF - The Journal of the Acoustical Society of America N2 - Patients and staff in hospitals are exposed to a complex sound environment with rather high noise levels. In intensive care units, the main noise sources are hospital staff on duty and medical equipment, which generates both operating noise and acoustic alarms. Although noise in most cases is produced during activities for the purpose of saving life, noise can induce significant changes in the depth and quality of sleep and negatively affect health in general. Results of a survey of hospital staff are presented as well as measurements in two German hospital wards: a standard two-bed room and a special Intermediate Care Unit (IMC-Unit), each in a different Intensive Care Unit (ICU). Sound pressure data were collected over a 48 hour period and converted into different levels (LAFeq, LAFmax, LAFmin, LAF 5%), as well as a rating level LAr, which is used to take tonality and impulsiveness into account. An analysis of the survey and the measured data, together with a comparison of thresholds of national and international regulations and standards describe the acoustic situation and its likely noise effects on staff and patients. KW - Lärm KW - Messung KW - Akustik KW - Intensivstation KW - Arbeitsplatz KW - noise KW - intensive care unit KW - acoustical measurement KW - Lärm KW - Intensivstation Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170713-32649 UR - http://dx.doi.org/10.1121/1.3655884 N1 - Copyright 2011 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America. The following article appeared in The Journal of the Acoustical Society of America 130, 3754 (2011) and may be found at http://dx.doi.org/10.1121/1.3655884. VL - 2011 IS - 130 (6) SP - 3754 EP - 3760 ER - TY - JOUR A1 - Pollack, Moritz A1 - Lück, Andrea A1 - Wolf, Mario A1 - Kraft, Eckhard A1 - Völker, Conrad T1 - Energy and Business Synergy: Leveraging Biogenic Resources from Agriculture, Waste, and Wastewater in German Rural Areas JF - Sustainability N2 - 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. KW - Energiewende KW - Energieplanung KW - Abfallwirtschaft KW - organischer Abfall KW - Biomasse KW - Regionalentwicklung KW - biogene Abfallstoffe KW - Abwassermanagement KW - OA-Publikationsfonds2023 Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20231222-65172 UR - https://www.mdpi.com/2071-1050/15/24/16573 VL - 2023 IS - volume 15, issue 24, article 16573 SP - 1 EP - 25 PB - MDPI CY - Basel ER - TY - JOUR A1 - Gena, Amayu Wakoya A1 - Völker, Conrad A1 - Settles, Gary T1 - Qualitative and quantitative schlieren optical measurement of the human thermal plume JF - Indoor Air N2 - A new large‐field, high‐sensitivity, single‐mirror coincident schlieren optical instrument has been installed at the Bauhaus‐Universität Weimar for the purpose of indoor air research. Its performance is assessed by the non‐intrusive measurement of the thermal plume of a heated manikin. The schlieren system produces excellent qualitative images of the manikin's thermal plume and also quantitative data, especially schlieren velocimetry of the plume's velocity field that is derived from the digital cross‐correlation analysis of a large time sequence of schlieren images. The quantitative results are compared with thermistor and hot‐wire anemometer data obtained at discrete points in the plume. Good agreement is obtained, once the differences between path‐averaged schlieren data and planar anemometry data are reconciled. KW - Raumklima KW - Behaglichkeit KW - Digital image correlation KW - human thermal plume KW - schlieren imaging KW - schlieren velocimetry KW - thermal comfort KW - Schlierenspiegel Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20200709-41936 UR - https://onlinelibrary.wiley.com/doi/full/10.1111/ina.12674 VL - 2020 IS - volume 30, issue 4 SP - 757 EP - 766 PB - John Wiley & Sons ER - TY - JOUR A1 - Dokhanchi, Najmeh Sadat A1 - Arnold, Jörg A1 - Vogel, Albert A1 - Völker, Conrad T1 - Measurement of indoor air temperature distribution using acoustic travel-time tomography: Optimization of transducers location and sound-ray coverage of the room JF - Measurement N2 - 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. KW - Bauphysik KW - Bauklimatik KW - Akustische Laufzeit-Tomographie Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20220524-46473 UR - https://www.sciencedirect.com/science/article/abs/pii/S0263224120304723?via%3Dihub VL - 2020 IS - Volume 164, article 107934 PB - Elsevier CY - Amsterdam ER -