31. Improved understanding of thermal comfort could yield energy savings in heritage buildingsKatja Žagar, Uroš Bohinc, Blaž Kurent, Katja Malovrh Rebec, 2024, published scientific conference contribution Abstract: It is necessary to improve the understanding of thermal comfort to reduce energy consumption for heating and cooling in heritage buildings, which are often energy inefficient and where interventions are limited. Personal thermal comfort models based on measurements of environmental conditions and the individual's physiological and subjective responses represent a potential solution to ensure the optimization of existing systems. Past research shows that lighting could impact thermophysiology and subjective perception of thermal conditions, but it is not clear whether the impact is sufficient to make light adaptation an appropriate solution to reduce energy consumption in heritage buildings, where people live and work. The research conducted under realistic semi-controlled conditions in an office environment of an existing building addresses this research gap. The paper presents the first partial simplified analyses and preliminary results of a wider ongoing study, mainly showing a correlation between skin temperature and air temperature and a partially promising effect of light on subjective thermal perception. Our research on the effect of light on thermal comfort does not provide definitive conclusions but rather highlights the need for further investigation in actual heritage buildings.
Keywords: heritage buildings, minimal intervention renovation, thermal comfort, light
Published in DiRROS: 19.12.2024; Views: 43; Downloads: 14
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32. High-Intensity Fast-Response Electric radiant Panel (HIFREP) for increased accuracy on thermal boundary conditions during fire testingFlorian Put, Balša Jovanović, Evelien Symoens, Andrea Lucherini, Bart Merci, Ruben Van Coile, 2024, published scientific conference contribution Abstract: Fire resistance tests rely on the use of standardized furnaces to apply specific thermal boundary conditions to assess the performance of construction materials and systems in fire conditions. However, these tests are very expensive and encounter challenges related to repeatability and uncertainties in establishing thermal boundary conditions. Moreover, their incapacitance to tailor experiments hinders advancements in understanding structural behaviour during fire exposure. In this work, a novel type of radiant panel, that operates on electricity, is introduced: the High-Intensity Fast-Response Electric radiant Panel (HIFREP). This innovation offers enhanced sustainability performance while ensuring more precise control over thermal boundary conditions. By eliminating the need for gas combustion, the panel can be used in a traditional structural testing lab to investigate non-combustible materials (e.g. concrete), without requiring extraction hoods and other provisions. The presented electric radiant panel system represents a significant step forward from fire resistance furnace testing.
Keywords: radiant panel, fire testing, heat transfer, radiation, heat flux, fire safety, thermal boundary conditions
Published in DiRROS: 19.12.2024; Views: 40; Downloads: 17
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33. Predicting the total wall time of CFD simulations of single-compartment firesMartin Veit, Andrea Lucherini, Georgios Maragkos, Bart Merci, 2024, published scientific conference contribution Abstract: The total wall time is often difficult to predict a priori in compartment fire simulations due to dynamic phenomena that can occur, e.g., flame extinction. The wall time is dependent on multiple physical factors in the simulation, along with simulation factors and the system used to compute the model. Specifically, the CFL number of a simulation is highly influential to the wall time, as this restricts the time step size. In this paper, the prediction of the total wall time for a single-compartment fire is investigated considering varying fire heat release rates and compartment ventilation factors. It is shown that an increasing heat release rate increases the total wall time due to higher velocities inside the compartment. Furthermore, when the compartment becomes under-ventilated, the wall time becomes more difficult to predict early on in the simulation, as steady state conditions are reached later, compared to well-ventilated cases. The time at which the wall time can be accurately predicted changed from a few physical seconds in the well-ventilated case, to up to 60 physical seconds for the under-ventilated case.
Keywords: simulations, computational fluid dynamics, fire dynamics simulator, wall time
Published in DiRROS: 19.12.2024; Views: 39; Downloads: 14
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39. Delavnica »Biotehnični ukrepi v gozdnatih hudourniških območjih« na Gozdarskem inštitutu SlovenijeUrša Vilhar, Tomaž Cej, Klemen Jerina, Tadej Jeršič, Erika Kozamernik, Jože Papež, Robert Robek, Jaša Saražin, 2024, professional article Keywords: urejanje hudournikov, Slovenija
Published in DiRROS: 18.12.2024; Views: 53; Downloads: 19
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40. Kekulé structure of angularly connected even ring systemsSimon Brezovnik, 2024, original scientific article Abstract: An even ring system $G$ is a simple $2$-connected plane graph with all interior vertices of degree $3$, all exterior vertices of either degree $2$ or $3$, and all finite faces of an even length. $G$ is angularly connected if all of the peripheral segments of $G$ have odd lengths. In this paper, we show that every angularly connected even ring system $G$, which does not contain any triple of altogether-adjacent peripheral faces, has a perfect matching. This was achieved by finding an appropriate edge coloring of $G$, derived from the proof of the existence of a proper face $3$-coloring of the graph. Additionally, an infinite family of graphs that are face $3$-colorable has been identified. When interpreted in the context of the inner dual of $G$, this leads to the introduction of $3$-colorable graphs containing cycles of lengths $4$ and $6$, which is a supplementation of some already known results. Finally, we have investigated the concept of the Clar structure and Clar set within the aforementioned family of graphs. We found that a Clar set of an angularly connected even ring system cannot in general be obtained by minimizing the cardinality of the set $A$. This result is in contrast to the previously known case for the subfamily of benzenoid systems, which admit a face $3$-coloring. Our results open up avenues for further research into the properties of Clar and Fries sets of angularly connected even ring systems.
Keywords: Kekulé structure, Clar structure, perfect matching, benzenoid system, even ring system, face coloring, edge coloring, Clar set
Published in DiRROS: 18.12.2024; Views: 41; Downloads: 14
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