1,721,016 research outputs found
Integrated numerical and experimental methodology for thermal-energy analysis and optimization of heritage museum buildings
No full textResearch effort was dedicated to the analysis of museums microclimate for the preservation of artifacts and indoor environment. In this paper, continuous monitoring and dynamic simulation of an ancient exhibition site are carried out to evaluate indoor microclimate and energy performance. The aim is to develop a multidisciplinary methodology for preserving artworks and historic buildings in the view of sustainability and comfort. The paper also shows how the environmental conditions of two thermal zones different for geometry, occupancy, ventilation rate, and heating, ventilation, and air conditioning (HVAC) systems are far from the values suggested by the regulations for the preservation of artifacts and from human comfortable set points of temperature and relative humidity. This work highlights the need for further investigation of historical exposition sites to reduce artworks' damaging and occupants' environmental stress. Practical application: Many historical buildings in European countries host exhibition sites. Indoor microclimate of such areas is often inappropriate for visitors' comfort, for artworks', and building preservation. In fact, usually HVAC systems operate according to simple temperature-based control protocols. This study shows how old architectures could present indoor environmental conditions far from the target, for artworks' preservation, for occupants' comfort, and for the building maintenance. This paper presents a numerical-experimental methodology applied to an architectural heritage. The analysis gives insight on this issue, and could guide building operators and service management to investigate and optimize indoor environmental conditions where artworks are preserved
Experimental analysis of natural gravel covering as cool roof and cool pavement
No full textBuilding energy efficiency has become a key research issue in the last years, given the huge energy requirement of the construction sector and the potential for energy saving. In particular, passive solutions such as natural materials are always appreciated for their intrinsic high thermal performance and low environmental impact. In this view, natural stones represent a good solution as building envelope covering or city pavements. This paper concerns the experimental characterization of several gravel coverings for roofs and urban paving in terms of their albedo characteristics. A cheap and local natural high reflectance stone is chosen, which common use is as aggregate for concrete. The purpose of the work is to study its intrinsic cooling potential. To this aim, the in-field albedo of gravel samples is measured with varying grain size of the same natural stone named “Bargiolina”. These in-field measurements are compared to in-lab measurements about solar reflectance and thermal emissivity. The analysis shows a significant variation of the albedo with varying grain size of the same stone. Both in-lab and in-field measurements agree that the stone with the smallest grain size, i.e. thin sand, has the best optic-thermal performance in terms of solar reflectance (62%). This feature results in the reduction of the surface temperature when exposed to solar radiation. Moreover, a natural mixed stone is compared to the high reflectance stone, demonstrating that the chosen “Bargiolina” presents an intrinsic cool behavior. Therefore, this natural, low-cost, low impact and high performance material could be successfully applied as cool roof or cool paving, for its passive cooling contribution and its potential for reducing urban heat islands
Thermal-energy analysis of natural "cool" stone aggregates as passive cooling and global warming mitigation technique
No full textRecently, research focused on the development of roofing and paving systems aimed at (i) enhancing the passive cooling at single-building
level and (ii) mitigating urban heat island at inter-building scale. In this work, the optic-thermal behavior of a naturally cool gravel for
roof and paving application is studied, through lab and field experimental analyses. Specific evaluation about the cooling potential is
carried out with varying grain size of the same gravel and stone typology. Additionally, its cool roof effect is investigated through
dynamic simulation in a case study university campus in Italy. Finally, the analysis of the global warming contribution of the gravel
was performed, with reference to the most performing gravel size. The results show differences up to 24% in terms of albedo with
varying the only grain size. Additionally, the gravel with the smallest grain size resulted the most performing in terms of summer energy
saving and indoor thermal comfort. By shifting from single building scale models to global climate energy balance models, an equivalent
carbon emission offset of 4400 tCO2eq was found, imputable to the (i) energy saving contribution, and (ii) global warming mitigation effect
produced by the enhanced albedo of the case study area
Experimental in-lab and in-field analysis of waterproof membranes for cool roof application and urban heat island mitigation
No full textBuildings are responsible for about the 40% of the global annual energy consumption, therefore, innovative strategies for buildings' energy efficiency are under development. Strategies of re-roofing with "cool" materials have a non-negligible cooling energy saving potential, as they contribute to the reduction of the peak ambient temperatures during summer and, moreover, they contribute to the improvement of the urban microclimate by decreasing the intensity of heat island phenomena. In this paper, the experimental characterization and optimization of a new membrane for buildings' roof is carried out. To this aim, laboratory measurements were performed to determine its optic-energy properties and, therefore, to optimize its "cool roof" behavior. A full scale field test was also setup in order to measure the global solar radiation reflected by each membrane, before and after optimization, with varying boundary conditions, e.g. time during the day, seasonal period, and weather conditions. The in-field experimental campaign allowed to characterize the optic-energy behavior of the cool membranes in real boundary conditions, showing non-negligible variation of measured solar reflection capability with varying environmental constraints in winter conditions. The research showed interesting results from the in-lab optimization campaign, and non-negligible unreliability due to environmental agents affecting in-field albedo measurement
Outdoor thermal and visual perception of natural cool materials for roof and urban paving
Get PDFGiven the acknowledged thermal performance of natural light color gravels applied as cool roof and cool urban paving, this work is aimed at investigating if such behavior is perceivable by pedestrians, who are questioned in this paper about their visual and thermal comfort perception. In fact, there are still related aspects to analyze, in order to optimize their application and provide a comfortable space for users, both on the thermal and the visual point of view. Therefore, the question that this work wants to answer is: given their intrinsic characteristics, do these materials create a sensitive thermally and visually more comfortable environment for pedestrians? In order to address this uninvestigated issue, users’ judgment about visual and thermal comfort of these surfaces is considered, also by comparing them with grassland and asphalt. Also, the statistical correspondence between physical properties of such materials and possible correspondence with respect to human perception with varying weather conditions is analyzed. Given the relatively high reflectance of these materials, it appears particularly important to evaluate these aspects, to consciously apply them as urban paving or roof covering by optimizing their natural passive cooling potential. In this preliminary study, users’ response to these surfaces is evaluated by mean of field surveys, both on the thermal and the visual evaluation, and contemporary in-field measurements of surface parameters. Also, human perception with respect to these high-reflectance surfaces’ is compared with the one related to grassland and asphalt, with varying weather conditions. Then, a statistical analysis is performed to investigate the differences among different gravels, grassland and asphalt, based on surveys’ results. The results show how pedestrians, questioned during summer days, prefer grassland, while asphalt is the less favorite surface both visually and thermally; there is a small difference between gravels’ types evaluation, while weather variability affect the preferences
Modeling of urban canyon: analytical and experimental remarks
No full textThe urban climate of high-density areas is often affected by an increase of the air temperature known as Urban Heat Island (UHI) phenomenon. UHI is strongly influenced by the solar reflectance of conventional materials used for building envelope and urban coatings, i.e. streets and square pavings. The present work proposes an original method to predict the temperature of both facades and local air mass on urban scenarios. The effect of changes on coatings may also be estimated. The proposed method is based on an Experimental Facility (EF) and a Theoretical Model (TM) which are jointly taken into account for UHI predictions. EF is located at the University of Perugia which is composed of two separate metal rails incorporating several insulating frames, resembling a urban canyon, positioned at different mutual height/distance ratios (i.e. H/D = 0.5, 1.0, 2.0). Each frame can be equipped with particular reflective films (e.g. cool roofs coatings) in order to assess variation of radiative exchanges as a function of geometry, meteorological conditions, and radiative properties of walls. The monitoring system is equipped with temperature sensors, a pyranometer and an anemometer. A weather station is located nearby. EF may be used directly to estimate UHI by a mechanical analogy which however introduces strong limitation on real scenario dimensions and operative conditions. By validating the TM via EF the range of real scenario may be studied and predicted is widely extended and the proposed method may be applied virtually for any case. The preliminary calibration of the methodology using measured data is also presented
Article Experimental Analysis of Natural Gravel Covering as Cool Roofing and Cool Pavement
No full textwww.mdpi.com/journal/sustainabilit
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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