1,720,979 research outputs found
The impact of an ideal dynamic building envelope on the energy performance of low energy office buildings
Full text linkThis paper shows the results of a research activity aimed at assessing the advantages of an ideal adaptive building skin over conventional building envelope systems. The basic idea underlying the research consists in imagining an ideal building envelope system characterised by the capability of continuously changing (within a certain range) some of its thermo-physical and optical properties. The reason for the continuous tuning of thermo-physical and optical properties lies in the assumption that an optimised (fixed) configuration, where the properties do not change over time, is not able to minimise the total energy demand of the building at each moment. For the sake of this purpose, an ideal dynamic WWR (Window-to-Wall Ratio) building envelope system for low energy office buildings was modelled and simulated. An integrated thermal-lighting building simulation tool was used. The energy performance of such a system was then analysed and compared against the performance of a conventional façade realised with best-available technologies. The results of the investigation demonstrated the advantages of a dynamic WWR configuration over a static one. However, the improvements achieved in energy demand were lower than expected. This behaviour is strictly related to the configuration of the building used as a reference, which already showed a very high energy performance. Limitations presented by the research method are also briefly pointed out and discussed
Optimizing the configuration of a façade module for office buildings by means of integrated thermal and lighting simulations in a total energy perspective
No full textThe building enclosure plays a relevant role in the management of the energy flows in buildings and in the exploitation of solar energy at a building scale. An optimized configuration of the façade can contribute to reduce the total energy demand of the building. Traditionally, the search for the optimal façade configuration is obtained by analyzing the heating demand and/or the cooling demand only, while the implication of the façade configuration on artificial lighting energy demand is often not addressed. A comprehensive approach (i.e. including heating, cooling and artificial lighting energy demand) is instead necessary to reduce the total energy need of the building and the optimization of the façade configuration becomes no longer straightforward, because non-linear relationships are often disclosed. The paper presents a methodology and the results of the search for the optimal transparent percentage in a façade module for low energy office buildings. The investigation is carried out in a temperate oceanic climate, on the four main orientations, on three versions of the office building and with different HVAC system's efficiency. The results show that, regardless of the orientations and of the façade area of the building, the optimal configuration is achieved when the transparent percentage is between 35% and 45% of the total façade module area. The highest difference between the optimal configuration and the worst one occurs in the north-exposed façade, while the south-exposed façade is the one that shows the smallest difference between the optimal and the worst configuratio
Modelling and validation of a single-storey flexible double-skin façade system with a building energy simulation tool
Full text linkDouble skin facades are adaptive envelopes designed to improve building energy use and comfort performance. Their adaptive principle relies on the dynamic management of the cavity's ventilation flow and, when available, of the shading device. They can also be integrated with the environmental systems for heating, cooling, and ventilation. However, in most cases, the possible exploitation of the ventilation airflow is not fully enabled, as the adoption of only one or two possible airpath limits the possibility that this facade architecture offers, meaning that flexible interaction with the environmental systems cannot be planned. This work aims to develop, using an existing software tool for building energy simulation, a numerical model of a flexible double-skin facade module capable of fully exploiting the adaptive features of such an envelope concept by switching between different cavity ventilation strategies. Leveraging the "Double Glass Facade" component available in IDA ICE, a new model for a flexible double-skin facade module was developed, and its performance in replicating the thermophysical behaviours of such a dynamic system was assessed by comparison with experimental data collected through a dedicated experimental activity using one the outdoor test cells of the TWINS facility in Torino (Italy). The accuracy of the predictions of the new model for a flexible double-skin facade was in line with that obtained by the conventional "Double Glass Facade" component to simulate traditional double-skin facades. The mean bias errors obtained were lower than 1.5 degrees C and 4 W/m2, for air and surface temperature values and for transmitted long-wave or short-wave heat flux values, respectively. By establishing a new archetype model to study the performance and optimal integration of a large class of double-skin facade modules, including fully flexible ones, this work demonstrates the possibility of modifying existing models in building energy simulation tools to study unconventional building envelope model solutions such as adaptive facade systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Relation between daylight availability and electric lighting in a single-family house
Full text linkDaylight availability is an important aspect that can potentially improve both the quality and the energy performance of buildings. However, it is not always straightforward easy to assure that an increase in the daylight availability leads to a reduction of electric energy use for artificial lighting. In this study, experimental measurements and numerical simulations were conducted to analyse the relation between the uses of artificial light and the daylighting availability for different groups of users who lived for one month each in a Zero Emission Building single-family house located in Trondheim, Norway. The use of electric lighting and the outdoor environment conditions (irradiance and illuminance on the horizontal plan) were recorded through advanced daylighting simulations, carried out with DIVA-for-Rhino, the daylighting availability during the periods of occupancy was then reconstructed, using as input data the outdoor environmental variable recorded during the experimental analysis. The results show that the coefficient of correlation between daylight availability and the artificial light is in general low and the use of artificial lighting seems to be largely independent from the availability of natural light
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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