1,720,960 research outputs found
Comparison of Different Glare Indices through Metrics for Long Term and Zonal Visual Comfort Assessment
Full text linkNowadays different indices are used for the assessment of the visual discomfort related to glare, such as Daylight Glare Index, Daylight Glare Probability, and Vertical Eye illuminance. Regardless of their effectiveness in detecting glare perception, all these indices are intended to be local and instantaneous, not summarizing the long term glare perception through the space (Carlucci et al. 2015). In this work, a set of metrics able to express both the time constancy, i.e. availability, and the spatial uniformity, i.e. usability, has been used for detecting discrepancies and inconsistencies between the glare indices when dealing with time and space distribution. Results confirm that different glare indices can lead to different conclusions not only when considering point and instantaneous values but also when analysing availability and usability. Moreover, the availability and usability representations, indirectly confirm themselves effective in providing a global assessment of the confined space analysed, even when visual comfort is concerned
On the global performance of offices with different Complex Fenestration Systems
No full textComplex fenestration systems influence indoor comfort conditions and energy consumption in a complex way. If all the involved aspects are not considered jointly since the design phase, buildings can show a deep gap between their planned and real performance, especially when dealing with low energy buildings (Vanhoutteghem et al., 2015). This can be avoided by identifying the design configurations able to provide a trade-off between contrasting requisites: improving comfort conditions while minimizing energy use. This work analyzes and compares different design solutions for an open space office from a global performance perspective. Dependence on the building characteristics and operation strategy has been assessed by comparing two different windows sizes, three glazing systems, and three different approaches to control the shading devices, for a South oriented façade in the climate of Rome. The study has been conducted combining a RADIANCE/DAYSIM lighting simulation with EnergyPlus for the thermal comfort and energy analysis. A set of metrics, able to express both the time constancy and the spatial uniformity of visual and thermal comfort conditions, has been evaluated together with the energy demand for heating, cooling, and lighting. The results show how a global approach allows obtaining a more comprehensive building performance evaluation and, consequently, identifying design solutions capable of enhancing both energy efficiency and occupant comfort
Comfort metrics for an integrated evaluation of buildings performance
No full textThe capability of expressing all the different aspects of the building's performance, besides and beyond the mere energy behavior is becoming more and more important, because of the increased expectations related to either new construction or the renovation of existing buildings. Even though building energy performance is one of the main aims of an appropriate design process or of a suitable management strategy during the operation phase, it can be strongly undermined by the underestimation of the role of the indoor environmental quality. Poor thermal or visual comfort not only affects occupant satisfaction, well-being and productivity, but also induces actions and operations that ultimately compromise the energy efficiency targets. In order to support the design approach, including, since the very beginning, the comfort conditions among the design requisites, a set of metrics is proposed in this work, considering either time constancy or spatial uniformity of a single comfort aspect -or of different aspects at the same time. These metrics have been applied to a simulated reference environment, in order to test their ability to represent the performance of the envelope components when comparing building configurations characterized by high solar and daylighting gains and different window and shading configurations
On The Representation Of The Thermal And Visual Behavior Of A Roller Shade Material: Comparison Between Different Simulation Models
Full text linkShading systems, if efficiently operated, can improve the internal environmental quality, namely both thermal and visual comfort, and reduce the energy consumption due to cooling needs. Roller shades represent one of the most commonly used types of shading systems, in particular in the tertiary sector. Not only they can be easily installed and maintained, but also they often represent the only design choice when existing buildings are considered. Although roller shades are characterized by a beam-beam and by a beam-diffuse transmittance, both changing according to the incidence angle, as the transmitted solar radiation decreases with the increase of it, they are typically modelled assuming equal reflectance and emissivity for both sides and perfect diffuser behavior, with transmittance and reflectance independent from the solar radiation incidence angle. Neglecting the daily variability of these properties can lead to underestimate their impact on the occupants comfort conditions. In this paper, different models for representing the roller shades behavior, embedded in two widely diffuse simulation codes have been compared with a set of measured data, recorded at the Bowen laboratories of the Purdue University (Indiana USA), combining thermal (Energy Plus) and lighting simulation (Energy Plus or DIVA for Rhino). The thermal properties of the building materials and the internal gains have been calibrated for the thermal simulation, in order to evaluate better the models capability of predicting the roller shades behavior. Then, starting from the simplest daylighting model, which assumes the roller shades as perfect diffusers, more complex characterizations have been considered and validated through the comparison with the measured data.
Long-term and spatial evaluation of the integrated performance of a window-shade system in an open space office located in Rome
No full textThe building façades, as a boundary between external and internal environments, play a central role in energy reduction and suitable comfort conditions maintenance. Their evaluation requires an integrated assessment approach, focused on occupants’ thermal and visual comfort, in time and space, as well as on maximizing daylight and achieving energy saving goals. In this paper, dynamic simulation is used to evaluate the integrated performance of different fenestration systems in an open space office located in Rome. The illuminating analysis has been performed using DIVA, and the results, processed by means of a Matlab code, have been used as an input for Energy Plus thermal and energy analysis. Then, the Energy Plus outputs have been post processed to calculate the solar radiation influence on occupants thermal comfort. Some new metrics have been introduced in such a way that it is possible to assess the
comfort performance with comprehensive indicators
Dynamic Commercial Façades versus Traditional Construction : Energy Performance and Comparative Analysis
No full textDriven by architectural trends and the need to maximize daylight, commercial building façades have become more transparent. High-performance façades include spectrally selective glazing systems, dynamic elements and insulated spandrel sections. Nevertheless, it is generally accepted that, compared to standard, traditional opaque construction, modern transparent envelopes result in increased overall energy use in these buildings. In this paper, the building façade is treated as a part of the building perimeter zone, which also includes electric lighting controls, shading attachments, HVAC components, and indoor environmental controls. Consequently, the objective is to balance the need for daylighting and view versus the need for controlling of solar gains and maintaining human comfort, while reducing energy demand for air conditioning and lighting. Key parameters in solving this problem are (1) technological advancements in glazing products, (2) utilization of dynamic building envelope components, and (3) lighting and HVAC controls. In order to demonstrate the potential of high-performance façades, a typical office building with large perimeter zones is used as an example. The basic model consists of standard brick exterior walls with 20% punched windows. Then, a comparative analysis is performed for a more transparent envelope with dynamic systems including shading and electric lighting controls, for the climates of Chicago and Rome. An integrated thermal-lighting model with flexible dynamic system controls, verified with commercial software, is expanded to simulate more complex façade controls for reducing glare problems while maximizing useful daylight. The results show the advantages of transparent façades with active systems, compared to traditional building envelopes. The more transparent building results in lower operational costs and source energy use, although total site energy use can be higher for heating-dominated climates
Comfort and energy performance analysis of different glazing systems coupled with three shading control strategies
No full textShading control strategies are often required to optimize the balance between solar gains, daylight availability, glare protection, and view to the outside. Automated shading operation, when properly designed, may avoid performance losses due to manual operation while maintaining indoor environmental comfort. In this work, the integrated performance of different glazing systems coupled with three control approaches for roller shades is presented for a typical office space. The first control is a standard open–closed operation based on a workplane illuminance range, while the other two are able to set intermediate shade positions according to the solar position to maximize daylighting. The third control addresses excessive daylight on the workplane by imposing a workplane illuminance threshold to reduce the risk of daylight discomfort glare. Daysim, based on Radiance and the daylight coefficient method, was used to calculate the annual illuminance profile over the workplane, and Evalglare was used to calculate glare indexes. EnergyPlus was used for thermal comfort and energy analysis. The results were processed through aMATLAB code for transferring required information from one tool to another. Moreover, to assess the global performance of the shading controls and fenestration configurations studied, visual and thermal comfort were evaluated through a set of metrics able to express both the availability (the fraction of time with acceptable comfort conditions at specific positions) and the spatial usability (the fraction of space simultaneously within comfort range at specific moments). The energy performance was also quantified in terms of primary energy demand for heating, cooling, and lighting. The results showed that it is possible to balance daylighting, thermal and visual comfort, and energy use. This can be achieved by simultaneously selecting shading controls that allow adequate daylight without causing glare, and glazing properties with good thermal performance that allow adequate daylight (high visible transmittance) but limit solar gains (lower solar transmittance or solar heat gain coefficient [SHGC]) for moderate and cooling-dominated climates
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
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
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