1,720,970 research outputs found
On the Optical Characterization of Architectural Three-Dimensional Skins and Their Solar Control Potential
Full text linkThe use of second building skins is becoming a trademark in modern architecture, opening for innovative solutions, such as three-dimensional (3D) systems. This paper explores the potential of these systems to provide adequate solar protection to glazed façades by means of an advanced optical characterization. Spectral transmittance and reflectance of fourteen samples, belonging to several technological families, are measured with a built-in spectrophotometer, suitable to accurately characterize complex semi-transparent systems. Solar and lighting properties are then calculated. The normal optical properties strongly depend on the openness factor, thus the geometry primarily affects the performance. A total of 11 samples exhibit normal solar transmittance in the 40–53% range; the value decreases to 20% for the plissé metal grid and increases to 70% on average for metal meshes. The angular transmittance depends on the system texture geometry and its self-shading capabilities. It was found that such systems underperform as static conventional shading systems; however, one of the metal meshes, the plissé grid and the plastic grid exhibit relevant angular selectivity, with transmittance decay at 60° in the 58–72% range compared to the normal incidence value. The results show that some of the selected 3D systems provide adequate solar protection. The developed dataset can be used for early-stage design analyses, as well as for energy performance model input and validation
THE EFFECT OF CANOPY SHADING ON PERCEIVED THERMAL STRESS IN PEDESTRIAN AREA OF EXPO 2015
No full textUrban areas are characterized by a plurality of microclimates given by the diversity of morphologies, optical and radiative properties, solar access and air circulation in different street canyons. For these reasons, beyond strategies at urban scale, mitigation needs to be addressed at district or even at urban canyon scale, just like the design of buildings. Among different options, canopy shading has been proposed in several urban contexts, and to assess the impact of this mitigation technique on air temperature and outdoor thermal comfort conditions we performed numerical simulations for a north-south oriented urban canyon with high solar access (height to width ratio equal to 0.18) in the climate context of Milano (Italy)
Optical Properties evaluation of alternative 3D materials for shading device systems.
No full textShading device systems are mainly constituted by bidimensional adjustable elements (louvres) or textile surfaces (roller blinds). A secondary external building skin realized by three-dimensional materials and structures are generally proposed as an alternative. Their effectiveness in reducing solar gains and improving indoor luminous comfort depends primarily on their geometry. In the first part of this paper we present some measurements of the angular solar and visible transmittance properties of an expanded metal mesh sample. In the second part of the paper, we assess a qualitative behavior of the product comparing its angular shading profile with the solar incidence angle distribution on a vertical plane, depending on latitude and orientation. A workflow to reconstruct a physically based digital model of the sample using different geometry reconstruction technologies, considering both three-dimensional modeling, 3D scanning and image reconstruction
Performance over time of green roofs
No full textIn the last decades progressively growing efforts were spent to identify strategies and to develop tools and techniques helpful to design sustainable, resilient, and low energy built environments. Green roofs have been proved as an effective passive technique to both mitigate the effect of solar radiation in summer and reducing thermal losses in winter, but their performance may vary over time, depending on the environmental conditions. Herein, an overview on performance assessment of green roofs is presented, after experimental activity and numerical modelling
On the impact of hollow silica powder on the performance aerogel glazing systems in buildings: Results from laboratory and simulation analyses
Full text linkAerogel-based glazing systems are an effective solution to reduce space heating energy use in buildings, even if overheating risks in temperate climates exist due to the high solar transparency of the systems. This study analyzes the potential of an innovative solution, based on a mixture of granular aerogel and hollow silica powder, in small concentrations, to increase the reflectance of the aerogel layer and reduce solar transmission. A set of glazing samples, different in aerogel layer and powder concentration, were produced and test in laboratory to determine the relevant solar and thermal properties. It was found that at 7.5 % powder concentration the solar and light transmittance were reduced up 0.48 and 0.45 in a 0–1 scale, respectively. Analogously, the solar and light reflectance increased up 0.49 and 0.46, respectively. The thermal resistance of the system increased up to 0.18 m2K/W, peaking at 1.88 m2K/W for the 34 mm aerogel layer sample. The thermo-physical properties were used as input to simulate an office building in different climatic conditions; it was found that the proposed technology ensured total energy savings for 4 % powder concentration and higher; cooling energy savings were up to 21 % and total energy savings up to 21 %
Daylighting performance of three-dimensional textiles
Full text linkThe pattern and permeability characteristics that compose three-dimensional (3D) textiles are important as a textile shading component to the architecture, engineering and construction (AEC) industry. Moreover, due to their complex geometry, 3D fabrics require a detailed modeling for correct evaluation of performance. This paper aims to present and investigate the optical properties of six 3D fabrics proposed as an alternative to traditional roller blind shading systems, which could guarantee high daylight availability and visual comfort. The light transmission distribution for the different samples has been characterized by carrying out angular visual transmittance measurements, using integrating sphere optical benches, and virtual modeling using Radiance's genBSDF tool. The Bidirectional Scattering Distribution Function (BSDF) calculated with Radiance shows a good fit with the optical angular measurements, which were used as a benchmark and to calibrate models. The performance of the 3D textiles, in terms of illuminance, daylight availability, and glare, was assessed considering two of the set of 3D textiles as alternative materials for a movable internal roller shade system in an open office. The innovative system was compared with a traditional single layer fabric roller blind under different shading control strategies, 3D fabrics demonstrate the potential of increasing Daylight Autonomy while providing better uniformity and better connection with the outdoors due to a higher openness factor. The shading effect created by the 3D geometry of the textile can increase the openness factor while restricting glare
On the impact of hollow silica powder on the performance of aerogel glazing systems in buildings: Results from laboratory and simulation analyses
No full textAerogel-based glazing systems are an effective solution to reduce space heating energy use in buildings, even if
overheating risks in temperate climates exist due to the high solar transparency of the systems. This study analyzes the potential of an innovative solution, based on a mixture of granular aerogel and hollow silica powder,
in small concentrations, to increase the reflectance of the aerogel layer and reduce solar transmission. A set of
glazing samples, different in aerogel layer and powder concentration, were produced and test in laboratory to
determine the relevant solar and thermal properties. It was found that at 7.5 % powder concentration the solar
and light transmittance were reduced up 0.48 and 0.45 in a 0–1 scale, respectively. Analogously, the solar and
light reflectance increased up 0.49 and 0.46, respectively. The thermal resistance of the system increased up to
0.18 m2
K/W, peaking at 1.88 m2
K/W for the 34 mm aerogel layer sample. The thermo-physical properties were
used as input to simulate an office building in different climatic conditions; it was found that the proposed
technology ensured total energy savings for 4 % powder concentration and higher; cooling energy savings were
up to 21 % and total energy savings up to 2
Customized shading solutions for complex building façades: the potential of an innovative cement-textile composite material through a performance-based generative design
No full textPurpose: The paper aims to investigate the comfort-related performances of an innovative solar shading solution based on a new composite patented material that consists of a cement-based matrix coupled with a stretchable three-dimensional textile. The paper’s aim is, through a performance-based generative design approach, to develop a high-performance static shading system able to guarantee adequate daylit spaces, a connection with the outdoors and a glare-free environment in the view of a holistic and occupant-centric daylight assessment. Design/methodology/approach: The paper describes the design and simulation process of a complex static shading system for digital manufacturing purposes. Initially, the optical material properties were characterized to calibrate radiance-based simulations. The developed models were then implemented in a multi-objective genetic optimization algorithm to improve the shading geometries, and their performance was assessed and compared with traditional external louvres and overhangs. Findings: The system developed demonstrates, for a reference office space located in Milan (Italy), the potential of increasing useful daylight illuminance by 35% with a reduced glare of up to 70%–80% while providing better uniformity and connection with the outdoors as a result of a topological optimization of the shape and position of the openings. Originality/value: The paper presents the innovative nature of a new composite material that, coupled with the proposed performance-based optimization process, enables the fabrication of optimized shading/cladding surfaces with complex geometries whose formability does not require ad hoc formworks, making the process fast and economic
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
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