Solar protection devices significantly impact buildings' energy efficiency, and a particular technology's shading potential is directly proportional to its optical qualities and performance. This is an important issue in contemporary architecture due to the extensive use of transparent materials.
The primary function of manually controlled shade systems is glare control, with location determined by the user's preference. The user cannot alter the configuration and choose to turn on the interior illumination as needed. Therefore, static shading systems can contribute significantly to energy savings, provided they are precisely built and parameterized in accordance with the climatic site's features.
Cost-effectiveness and easy implementation associated with fixed shading devices are appealing, but it has limitations in dealing with various weather conditions. Detailed analysis is carried out for shading devices in the early stages of designing the building envelope and building itself.
3D Shading Systems
3D systems provide solutions for second skins in buildings since easy paneling and shading of architecture glazed façades is possible due to their geometry.
Advanced surface treatments, enhanced conventional materials and new evolved materials from the industry are used to build fixed screens parallel to complex-shaped second skins, adjustable slats, and overhands.
The texture, openness, varying thickness and complex geometries are associated with 3D systems. These systems' optical and solar properties are determined by considering key parameters such as edge effect, internal ray reflection and system curvature.
This study optically characterizes the 3D systems by their solar shielding potential for façade applications. Implementing a reliable dataset and conducting analysis at the material level is imperative for laying the conditions for successive technology assessments of architectural design.
How the Study was Carried Out
The study is conducted in various phases. The first step is identifying, selecting and providing the description of functional 3D materials, such as geometry and material characteristics.
Optical properties of the sample are determined as a function of solar radiation angle and wavelength. Finally, samples' angular transmittance properties are evaluated and compared with the standard fixed shading system taken as a reference.
For experimentation, the materials are categorized into five distinctive categories, including 3D textile, plastic grid, metallic plissé, 3D expanded metal mesh, and metal grid and metal mesh. Fourteen samples were prepared from these categories, and experiments were conducted.
Measuring the optical properties of a 3D system is not possible using conventional spectrophotometers. Therefore, a spectrophotometer with a large‐diameter Spectralon coated integrating sphere (75 cm) was used to measure angular spectral transmittance.
Results of the Analysis
The openness factor is the primary parameter to determine the optical characteristics at normal incidence. Since 3D materials do not demonstrate spectrum selectivity, optical properties have the same value in the visible and solar range.
The solar transmittance of the plissé metal grid is 20%, metal meshes 70%, and 40% to 53% for the remaining samples.
Similarly, solar reflectance of plastic grids with large spaces is 1% to 2%, and perforated metal sheets have 39% to 44%. With transmittance decay of 60 degrees, plastic and plissè grids show relevant angular selectivity in the 58% to 72% range compared to the normal incidence value.
The results show that some tested samples have an intriguing potential for solar protection. However, due to their manufacturing flexibility, complexity and the large number of factors affecting shading performance, early-stage design of the 3D structures in a performance-based technique is recommended to maximize energy performance and architectural integration.
This study fills the gap in reliable optical solar properties of advanced 3D skins for solar protection. The data set presented in this study is very useful for several purposes, including analyzing energy performance and solar protection at an early stage, input data to take in these products in façade and building energy performance tools, and benchmark data for numerical model validation of the products.
This study analyzes the potential of 3D skins to provide efficient protection from solar. Several other aspects of this technology are fundamental. However, these have not been discussed in this research and are left for future studies in which the data and findings from this study will be very useful. For example, this study will contribute to research on the soiling and aging problem in metallic skins, diffraction-related visual quality problems and obstruction of the exterior environment, and the impact on daylighting.
Andrea Giovanni Mainini, Alberto Speroni, Tiziana Poli, and Michele Zinzi (2022) On the Optical Characterization of Architectural Three-Dimensional Skins and Their Solar Control Potential. Buildings. https://www.mdpi.com/2075-5309/12/8/1103
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