A Non-Ventilated Solar Façade Concept Based on Selective and Transparent Insulation Material Integration: An Experimental Study

Abstract

A new solar façade concept based on transparent insulation and a selective absorber is proposed, tested and compared with conventional insulation and a non-selective type of absorber, respectively. The presented study focuses on an experimental non-ventilated solar type of façade exposed to solar radiation both in the laboratory and in outdoor tests. Due to the high solar absorbance level of the façade, high-and low-emissivity contributions were primarily analysed. All of the implemented materials were contrasted from the thermal and optical point of view. An analysis was made of both thermodynamic and steady state procedures affecting the proposed solar façade concept. Experimental full scale tests on real building components were additionally involved during summer monitoring. An indicator of the temperature response generated by solar radiation exposure demonstrates the outdoor performance of the façade is closely related to overheating phenomena. From the thermal point of view, the proposed transparent insulation and selective absorber concept corresponds to the performance of conventional thermal insulation of identical material thickness; however, the non-selective prototype only provides 50% thermal performance. The results of the solar-based experiments show that with a small-scale experimental prototype, approximately no significant difference is measured when compared with a non-selective absorber type. The only difference was achieved at the maximum of 2.5 K, when the lower temperature was obtained in the solar selective concept. At the full-scale outdoor mode, the results indicate a maximum of 3.0 K difference, however the lower temperature achieves a non-selective approach. This solar façade can actively contribute to the thermal performance of building components during periods of heating.

Preparation and Characterization of a Selective Polymer-Based Solar Absorber for Building Integration

“…As mentioned in previous sub-sections, samples of the developed absorber were spectrally analyzed to evaluate their optical performance. Samples of six other absorbers were also analyzed for comparison purposes: three samples of black painted absorbers (S1-S3) and three samples of commercially available selective absorbers (R1-R3) that were characterized in the authors' previous work [20]. An overview of the tested samples is presented in Table 1.…”

“…Such temperatures are appropriate for solar thermal systems [17][18][19]. However, it has been also shown [20] that a suitable design of an absorber system integrated in a building facade can reach a maximum temperature of approx. 80 • C. This enables the use of less demanding (and expensive) materials, such as polymers, for the production of absorbers, resulting in notable economic and environmental benefits.…”

“…The results also show that thermal emissivity of the developed P1 absorber is approximately 25% worse than that of commercial selective absorbers R1-R3 due to the presence of the polyethylene absorbent layer. Thermal emissivity is a key parameter for the determination of the heat transfer coefficient and the heat loss of any solar thermal system (e.g., solar facades with selective absorbers as described in [12,20,33,49]). When evaluating efficiency of the absorber, both parameters should be included in the selectivity parameter.…”

Life Cycle Assessment of Solar Façade Concepts Based on Transparent Insulation Materials

“…Dynamic modelling was selected as literature such as [36] suggests that it should provide the most accurate data for LCA. This type of modelling considers the thermal and spectral parameters of the evaluated materials that were obtained in the course of research for previous works ( [34,37]) as well as varying exterior conditions. A summary of the material parameters is in Table 4.…”

Energy Efficiency of a Solar Wall with Transparent Insulation in Polish Climatic Conditions

“…At this point, it should be mentioned that the appropriate orientations of the walls equipped with transparent insulation may be from east through south to west; however, a southern orientation is preferred. The reduction of excessive solar gains can also be achieved by using appropriate selective absorbers [15][16][17] and thermotropic layers integrated with transparent insulation, which reversibly reduce the total solar energy transmittance, becoming opaque after heating [10]. Works [3,[18][19][20] provide an overview of insulation systems based on transparent materials, as well as the materials which transparent insulations are made of.…”