Responsive glazing systems: Characterisation methods, summer performance and implications on thermal comfort

Abstract

Abstract:In recent years, there have been several experimental and numerical researches on transparent envelope components that integrate phase change materials (PCMs). To address some of the drawbacks of these systems, new prototypes were created and their summer performance was monitored under Cfa climatic conditions (Turin, Italy). The proposed glazing system comprises a triple glazing unit with a thermotropic layer placed on the outer side, acting as a switchable shading system capable of regulating the phase transition of the PCM. The PCM is tested in both the inner and the outer cavity of the glazing, alternately. In this paper, the summer performance of these responsive glazing systems is reported, complementing the assessment of their performance under winter conditions, which was previously presented in another paper (Bianco et al., 2017). Two additional systems were also tested in parallel for reference purposes: a triple glazing unit with a thermotropic layer only, and a reference triple glazing unit. Direct solar transmission was assessed, and the correlation between glazing temperature and solar transmission coefficient of the thermotropic layer, when coupled with the triple glazing unit, was derived. The solar transmission as a function of the external surface temperature of the PCM glazing units was also evaluated. The energy performance was assessed by means of a long-term evaluation in addition to daily analyses during cloudy and sunny days. The capability of the aforementioned technologies to improve indoor thermal comfort was investigated, with the effect of the transmitted solar radiation impinging on the occupants also taken into account. The results highlight that the integration of a thermotropic layer in a triple glazing unit allows the cooling load through the transparent component to be reduced by one third when compared to a traditional triple glazing unit. The overall energy performance was found to be primarily affected by the position of the PCM; not only during winter season, but especially in summer, the PCM completed the phase transition only when placed in the outermost cavity. The thermal comfort conditions were improved, when evaluated in terms of traditional PMV, regardless of the position of the PCM layer. However, when the influence of the direct solar radiation impinging on the occupants was taken into account, the solution with the PCM layer located in the inner cavity presented a better performance.

Phase Change Materials in Transparent Building Envelopes: A Strengths, Weakness, Opportunities and Threats (SWOT) Analysis

“…• the geographical distribution of the studies, which also provides an indication of the climatic conditions of the study; • the climatic/seasonal distribution of the studies: winter season (37%) [12][13][14][15][16][17][18][19][20][21][22], mid-season (10%) [14,15,20] and summer (50%) [13][14][15][16][17]20,[23][24][25][26][27][28][29][30][31] season periods; • the most investigated PCM typologies, that have been found to be paraffin wax (60%) [14][15][16]18,19,22,23,[25][26][27][28][29][30][31][32][33][34][35] and salt hydrates (20%) [12,13,…”

“…• in all the papers, the PCM had been macro-encapsulated in containers, that is, glass containers (70%) [12][13][14][15][20][21][22][23][24][25]27,[30][31][32][33][34][35][38][39][40][41], polycarbonate containers (20%) [16,17,19,28,36,42] and aluminium containers (10%) [18,26,29]; • the technologies had predominantly been characterised in outdoor test cells (57%) [14,15,17-22, 24-27,29,31,35] and through laboratory analysis (53%) [12,13,17,20,23,[32][33][34][35][36][37][38][39][40][41][42], while some other studies had been carried out by coupling a modelling activity with an experimental activity (37%) …”

“…Goia et al [25] and Bianco et al [22,31] studied the technology that integrates Phase Change Material in triple glazing units (TGU) through experimental and a numerical analysis [49] in order to assess the thermo-physical behaviour of the components, by varying the position of the PCM layer in the inner or outer cavity of a triple glazing, and they obtained a better buffer performance-U value and thermal inertia-compared to the DGU technology.…”

Smart natural lighting systems

“…Recent research studies investigate the use of Transparent Insulation Materials (TIMs) for covering the building openings, providing energy savings both for lighting and heating and/or cooling (Bianco et al, 2017;Vlachokostas and Madamopoulos, 2017). Aerogel is one of the materials the performance of which has been investigated widely (Reim et al, 2005;Buratti and Moretti, 2012;Cotana et al, 2014).…”

Optimización del comportamiento energético y lumínico en edificios singulares de vidrio a través de modelos a escala

“…Fuente: www.lacasadeldesierto.es. (Bianco, Cascone, Goia, Perino, & Serra, 2017) Figura 24. Casa de Cristal,situada en Bornholm (Dinamarca)…”