Optical model for prismatic glazing (1415-RP) (original) (raw)
Related papers
Modelling the optical and thermal properties of complex glazing: overview of recent developments
Solar Energy, 2001
The recently completed ALTSET project was part of the European Commission's Standards, Measurement and Testing programme. Its objective was the development of European standard test procedures for the determination of angular-dependent light and total solar energy transmittance for complex glazings and integrated shading elements. In parallel to the development of test procedures, models to predict the properties of a variety of complex glazings were developed and validated. We review the progress made during this collaborative programme. Models have been developed for a wide range of complex glazings, including those incorporating solar control films, transparent insulation and both fixed and variable blinds. The models are based on the concept that a complex glazing can be represented by a stack of layers, each layer representing one of the component elements of the glazing. If the optical and thermal properties of each layer are known, methods are available to calculate the corresponding properties of the stack. Used with some caution, the models are able to predict the luminous and total solar energy transmittance to an accuracy comparable to that obtainable experimentally. The models are suitable for integration into building energy simulation tools. One area requiring further investigation is an improved model for scattering components.
Accuracy of empirical angular variation model for solar absorptance of architectural glazing
Thin Solid Films, 2006
A new empirical way of predicting solar absorptance in windows has been proposed. Solar light is traditionally assumed to have nearnormal incidence. This is an approximation since light reaches the window from all angles between 0-and 90-. The approximation leads to an incorrect estimate of the solar absorptance, since the absorptance actually varies with angle of incidence. In this study, international standards and Fresnel calculations have been used to calculate the error in the total solar absorptance with this near normal approximation, with a clear pane approximation, as well as with our new angular variation model. The new model implies knowing to which of nine groups the window belongs and using a set of polynomial fits to the angular absorptance, one set for each window group (one polynomial fit for each window pane). It is shown that the error with the new model is considerably smaller than with the other two approximations, especially at high angles of incidence. D
Experimental characterization of glazing with glass prisms
Solar Energy, 2017
The principles of design for two types of prismatic elements have been studied. The theoretical approach has been used for design of the glass prisms to optimize their function for given application and geographic location. The two manufactured prismatic glass elements have been applied in triple glazed window samples with a low emissivity coating and experimentally tested to determine the realistic angular selective optical properties. A specific test stand for glass prism transmittance measurement has been developed and applied. The results have been compared with conventional triple glazing with clear glass panes and triple glazing with solar control pane applied, both alternatives with the identical low emissivity coating. Significant advantages of transmittance selectivity (low transmittance for high solar altitude – summer condition, high transmittance for low solar altitude – winter condition) have been proved especially for triple glazing with reverse symmetrical prism. The ...
strongly influence the energy performances of buildings, especially in the new hugely glazed constructions. Many advanced glazings were produced to improve the thermal and optical properties of windows, but for these products the angular dependence of optical and solar parameters are from the traditional glass decay curves. Computer tools often do not solve the problem of the inputting of effective solar and luminous parameters of transparent surfaces, since they consider only the traditional glazings behavior. The energy loads of an office building are calculated, by means of ad-hoc models and simulations with TRNSYS, to evaluate the errors that energy building simulation programs get into, without considering the effective properties of advanced glazing systems.
Hybrid equivalent model algorithm for the prediction of glazing angular properties
Solar Energy Materials and Solar Cells, 2002
Daylighting and energy consumption evaluation for actual rooms requires knowledge of the luminous and energetic parameters of the fenestration, both at normal and off normal incidence. In the case of coated glazings, the off normal parameters can be achieved only with very complex measurements. The Hybrid Equivalent Model Algorithm allows the prediction of the fenestration characteristics solely on the basis of the transmittance and reflectance spectra, measured at normal incidence, without need of any information about the coating composition. In this paper, the algorithm effectiveness is tested on single, double and triplepane glazings by applying it to a set of synthetic coated glasses, inspired by real specimens; the variety of the considered coatings makes this set quite representative of the industrial production. The results are very encouraging: for 19 samples, on the 22 considered here, the mean deviation of the g-factor from the true values is less than 1%; for the remaining 3 it is not larger than 3.7%, and probably it could be reduced by further refining of the hybrid model because these 3 samples belong to the same product class. r (P. Polato) 0927-0248/02/$ -see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 -0 2 4 8 ( 0 1 ) 0 0 0 9 1 -5
Specification of Glazings for Façades Based on Spectrophotometric Characterization of Transmittance
Sustainability
The correct specification of glazings for façades can reduce the energy consumption in buildings. The heat exchange occurs through transparent surfaces and radiation reaches the building as light and heat. Therefore, glazings significantly contribute to the heat transfer between outdoor and indoor spaces and act directly on daylighting and thermal comfort. This paper reports on the spectrophotometric characterization of glazings transmittance for the study of components of a modular façade system and its suitability for the climate of Portugal (temperate climate). The study focused on results of spectrophotometric measurements of optical properties, specifically the transmittance of some types of glazings (solar control, self-cleaning, low-e, float, and extra-clear) and two types of double glazings. The results show the percentage of transmission to ultraviolet, visible, and near-infrared regions and its importance, which enabled the analysis of the glazing efficiency regarding dayl...