Journal of Daylighting 4 (2017) 37–47 2383-8701/© 2017 The Author(s). Published by solarlits.com. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). RESEARCH ARTICLE doi:10.15627/jd.2017.6 ISSN 2383-8701 Journal of Daylighting Journal homepage: http://www.solarlits.com/jd Effect of Window Glazing on Colour Quality of Transmitted Daylight Rajendra Dangol, ∗ Thijs Kruisselbrink, Alexander Rosemann Department of the Built Environment, Building Lighting Group, Eindhoven University of Technology, Eindhoven, The Netherlands Article info Article history: Received 16 August 2017 Revised 12 October 2017 Accepted 17 October 2017 Published online 9 November 2017 Keywords: Colour rendering Colour quality CIE CRI Window glazing Abstract In this study, the colour quality of the daylight transmitted through different window glazing types is evaluated. The analysis considered four different types of window glazing: laminated, monolithic, coated and applied film glazing ranging in luminous transmittance from around 0.97 to <0.1. The spectral transmittance data of different window glazing types are taken from the International Glazing Data Base (IGDB), which is maintained by Lawrence Berkeley National Laboratories (LBNL). The study showed that the CIE CRI does not always seem to be the suitable method to predict the colour quality of daylight in building for particular situations. However, in the context of this study, the prediction of colour rendering properties of window glazing by other metrics such as Colour Quality Scale (version 9), Memory CRI, R a,D65 (adjusted CRI metric with D65 as the reference illuminant) performed better. For most of the daylit situations inside the building, the chromaticity difference criterion was not met. Judging the colour quality of such situations requires different method. © 2017 The Author(s). Published by solarlits.com. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). 1. Introduction Window glazing technologies are developing and improving rapidly. This applies to coated, laminated, applied film and monolithic glazing systems. Advanced glazing systems have a great potential to save energy, costs from heating, air-conditioning and lighting, when correctly integrated in the building’s façades to exploit the utilization of daylight. It plays a vital role in maintaining the visual and thermal comfort, view to outside, privacy and indoor air quality [1,2]. Window glazing enables the variation of the luminous transmittance, solar factor and spectrum of daylight within buildings. It has many benefits over conventional shading solutions such as less or unperceivable visual obstruction, lower maintenance requirements, the absence of movable parts and operation-related noises. Many studies have reported that window glazing types are capable of reducing energy consumption for cooling and lighting [3,6], increasing visual comfort [7,8] and glare protection [9,10]. However, the colour quality of daylight transmitted through smart glass is of serious concern. For general lighting, the colour quality of a light source is a vital characteristic. To date, the colour quality of a light source does not have any rigorous definition. The word quality should be regarded as a general term. A dictionary defines the term quality as “the degree of excellence of something”. In the case of the colour quality, it means the degree of colour excellence. Colour cannot be measured directly; it is always based on a comparison [11] which then allows the formulation of a colorimetric system such as the one consisting of the components hue, chroma and lightness. Similarly, it is not possible to measure the colour quality of light sources without a reference or comparison. However, various components/aspects of colour quality such as colour fidelity (colour rendering), colour discrimination, colour harmony, colour preference, visual clarity, colour acceptability, and brightness [12] can be determined. Even though there are different aspects of colour quality, currently, the light source is judged with the help of Commission International de l’Eclairage (CIE) Colour Rendering Index (CRI). CIE CRI is the only internationally recognized metric to measure and specify the colour rendering properties of a light source [13]. It is widely accepted and has been used for over 40 years. However, many deficiencies are associated with the CIE CRI [14–16], including the use of relatively low saturation test samples and the use of outdated colorimetric tools. The same CIE CRI has been used to judge the colour quality of the luminous environment resulting from different smart glazing systems in various studies [17–19]. Ghosh and Norton [17] examined the colour rendering properties of daylight transmitted through a suspended particle device smart glass. They found that the CIE CRI values and correlated colour temperature (CCT) of daylight transmitted * Corresponding author. r.dangol@tue.nl (R. Dangol) t.w.kruisselbrink@tue.nl (T. Kruisselbrink) A.L.P.Rosemann@tue.nl (A. Rosemann)