Daylighting is desirable in classrooms but can pose a challenge to classroom illumination when there is a risk of discomfort from glare from windows and sunlight. There are several metrics in use for the evaluation of discomfort from glare from daylight, but none has yet been validated based on the field-of-view conditions of classrooms. A previous study found that Daylight Glare Probability (DGP) produced a relatively better predictive power of the reported discomfort from glare in a classroom compared to other metrics. However, the metric tended to correlate weakly with the reported glare in positions away from the window light source in a classroom. This prompted the current investigation
on the possibility of improving the DGP equation. The modified equation produced a significantly better fit to the subjective glare evaluations from a dataset comprising 184 evaluations from 49 participants collected in a classroom. The results suggest that DGP can be improved to predict the reported discomfort from glare for the conditions of board-based work in a classroom, particularly when a logarithmic form of the adaptation term is integrated in the equation. ... Read more

Provision of daylight without the risk of discomfort glare is one of the aspects that determine the quality of the classroom environment. Although discomfort glare from daylight is under investigation for a long time, a knowledge gap concerning the applicability of the existing metrics to the spatial conditions of the classroom is identified in this work. An investigation on the applicability of existing metrics to the prediction of discomfort glare in classrooms has been carried out based on two experimental studies. The analysis shows that the existing metrics have poor predictive ability particularly in the sitting positions away from the window light source. A study is then carried out to investigate how can more appropriate predictive models of discomfort glare be developed, based on three different methods. A modification of the Daylight Glare Probability (DGP) equation produced a significantly better discomfort glare model than any of the metrics that have been studied in this work. Following this finding, a new metric, DGPlog(Ev)new, is proposed. The produced metric suggests that discomfort glare in the classroom is better identified based on a range of equations for different sitting positions or that new variables that account for sitting position need to be included in a predictive model of discomfort glare for these spaces. A set of architectural design guidelines towards a discomfort glare free classroom is then proposed, based on the newly produced model and on the collected data. ... Read more

This paper presents selected results from the first stage of DAYKE (Daylight Knowledge in Europe), a 3-phase project that investigates the knowledge on daylighting in buildings among architecture students and practitioners across Europe. Subjective judgements from 561 students from 8 architecture universities in the EU, collected through two surveys in 2018. The key findings are: (i) the spatial distribution of comfort and mood in the classrooms varied depending on sky conditions and distance from windows; (ii) the average daylight factor DF_m showed a good agreement with subjective judgements on the amount of daylight in a space; (iii) experts and non-experts provided similar judgements on the perception of a daylit environment; (iv) a general lack of knowledge about daylighting metrics, regulations, assessment tools and software was highlighted. Furthermore a difficulty in implementing daylighting into the design practice is also identified. ... Read more

The calculation of field-of-view luminance based metrics for visual discomfort from glare evaluation in real scenes via HDR (High Dynamic Range) luminance capture does generally require the use of wide view fisheye lenses. This paper presents an easy to implement and low-cost method to estimate a fisheye lens’ total field-of view and projection method, which is required for accurate glare evaluations. ... Read more

The objective of the present study was to find how well a group of selected luminance-based metrics predict reported visual discomfort from daylight glare in spatial conditions that differ from the conditions where metrics tend to developed and validated for. An empirical study involving the assessment of visual discomfort from glare by n=50 subjects (n=185 cases) in a daylit-only classroom space was carried out to investigate this problem. It was found that the glare indexes were the most robust metrics predicting reported glare. However, as all metrics failed most of the statistical tests in the near-wall zone of the classroom, it can be said that none of the metrics was able to predict with enough accuracy the glare reported across the space. Indeed, the metrics show a very poor performance in the sitting positions away from the window, an aspect that requires further investigation. ... Read more

Two independent surveys were conducted in 2017 and in 2018 among architecture students across Europe to investigate their knowledge on daylighting and the impact of that knowledge on the visual perception of daylit spaces. A total of 600 responders were involved. This paper presents findings from the second survey, which was distributed in six European countries. Based on the findings from the first survey, a new goal was set for the second survey: to examine how daylighting knowledge may influence the visual perception of it and how the perception of a daylit space by a student population and by experts compare to each other. Three main findings were observed: i) the perceived comfort shows a better agreement with mood than with sky condition; ii) the judgments expressed by the experts and by non-experts are consistent with each other, confirming an outcome of the earlier study and iii) there is a lack of knowledge about daylighting metrics and regulations as well as a difficulty in implementing daylighting into the design process. These outcomes highlight the relevance of reconsidering the way daylighting education is delivered in current architectural programmes. ... Read more

DAYKE (Daylighting Knowledge in Europe) is a project to investigate the daylighting knowledge and skills of Architecture students and practitioners from different countries within the European Union. This paper introduces the first stage of the research and provides results from a direct survey taken by 161 students from seven schools of Architecture: two in Italy, one in The Netherlands, two in Poland and two in Spain. The results indicate significant national differences in preference and perception of daylit spaces. They also show a lack of knowledge about daylighting metrics and regulations among the respondents. Although the research is undergoing, the preliminary data analysis indicates that there is a need for enhancing the daylight knowledge among future architects. ... Read more

This paper reports on a pilot experiment to test the applicability of a group of metrics to the prediction of visual discomfort in a daylit classroom environment. In particular, if the position in relation to the window has an impact in the way visual discomfort from glare is reported, and if the metrics predict that discomfort accordingly. Subjects (N=21) performed a typical classroom task in four different positions in a classroom and were asked to rate visual discomfort from glare via a questionnaire at the same time that luminance measurements were collected. Daylight Glare Probability (DGP) provided the best agreement with the reported glare overall, but the ratio between the maximum luminance to mean task luminance of 30:1 in the 172º field-of-view depicted most of the reported discomfort votes. The results show that glare is reported for situations of low vertical eye illuminance, as also found in previous studies. ... Read more