This study evaluates the performance and robustness of 22 established and newly proposed glare prediction metrics. Experimental datasets of daylight-dominated workplaces in office-like test rooms were collected from studies by seven research groups in six different locations (Argentina, Denmark, Germany, Israel, Japan and the United States). The variability in experimental setups, locations and research teams allowed reliable evaluation of the performance and robustness of glare metrics for daylight-dominated workplaces. Independent statistical methods were applied to individual datasets and also to one combined dataset to evaluate the performance and robustness of the 22 glare metrics. As performance and robustness are not established in literature, we defined performance as: (1) the ability of the metric value to describe the glare scale (evaluated by Spearman rank correlation), and (2) the ability of the metric to distinguish between disturbing and non-disturbing situations (evaluated by diagnostic receiver operating characteristic curve analysis tests). Furthermore, we defined robustness as the ability of a metric to deliver meaningful results when applied to different datasets and to fail as few as possible statistical tests. Average Spearman rank correlation coefficients in the range of 0.55–0.60 as well as average prediction rates to distinguish between disturbing and non-disturbing glare of 70–75% for several of the metrics indicate their reliability. The results also show that metrics considering the saturation effect as a main input in their equation perform better and are more robust in daylight-dominated workplaces than purely contrast-based metrics or purely empirical metrics. In this study, the daylight glare probability (DGP) delivered the highest performance amongst the tested metrics and was also found to be the most robust. Future research should aim to optimise the terms of glare equations which combine contrast and saturation effects, such as DGP, PGSV or UGR_exp, to achieve metrics that also perform reliably in dimmer lighting conditions than the ones explored in this study.

Discomfort glare is a major challenge for the design of workplaces. The existing metrics for discomfort glare prediction share the limitation that they do not take gaze direction into account. To overcome this limitation, we developed a ‘gaze-driven’ method for discomfort glare assessment. We conducted a series of experiments under simulated office conditions and recorded the participants’ gaze using mobile eye tracking and the luminance distributions using high dynamic range imaging methods. The two methods were then integrated to derive ‘gaze-centred’ luminance measurements in the field of view. The existing ‘fixed-gaze’ and the newly developed ‘gaze-driven’ measurement methods are compared. Our results show that there is a significant difference between the two methods. In this paper, the procedure for integrating the recorded luminance images with the recorded gaze dynamics for obtaining gaze-centred luminance data is described. This gaze-centred luminance data will be compared to the subjective assessment of glare in Part 2 of this study.

Advancing energy efficient renovation solutions in residential buildings necessitate adopting high-insulation and airtightness to avoid heat loss through transmission and infiltration, which can result in overheating. Elevated indoor temperatures have been proved to have a highly negative effect on occupants’ health and well-being. Energy efficient solutions to the problem with overheating include limiting the solar heat gains through the glazed parts of the facade and effective ventilation. A typical Danish residential apartment building from 1850-1900 recently refurbished, was modelled with five different solar shading devices and three typical ventilation solutions. External solar shading could efficiently reduce overheating below the limits specified by the national building regulations in all tested cases. The marquisolette reduced the number of occupied hours with temperature above 27 °C by min. 85%, the external venetian blinds by min. 81%, and the drop arm awning by min. 74% compared to the situation without solar shading. The internal solar shading as venetian blinds and roller blind could reduce the overheating hours by 20-40%, which was efficient only in combination with mechanical ventilation in case of south and east building orientations.

Solar shading can be an effective way of avoiding overheating by reducing solar gains in buildings. However, solar shading systems can block or obscure the view-out with the consequence that occupants may refrain from using the shading system. As such, there is a need to quantify the effects of shading on occupants’ perception of the view. In this study, we developed a method to identify the photometric parameters and compositions that are effective in characterising the view-out in relation to different solar-control systems. We hypothesized that the photometric composition, e.g., contrast, in the visual environment as a result of using solar-control systems impacts the subjective assessment of the view. We conducted objective photometric measurements using calibrated luminance cameras and subjective responses from 64 participants in a semi-controlled work environment to test the hypotheses. The participants were randomly allocated to a combination of five view-outs and six solar shading systems in a work environment where they answered questions related to the indoor environment and view quality. The relation between view and solar-control systems and their impact on the subjective view assessment was tested using linear mixed-effects models. The models were developed using forward and backward selection based on AIC and likelihood ratio tests (LRT) to test the effects of adding or removing variables. The achromatic contrast calculated based on the measured luminance data both locally and globally was significantly associated with view assessment and satisfaction when using different shading types.