Roberto Germán Rodriguez

Effects of perceived indoor temperature on daylight glare perception

This research investigates the effects of perceived indoor temperature on glare sensation. A laboratory experiment was carried out where volunteers (n = 19) performed an office-like computer task. Three scenarios with sunspots over the desk were evaluated: a cold scenario, a comfort scenario and a hot scenario. All had the same vertical illuminance at the eye and luminance ratios. Discomfort glare was measured with the predictive daylight glare probability (DGP) model; actual perception of glare was assessed with glare sensation vote (GSV) scale; while thermal comfort was evaluated with thermal sensation vote (TSV) scale. In order to know how much the perceived temperature contributes to the model, an ordinal regression was performed. The result showed a Nagelkerke pseudo-R2 = 0.52, p = 0.001, indicating that the perceived temperature affected glare predictions. This is an improvement in the understanding of daylight glare, which will allow researchers and practitioners to make informed decisions about sustainable design and occupant comfort. In conclusion, a more comprehensive glare model should include perceived temperature as a variable of the current glare model. Also, the results suggest that DGP should be used only when the person is in thermal comfort.

Glare and cognitive performance in screen work in the presence of sunlight

Research concerning the effects of glare on distraction is scarce. We designed a 2 × 2 repeated measures experiment (n = 32) in order to examine the influence of a large area glare source and glare sensitivity on reported discomfort glare and cognitive performance. Daylight glare probability was the within-subjects variable and glare sensitivity was the between-subjects variable. We found a statistically significant difference in glare sensation votes between scenarios, without statistically significant differences in glare ratings due to glare sensitivity. We found some statistically significant effects on our participants’ reaction times. Also, we calculated their effect sizes, which had practical relevance. Our results encourage further research in an issue that has been suggested since the early stages of glare research but has never been systematically and consistently addressed.

Glare indicators: an analysis of ocular behaviour in an office equipped with venetian blinds

This article studies the ocular behaviour of office workers in the presence of glare. Additionally, the study seeks to obtain a new indicator for glare prediction that compensates the inaccuracies of glare predicted by the existing models of glare sensation vote (GSV), daylight glare probability (DGP) and daylight glare index. A laboratory experiment was carried out (n = 18) simulating an office space. The volunteers participated in four office tasks (reading from a screen and from a paper, writing and socializing). Two scenarios were evaluated: one with sunspots on the faces of the subjects and the other with sunspots on the working area. By means of a visible spectrum eye tracker these ocular parameters were registered: direction of gaze, the degree of opening of eye and pupil size. These ocular parameters were correlated with vertical illuminance at the eye. The results show that the degree of reduction of opening of the eye was the best predictor of visual discomfort with statistically significant differences between scenarios (p = –0.728, s = 0.001). The other important predictor was the pupil size. The degree of opening of eye and pupil size was correlated with glare indices. The degree of eye opening has a good correlation with GSV and DGP and it could be a future index of visual comfort under situations of the risk of glare.

Developing a modelling factor index for transition spaces: a case study approach

Transitional spaces (TS) are characterized by possession of high gradients of luminances between inside and out, which places a great demand on the users’ visual systems function. A satisfactory descriptive indicator of this kind of situation could be a ‘modelling factor’ (MF), defined from cylindrical illuminance and horizontal illuminance measures. It would provide information on the depth and dimensionality of objects present in the scene, also taking into account a regions overabundance of daylight. A public building was selected as a case study, and solar light behaviour, including its interaction with the space, was monitored. Measurements were taken during an entire year at the start of each season (2008) under clear skies, at the beginning and at the end of each working day. Another measurement was taken in winter (2009) under overcast skies at 13:00, so as to obtain a comparative parameter. It was found that unfavourable conditions were produced in all seasons for about 2 hours, except at 09:15 in winter. All the data collected in the control situation were within the optimum modelling range, with values ranging between 0.3 and 0.4. The MF allows the integration of most relevant factors intervening in TS and emerges as a good descriptor for TS.

Iluminación en unidades de cuidados intensivos neonatales: actualización y recomendaciones

Achieving adequate lighting in neonatal intensive care units is a major challenge: in addition to the usual considerations of visual performance, cost, energy and aesthetics, there appear different biological needs of patients, health care providers and family members. Communicational aspects of light, its role as a facilitator of the visual function of doctors and nurses, and its effects on the newborn infant physiology and development were addressed in order to review the effects of light (natural and artificial) within neonatal care with a focus on development. The role of light in regulating the newborn infant circadian cycle in particular and the therapeutic use of light in general were also reviewed. For each aspect, practical recommendations were specified for a proper well-lit environment in neonatal intensive care units.

Effects of a Large Area Glare Source in Cognitive Efficiency and Effectiveness in Visual Display Terminal Work

Abstract Glare is a common visual stressor of office work and in todays offices the prevalence of information and communication technologies adds additional mental demands. The aim of this study was to explore the role of light as a cognitive stressor in visual display terminal (VDT) work. We used a large area light source in a 2 × 2 × 2 full factorial experimental design. We assessed cognitive efficiency using the RTLX method and cognitive effectiveness using the RST method in different lighting scenarios. The main effects analysis showed lower working memory capacity for high luminance and large source, with statistically significant lower cognitive performance in prosaccade conditions. No statistically significant relationship was found between cognitive efficiency and the experimental factors.AbstractGlare is a common visual stressor of office work and in todays offices the prevalence of information and communication technologies adds additional mental demands. The aim of this study was to explore the role of light as a cognitive stressor in visual display terminal (VDT) work. We used a large area light source in a 2 × 2 × 2 full factorial experimental design. We assessed cognitive efficiency using the RTLX method and cognitive effectiveness using the RST method in different lighting scenarios. The main effects analysis showed lower working memory capacity for high luminance and large source, with statistically significant lower cognitive performance in prosaccade conditions. No statistically significant relationship was found between cognitive efficiency and the experimental factors.

A dynamic performance analysis of passive sunlight control strategies in a neonatal intensive care unit

Neonatal intensive care units are a special lighting design challenge. Although natural light is highly desirable, it should be carefully planned to maximise benefits and minimise the problems associated with uncontrolled sunlight. This paper discusses the performance of different passive sunlight control strategies in a neonatal intensive care unit at the Dr. Humberto Notti Childrens Hospital in Mendoza, Argentina, analysing their annual daylight behaviour through dynamic daylight simulations. The aim of this work is to optimise the use of daylight in neonatal intensive care units, considering the special lighting conditions required. Results show that, in this case study, the adequate implementation of solar control systems and the appropriate layout of the space for different uses according to surrounding building design and the characteristics of the local luminous climate can increase the useful daylight illuminance by up to 13%, while avoiding the incidence of direct sunlight at all times.