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Glare is a common local visual discomfort that is difficult to identify with conventional light sensors. This article presents an artificial intelligence algorithm that detects subjective local glare discomfort from the image analysis of the video footage of an office occupant’s face. The occupant’s face is directly used as a visual comfort sensor. Results show that it can recognize glare discomfort with around 90% accuracy. This algorithm can thus be at the basis of an efficient feedback control system to regulate shading devices in an office building.

This technical report summarizes the work on the research project "Reduction of overheating in multi-storey apartment buildings in connection with facade renovation". The project was carried out at the Section for Energy and Services, Department of Civil Engineering at the Technical University of Denmark in the period 1 January 2016 - 31 December 2018. The total budget for the project was DKK 1.98 million, where the Landowners' Investment Foundation (Grundejernes Investeringsfond) supported with DKK 990,000. The objective of the project was to evaluate the potential of different solar control solutions combined with typical ventilation strategies to reduce indoor temperature excess in renovated Danish apartment buildings from the period 1850-1970. The target group for the project was the construction industry, building owners and residents, the community in general and the international research world.The project dealt with a thorough examination of the overheating risk and the determination of possible solutions, based on dynamic computer simulations in IDA Indoor Climate and Energy (IDA ICE) software. An MS Excel based tool called “Result Browser” was prepared to give the user possibility to explore the project results from over 400 cases. This report describes the cases studied and the models used in details. The results regarding the effect of different windows type, solar shading solution and ventilation strategies on overheating and energy consumption based on over 700 simulations performed in IDA Indoor Climate and Energy (IDA ICE) software are discussed in the report. The research group hopes that this study will contribute to an increased attention regarding the use of solar shading and ventilation during energy renovation. The authors would like to thank all master and bachelor students from DTU BYG who have contributed to the project.

Denne afsluttende rapport opsummerer arbejdet på forskningsprojektet ”Reduktion af risiko for overtemperatur i etageboliger i forbindelse med facaderenovering”. Projektet blev gennemført ved Sektion for Energi og Installationer, Institut for Byggeri og Anlæg ved Danmarks Tekniske Universitet i perioden 1. januar 2016 - 31. december 2018. Det samlede budget for projektet var 1.98 mio. kr. Grundejernes Investeringsfond støttede projektet med 990.000 kr. Formålet med projektet var at evaluere potentialet for forskellige solafskærmninger kombineret med typiske ventilationsløsninger for at reducere overophedning efter energirenovering af danske etageboligbyggerier fra 1850-1970 under hensyntagen til dagslysets mængde og kvalitet.Rapporten opsummerer de vigtigste resultater fra projektet og er målrettet byggebranchen, bygningsejere samt beboere. Med rapporten medfølger ”Resultatbrowser” – en MS Excel baseret database med projektets resultater. “Resultatbrowseren” muliggør visualisering af projektets resultater, der demonstrerer, hvordan forskellige renoveringstiltag påvirker det termiske indeklima og energiforbrug. Forskningsgruppen håber, at denne rapport samt “Resultatbrowseren” bidrager til øget opmærksomhed vedrørende brug af solafskærmning og ventilation ved energirenovering. Forfatterne af denne rapport vil gerne takke alle studerende, der har arbejdet på projektet for deres bidrag.

This dissertation proposes a novel gaze-driven approach for dynamic discomfort glare assessments as a first step towards understanding human responsive comfort with respect to daylight. The objective was to observe the natural gaze behaviour in relation to glare for office spaces with the conditions implicitly constrained by real world luminous conditions. In the existing visual comfort models human behaviour is not sufficiently considered. These models employ only subjective assessments, which lack an objective understanding of the factors affecting the perceptual mechanism of light-induced visual discomfort. They so far have not integrated the inter-dependencies of visual discomfort perception and human gaze responses and have been limited to a fixed-gaze assumption directed towards the office task area. In this dissertation, a gaze-driven approach is developed and adopted in the discomfort glare assessments. The assessments were done in a series of experiments in simulated office setting under different lighting conditions where participants’ gaze responses with means of mobile eye-tracking as well as their subjective assessments were recorded while monitoring photometric quantities relevant to visual comfort using high dynamic range luminance imaging. Integration of the luminance images coupled with eye tracking enabled us to obtain the gaze-centred luminance fields, which gives a better estimate of actual luminance values perceived by the eye, used as a basis to investigate the gaze direction dependencies of visual comfort. This PhD dissertation describes different stages of conception of this novel dynamic discomfort glare assessment method. In the experimental phase, two pilot studies were made for proper integration of the adopted methods and techniques into discomfort glare assessments. Development of several routines, algorithms and tools to identify and translate the gaze directions in order to derive the actual luminance field perceived by the participants were needed to achieve this goal. A final comprehensive experimental phase was realised to investigate gaze behaviour in response to light. As a first validation step, the gaze-driven approach was compared to the fixed-gaze approach. Then the effects of different luminance levels as well as different view outside the window on the dynamic shifts of the gaze were investigated.The developed approach demonstrates the need to integrate gaze direction patterns into visual comfort assessments, which move us beyond the existing assumption of a fixed-gaze direction towards a gaze responsive comfort.

DAYLIGHT is a desirable architectural component that satisfies both visual and psychological needs of the occupants. Therefore it is essential to integrate this component in the design in a way that maximum daylight is guaranteed and a visually healthy and comfortable space is created. There are certain lighting situations that can reduce visibility and create dissatisfaction and visual discomfort in a daylit environment. Among different aspects of visual discomfort, discomfort glare is a phenomenon, which is less understood and is harder to quantify. BACKGROUND The studies concerning discomfort glare are mainly subjective based on measurements with conventional psychophysical procedures. These studies have resulted in a series of glare indices to predict the degree of discomfort caused by different light settings. PROBLEM The main assumption in the glare indices and defining position index is that the line of sight is fixed and focused on a specific point. In a natural experience of a space, line of view is not fixed and varies through time and space. Moving eyes and/or head scans the scene, which means the view direction is changing accordingly. The hypothesis is that there might be clear relations between the eye movement patterns and visual discomfort glare sensation. Daylit situation: Varying light conditions are created by setting four different facade configurations. The eye‐tracking method allows us to experimentally investigate the potential correlation of eye movement patterns to glare perception in a realistic scene. Very few studies so far have investigated the relationship between eye movements and building‐induced visual context, such as a window (Hubalek & Schierz, 2005; Surry et al., 2008). None went as far as connecting findings on eye movements to comfort perception. OBJECTIVES AND METHODOLOGY The objective of this study is to refine our understanding of dependencies of view direction as a function of light distribution. The eye‐tracking method is embedded in undesstanding glare. The experiment set up consists of a fixed office room layout and four daylight situations created by changing the façade configuration and an artificial light situation. Subjects are asked to perform a series of cognitive and non‐cognitive tasks including reading, memorizing, reproducing, resting and detection. Subjective glare assessments are also gathered.

A gaze-driven methodology for discomfort glare was developed and applied for glare evaluation. A series of user assessments were performed in an office-like test laboratory under various lighting conditions. The participants’ gaze responses were recorded by means of mobile eye tracking while monitoring photometric quantities relevant to visual comfort using HDR luminance imaging. The integration of the luminance images coupled with eye-tracking methods enabled us to use gaze-centred luminance distribution to have an accurate estimate of the light received at the eye. Using a novel gaze-driven approach, a unique database was created as a basis to investigate the gaze direction dependencies of visual comfort. Here we compare the proposed gaze-driven approach with two other approaches based on fixed-gaze assumptions: gaze fixating on the task area, and gaze shifted 45 ° towards the window area. The results show that there is a significant difference between luminance distributions driven by gaze and those based on fixed-gaze assumptions, indicating a potentially important impact on glare assessment results as well.

Discomfort Glare: - Focus on understanding discomfort glare - Embedding eye‐movement patterns in glare assessments - Refining glare position index. Problem: - The light of sight in glare position index is assumed to be fixed - In a natural experience, line of sight varies through time and space - This variation is due to light distribution and spatial configuration. How In an Experimental setting: - Subjective ratings and objective parameters are measured - Experiments are carries out in realistic and controlled work space.

Measuring gaze allocation during scene perception typically faces a dilemma: full control over the stimulus requires comparably constrained scenarios, while realistic tasks leave the visual input hard to control. We propose to capture the full (4pi) light-field of an oce space, while participants perform typical oce tasks. Using a wearable eye-tracking device ("EyeSeeCam"), gaze, head and body orientation are measured along with subjective well-being and performance. In the present study, 52 participants performed four oce tasks ("input", "reflection", "output", "interaction"), each with three dierent tools (phone, computer, paper) under varying lighting conditions and outside views. We found that eye and head were fundamentally differently affected by view and that this dependence was modulated by task and tool, unless participants' task was related to reading. Importantly, for some tasks head movements rather than eye movements dominated gaze allocation. Since head and body movements frequently remain unaddressed in eye-tracking studies, our data highlight the importance of unconstrained settings. Beyond assessing the interaction between top-down (task-related) and bottom-up (stimulus-related) factors for deploying gaze and attention under real-world conditions, such data are inevitable for realistic models of optimal workplace lighting and thus for the well-being of an occupant's workplace.

Despite numerous efforts in developing glare indices through human assessment studies, predicting visual comfort in indoor environments still poses important challenges in design. A major limitation in discomfort glare indices is that they all ignore its dependencies on view direction. In this study we adopted eye-tracking methods in a series of human assessment experiments in order to record actual visual response when experiencing discomfort glare. We set up an experiment where the view directions distributions were monitored as the participants were working in a side-lit office with three different task-supports - monitor, paper and phone - on a standardized office task sequence. The participants were allocated randomly to two groups where they were exposed to two different views from the window. The results show that the “view outside the window” is the main determinant of view direction bias whenever the participant is not focused on any cognitive or visual office task procedure.

Visual comfort is one of the main concerns for the integration of daylighting strategies in workspaces. Depending on the occupants’ seating position, light distribution in the field-of-view (FOV) can range from interesting highlights to visually discomforting situations which makes visual comfort highly dependent on dynamics of occupants’ view direction in the room. These undesirable situations, known as discomfort glare, have also been recognized as being the main drivers to change the façade setting. Considering the importance of daylight on human health, performance and spatial appraisal, it becomes clear that a reliable assessment of discomfort glare is critical in order to move towards performance-integrated daylighting design solutions in workspaces. There are several discomfort glare metrics that can be used at the design phase to predict discomfort glare risks. These metrics are basically drawn upon the same four physical quantities: the glare source luminance, size and position, and the general field of luminance that the eye adapts to. A major limitation, shared by all known glare metrics, is that the dependencies of glare on view direction are ignored and the calculated glare is only valid for a specific view-direction and seating position. This study seeks to eliminate this limitation through a deeper understanding of the dynamics of view-direction as a result of light variations across the FOV. The adopted methodology relies on experiments where the eye-movements of human participants are measured in a parameterized office-like room under day-lit conditions. The hypothesis is that there are clear view direction distributions patterns under different lighting conditions which will ultimately have a significant effect on evaluations of discomfort glare and lead to better integration of glare-free daylight solutions in buildings design.

Discomfort glare, among different aspects of visual discomfort is a phenomenon which is little understood and hard to quantify. As this phenomenon is dependent on the building occupant’s view direction and on the relative position of the glare source, a deeper knowledge of one’s visual behavior within a space could provide pertinent insights into better understanding glare. To address this need, we set up an experiment to investigate dependencies of view direction distribution to a selected range of brightness and contrast distributions in a standard office scenario. The participants were asked to perform a series of tasks including reading, thinking, filling in a questionnaire and waiting. The direction of their view was monitored by recording participants’ eye movements using eye-tracking methods. Preliminary results show that different facade configurations have different effects on the eye movement patterns, with a strong dependency on the performed task. This pilot study will serve as a first step to integrate eye-tracking methods into visual comfort assessments and lead to a better understanding of the impact of discomfort glare on visual behavior.

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. In order 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 in order 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.

This paper presents the results of an experimental study that aims to provide objective insights as to how luminance distribution in an office setting modulates our view direction (VD) in a daylit workspace while performing office tasks. Using the office-like test facility at Fraunhofer ISE (Freiburg, Germany) to create a range of controlled daylighting conditions, and a wearable mobile eye-tracker to measure eye and head orientation, we assessed VD distributions for subjects performing a standardized sequence of typical office tasks relative to two different daylight conditions: low contrast condition with no direct sunlight as compared to high contrast condition with direct sunlight coming into the room. Our results show that while the participants look more outside the window during a non-cognitive and non-visual office task, this effect is lower under the high contrast lighting conditions. Moreover, the focus of the VDs is on the task area when the participants are performing a task involving visual and cognitive activities.

While energy-efficiency or environmental measures have benefited from numerous and powerful research efforts, further research is needed to better understand the complex interactions between the many parameters influencing human comfort. Studies concerning discomfort glare, for instance, have so far been based on conventional psycho-physical procedures. Given the importance of discomfort glare in building performance, we will show how view direction dependencies of glare can be investigated by integrating eye-tracking methods. On the other hand, a strengthening of the connection between lighting conditions and human health will be discussed, based on collaborations with the scientists working in photobiology and neuroscience. The link between daylight and human circadian organization (as a proxy for health) is explored here in terms of its architectural implications for an increased understanding of the health effects of daylighting in architecture. Finally, visual interest in architectural daylighting refers to the aesthetic and perceptual aspects of a space’s illumination. The subjective nature of design makes indicators such as visual interest difficult to define, but a closer look at contemporary architecture suggests that there are certain similarities in how architects choose to choreograph daylight for varied programmatic needs and experiential effects.

For improvement of office space design, we intend to capture the full (4π) light-field of an office space, while measuring gaze, head direction, body position, blink rate, and pupil size along with task performance and subjective well-being during a variety of office tasks. Besides the immediate application aspects this will allow for the first time to have full control over task and visual input in a fully unconstrained real-world setting. In the study reported here, 52 participants performed office tasks that varied in the tools used (phone, computer, paper ) as well as in their mental load – input, output, reflection and interaction – and were recorded under various experimentally controlled lighting conditions and outside views. We analyze gaze allocation during these tasks, with a particular emphasis on the distinct roles of eye and head, as well as on the effects of discomfort glare.

This interdisciplinary research aims at addressing a question common to the fields of architecture, building technology and psychophysics: are there objective relationships between perceived comfort, occupant response patterns and lighting conditions? The prospect of getting a grasp on these relationships immediately opens up new opportunities for improved workspace design – towards higher productivity and performance – and for further investigations on well-being in built spaces and a deeper understanding of people’s visual response to their environment. The intent is to advance the state of the art in visual and thermal comfort assessment in interior spaces by including two new components: the relationship between lighting conditions and gaze patterns, and the impact of critical socio-cultural factors on perceived comfort. We will compare findings in two identical setups but that belong to very different overall contexts: one in Central Europe (Lausanne, Switzerland), one in the Middle East (Ras-Al-Kaimah, U.A.E.), so as to assess socio-cultural and climate-induced differences. We will thus extend the objectification of comfort criteria beyond environmental factors and beyond geographical or climatic boundaries. With lighting – and more specifically visual and thermal comfort - being a key issue for workplace-related health and productivity, our results are critical for workplace design, ergonomics and architecture in a sustainable world.

Existing methods for glare-free daylighting design rely on analyses of physically based lighting simulations employing tools such as Radiance. The rendered image is an accumulation of luminance values from a fixed point of view, which creates a basis for luminance-based metric analysis such as discomfort glare models. A major challenge using luminance images for glare prediction analysis lies in the image processing steps for deriving different parameters of the predictive discomfort glare metrics. One of these challenges is to define and identify glary pixels and zones in the image. The glare source detection algorithms adopted in evaluation tools like evalglare, search for pixels of luminance value that are x-times larger (we call it threshold multiplier in the following) than the average luminance of a pre-defined zone, e.g. the monitor screen. As a second step, the potential glare pixels detected within a search radius (also predefined) are considered and evaluated as one glare source. The implemented default value of a threshold-multiplier and the search radius are decided intuitively and so far no validation has been made on their accuracy. The objective of the present study is to establish a sensitivity analysis on the threshold and search radius parameters. In two series of experiments we took luminance images very 30 second under different lighting conditions and with different façade systems. We also gathered the participants’ subjective assessments of the glare conditions using a Likert scale. Thereafter, we processed the images using 15 different combinations for the threshold multiplier and search radius (threshold multiplier with 5 and search radius with 3 treatment levels). The preliminary results show that there is a significant effect of threshold on all lighting conditions and an effect of search radius on lighting conditions with shading systems. But the results also show, that the choice of the ”right” detection parameters underlies also some effects, which cannot be explained so far. The consequence of this is, that further investigations are needed and as long as no clear rule exist to choose ”right” detection parameters the user of glare evaluation tools has to check the detected glare sources for each investigated situation.

For the application of discomfort glare metrics, a categorisation is used, dividing the metric scale into categories of perception. These categories are separated by borderline values, or so-called cut-off values. Recent literature shows that these cut-off values are lower when they are derived from field study data than those derived from laboratory study data. To investigate this further, the data from one field study and two laboratory studies was used to derive and compare cut-off values corresponding to three borderlines. The results show that the field study cut-off values were systematically lower than the laboratory study ones, implying that discomfort glare is reported at lower stimulus magnitudes in the field. Although further research is required on that topic, several hypotheses are discussed in order to explain the gap between cut-off values derived from field data and cut-off values derived from laboratory data. Recommendations for future studies are also provided.

While architecture is composed of static structural elements, daylit space is perceived as a dynamic play of light and shadow – ephemeral qualities that add depth, texture, and movement to spatial composition. Our perception of architecture is greatly impacted by the intensity and geometry of natural light, which creates dynamic temporal effects through hourly and daily shifts in solar orientation. While most designers can agree that the composition of natural light is an important design consideration for the functionality, experience of, and comfort within architecture, daylight is most often evaluated for its ability to offset electric lighting use and promote energy efficient building practices. Using threshold illumination levels, most industry-standard metrics are concerned with evaluating whether there is sufficient illumination to conduct visual tasks and tend to promote a ‘more is better’ approach to lighting design - favoring uniformity over diversity and composition. While this approach is useful for measuring illumination requirements and evaluating daylight autonomy, there are limited metrics for evaluating the compositional factors of daylight and tools that can illustrate the ephemeral impacts of light and shadow as perceived by the human eye. The authors will present new performance metrics that are being developed to measure the compositional impacts of contrast in architecture, as perceived dynamically over space and time. Using high-dynamic-range renderings of an interior space located at 64°N, the authors will illustrate the dynamic visual effects of light and shadow through a short film. This film will document the daylight dynamics in two extreme conditions: the summer and winter solstices, drawing attention to the impact of latitude on our spatial perception of daylight. This presentation will combine cutting edge research in daylight analysis with stop motion film to communicate the power of light and shadow in our experience of architecture within a dynamic environment.

This thesis proposes a novel method for understanding occupancy in public indoor spaces by creating hybrid light-syntax zones, based on both simulated illuminance data and simulated configuration data. Yearly illuminance profiles and spatial syntax characteristics such as physical connectivity and visual integration were examined to develop zones which theoretically have similar occupancy rates to one another. To support the light-syntax zone concept, a case study was performed in a student cafe on a university campus. Occupancy and exterior light conditions were observed for thirteen days. Occupancy rates were mapped to each seat within the cafe and analyzed for correlations with the light- syntax zone data. A significant difference was found in the occupancy rates between different exterior light conditions (direct light present, rapidly changing/intermediate, diffuse light present) in the test cafe. A slight negative correlation was found between occupancy rates and integration and physical connectivity values, which seems to indicate that the cafe users are seeking out the most secluded spaces. However, higher illuminance values also show a correlation with higher occupancy ratios. Given the map of the space, it is possible that these two variables are confounded. Further studies are necessary to determine the validity of light-syntax zones as a tool for predicting relative occupancy within an indoor space.

This thesis studies the notion of responsiveness in architectural design. It tries to make a framework for understanding the act of response in architectural body. Focusing on Light as a contextual force, it studies the way light affects the built environment and architectural body, in order to introduce a light responsive system. This light responsive system will be used to design a mediatheque in the city of Geneva. Studying a multidisciplinary thematic between architecture and building physics this study is interested primarily to the architec- tural qualities of space. In parallel, it also considers the perfor- mance and comfort metrics. Two case studies in the third chapter are based on in-situation mappings and radiation analysis. The radiation calculations are done by Diva light simulator (based on Radiance software). The case studies are ordered considering the scale that they study; Their outcomes are used for the same-scale factors in a light responsive system proposed in the fifth chapter. In the chapter four the city and the program are reduced to quanti- tative design parameters to be used in the light responsive system. The term responsiveness is widely used in different disciplines. In the first chapter after a survey on these usages in different con- texts such as biology, social science and art, this study summarises a definition of responsiveness to found a framework for a light responsive system. Focusing on climate responsive systems and particularly light, in the second chapter, different approaches to use light as a form- giver for architecture are introduced. This chapter is devoted to the 6 questions such as :What are the spatial qualities of light and how lighting concerns affect architecture and design process? For introducing a light responsive system in the third chapter two case studies in two different scales are carried out. One studying the relation of light and the public space focusing on the urban promenades and the other one studying the relationship of interior light zones and the geometry; It searches for a lighting grammar in the interior space. Chapter four is devoted to analysis of the contextual and organisa- tional design problem parameters. As this study will be used later to solve a real design problem, in this chapter the objective is to propose simplified-well-behaving models of the urban context : the city of Geneva and the program: Mediatheque for the light respon- sive system. Chapter five proposes the characteristics of a light responsive sys- tem, considering all the design problem parameters.