Visual comfort research
INAHE CONICET, Mendoza, Argentina, 2018.
Glare metrics and validation & Building projects: facades and zero energy buildings
Universidad Catolica de Chile, Santiago de Chile, 2018.
How to Evaluate the « Performance » and « Robustness » of Glare Metrics?
CIE Expert Tutorial and Workshops on Research Methods for Human Factors in Lighting, Copenhagen, DK, 2018.
Making Simulations More Colorful: Extension of gendaylit to Create a Colored Sky
17th International Radiance Workshop, Loughborough, UK.
Défis et opportunités de l’interdisciplinarité en architecture
Journée de l’Architecture et de l’Urbanisme – Neuchâtel (JAU-NE), Neuchâtel, Switzerland, April 27, 2018.
Invited speaker for, , : “”
Embracing daylighting dynamics in human-driven design
SimAUD 2018 – Symposium on Simulation for Architecture and Urban Design, Delft, The Netherlands, June 4-7, 2018.
at , Delft, The Netherlands, June 4-7, 2018: “”
Velux Outreach Lectures, Zurich, Switzerland and Copenhagen, Denmark, November 7-8, 2017.
Towards human-centric lighting for office buildings. Pilot study on the interactions of visual, perceptual and non-visual effects of workplace (day)lighting
Society for Light Treatment and Biological Rhythms 29th Annual Meeting, Berlin, Germany, June 23-25, 2017.
Although knowledge about the impact of light on individuals beyond vision is becoming substantial and less and less controversial, there is still a gap on how to properly address what type of lighting quality one should seek in an indoor space. What constitutes good lighting conditions from a truly holistic, human-centered perspective, i.e. encompassing both visual and non-visual aspects? Very few models are currently available to embed non-visual lighting in a design decision-making process beyond the ability to compare how effective different sources are expected to be in generating non-visual effects. The aim of this study is to make a first attempt to test whether the non-visual system may constitute a dominant driver for determining the quality of lighting conditions in a working context and how it seems to interact with visual factors.
Confort Intérieur et bien-être : un regard vers le futur de l'habitat
Etablissement Cantonal d'Assurance (ECA), Bois-Chamblard, Switzerland, May 12, 2017.
Alerted by architecture. Non-visual responses to (day)light in office buildings
7th VELUX Daylight Symposium, Berlin, 3-4 May 2017.
WORKSHOP - Measurement of luminance distributions in the field of view for glare evaluations
“Smarter Lighting for Better Life” at the CIE Midterm Meeting 2017 - in Discomfort Glare Evaluation for Daylight and Artificial Light workshop, Jeju, South Korea, October 23 - 25, 2017.
Investigation of different subjective response scales for thermal comfort analysis: Likert-type and visual analogue scales
Perception of thermal comfort and pain - are we assessing their dynamics right?, Heidelberg, Germany, November 9-10, 2017.
Within the framework of a study investigating interactions among indoor environmental factors, two experiments were conducted on the effects of visual stimuli on thermal perception. Thermal responses were recorded with two methods, one quantitative via physiological measurements and a subjective one using a questionnaire. The questionnaire was developed on the basis of the standard EN ISO 10551 (2001-06-01) and recent publications on thermal comfort –. Two types of measurement scales were used, i.e., Likert-type and visual analogue. The first type was used for the questions about the thermal sensation, thermal comfort and thermal preference of the subjects and for the thermal sensation of their body parts (hands, feet and body). The only visual analogue scale in the questionnaire referred to the acceptability of the local climate in the room where the experiment was conducted. Different outcomes were recorded for the survey questions as they assess different aspects of thermal perception, confirming the outcome of previous studies , . The comparison between Likert- and visual-analogue scales shows a much broader variety of responses for the visual analog scale. We assume that this is due to the nature of the measurement technique that allowed fine-tuned judgement of the indoor climate on a scale from 0 (acceptable) to 100 (unacceptable). The Likert-type scales of the other questions, on the other hand, gave the chance to choose only among five or seven fixed answers, leading to responses much more restricted around particular values. As an outcome for the specific topic of our research (i.e., the study of interactions between visual and thermal factors), investigating in general small effect size, we argue that a measurement scale leading to a bigger variety of responses is more suitable. The development of a single value incorporating several responses from different questions is currently under discussion.
Temperature-colour interaction: is colour affecting people’s thermal perception?
Colour Research Day, Lausanne, Switzerland, October 23, 2017.
Over the last century, a large number of studies has tried to answer to the question whether coloured stimuli could have an effect on human thermal perceptual evaluation (i.e., temperature-colour interaction). In the building research area, this effect is referred to as the “hue-heat-hypothesis” (HHH) and has gained attention due to the fascinating idea of heating and cooling with colours. After a brief digression on previous studies on HHH, this presentation focuses on two experimental studies carried out recently at LIPID, EPFL. In both studies, temperature and colour are manipulated to assess the thermal evaluation of people taking part in the experiment. In the first study, colour is changed thanks to coloured filters applied on the windows of a test room, resulting in transmitted “coloured” daylight. In the second study, projected HDR photographs of the same room are displayed in the Virtual Reality headset, to control for the variability of daylight through time of the day and weather experienced in the first study. Results of both experiments confirm that colours have an effect on thermal perceptual evaluation of people, with blue leading to a “cooler” sensation and orange to a “warmer” one.
Effects of visual and thermal stimuli interactions on comfort perception
7th VELUX Daylight Symposium, Berlin, Germany, May 3-4, 2017..
In industrialized countries, people spend on average 85-90% of their time indoors (1). For this reason, major efforts are being made to understand and control the factors which affect people’s comfort, health and well-being inside buildings (2). The indoor environmental quality is characterized by four main parameters, i.e., indoor air quality, acoustic ambience, visual and thermal conditions. The human senses allow people to perceive the environment and estimate their comfort and acceptability with respect to these four indoor environmental factors. For this reason, the evaluation of indoor comfort requires a thorough understanding of how humans (intended as beings characterised by a body and mind) perceive and respond to these environmental parameters (3). Over the last century, studies have considered only one single factor at a time of the indoor environment with the aim to identify relationships between the single component and human comfort. These studies resulted in comfort models (e.g., thermal comfort) (4), standards, guidelines (5–8) and quantitative indices (9) which provided threshold values for light, temperature, noise and air quality. Current building design and technologies devoted to control the indoor environment are designed on supposedly independent effects of visual, thermal and other factors (10). Yet, human sensory systems are not modular, but integrate and respond to environmental factors simultaneously. Moreover, such environmental factors commonly occur in combination. It becomes clear that no single parameter of the indoor environment can be evaluated on its own. Thus, to improve our understanding of the influence of environmental parameters on human responses and perceptions in indoor environments, it is necessary to study their combined effects. Predicting the integral building performance in terms of comfort is a complex task. For this reason, to progress with global comfort knowledge it is necessary to start with the study of the interactions of two factors at a time (11). This Ph.D. research focuses on the interaction between visual and thermal stimuli on comfort perception and performance by means of experiments in an office-like test room in EPFL campus and validation in field studies. In particular, it analyzes the effect of visual variables on the perceived thermal comfort and of thermal variables on the perceived visual comfort, beside their interactive influence on performance. Three different experiments are planned, analyzing the mutual influence of the following parameters on thermal and visual comfort perception: (i) coloured daylight and temperature, (ii) illuminance level and temperature (iii) glare and temperature. The first experiment about the influence of coloured daylight on thermal comfort perception and of temperature on colour acceptability and preference has started in November 2016.
Daylightful indoors: designing with visual and non-visual light
"Jeudi de Jules Gonin" Symposium on Chronobiology, Hôpital Ophtalmique, Lausanne, Switzerland, June 29, 2017.
Perceptual daylighting – bridging research and practice
Carpenter Design Associates, New York, USA, April 6, 2017.
Confort et bien-être au coeur de l’habitat: un futur radieux
Rencontres La Foncière 2017 conference on tomorrow’s habitat, Hotel Savoy, Switzerland, June 14, 2017.
Material Light: bringing the outside in
Material Light ::Light Material Symposium, Yale University, New Haven, USA, April 7-8, 2017.
Dynamics of daylighting inside out
7th Velux Daylight Symposium, Berlin, Germany, May 3-4, 2017.
Daylighting is by nature a multi-dimensional quality in a space. It reveals its volumes and surfaces in a dynamic way, influences visual interest and enables visual performance while also constraining it, and has physiological and behavioral impacts on the space’s occupants. All these effects need to be brought together to lead to a satisfying space design and experience with one recurring question : how to best balance the resources we have available (solar radiation, energy, climate, natural or built surroundings) to fulfill, at minimum and beyond, occupants’ physiological and emotional needs. These needs are themselves multifaceted as building occupants interact with their environment in many different ways: as users of a (work)space who perform tasks for which comfortable visual and thermal conditions are needed, as witnesses of a delightful space who want to enjoy it and seek to experience its choreography of geometry and light dynamics, as human inhabitants of a living space who need to be in an environment conducive to health, as beneficiaries of the planet’s resources concerned about minimizing energy loads associated with buildings, whether for lighting, heating or cooling. The challenges we face are thus numerous in aiming for « good daylighting ». Trade-offs have to be found to limit visual discomfort while ensuring sufficient light exposure although we still don’t know how much exposure to light we actually need over a day, or a week, or a season to fulfill our physiological needs. We also have to embrace emotional aspects of daylight in our quest for better solutions, and thus broaden the range of performance predictors by including perceptual qualities in a consistent way. Spectrally and time-dependent, human-centric, field-of-view based and immersive approaches to investigating daylight performance seem highly promising to address some of these challenges.
Challenges and opportunities of interdisciplinarity : insights from human-centric building research at EPFL
Building Technology Lecture Series, MIT, Cambridge, USA, April 6, 2017.
Interdisciplinarity has become an inherent component of most research and education developments nowadays. It brings with it new challenges, from how to share a common language to how to avoid becoming generalists, as well as new opportunities in solving more complex problems through disciplinary complementarities. This is particularly true in building research, where a high diversity of skills, mindsets and approaches is needed to bring further advances to the field. This talk will discuss some specific initiatives at EPFL on growing a culture of interdisciplinarity and building synergies between traditionally distinct fields, especially in relation to the built environment. To provide building designers with the means necessary to assess critical parameters in a successful design and efficiently combine qualitative and quantitative criteria in the solution search process, we need to work from what we have and from what we need. This is true at the human occupant’s as much as at the urban environment’s scales : the recurring question one has to address in any of these contexts is how to best balance the resources we have available (solar radiation, energy, climate, natural or built surroundings) to fulfill, at minimum and beyond, our human needs, which range from well-being and comfort, to health and emotional delight, but also to social quality.
Indoor lighting environments: perceptual dynamics and occupant response
Light” Chronobiology workshop, Hôpital Ophtalmique, Lausanne, Switzerland, April 2017.
Daylighting and building performance: Towards user-centric living environments
Cercle International - Fondation pour Genève, Geneva, Switzerland, March 15, 2017.
Physiological, visual and perceptual dynamics of daylighting
BASF-CSEM seminar, Basel, Switzerland, May 27, 2016.
Natural Light for Modern Architecture
CSEM annual event “Light for Life”, Neuchâtel, Switzerland, April 26, 2016.
Energie, environnement naturel et construit à l'EPFL: à l’intersection de thématiques de recherche aux facettes multiples
GazNat General Assembly, Montreux, Switzerland, June 8, 2016.
Sustainable Habitats – reconciling what we need with what we have
ESA Closed Habitats Forum, Lausanne, Switzerland, June 10, 2016.
Efficient daylighting and solar control strategies can have a tremendous impact on energy use. But any savings can only be effective if one also carefully accounts for our comfort, well-being and health criteria. This talk will explore current research efforts at the interface between architecture and building technology, with a focus on the integration of building performance in design especially as far as daylighting and passive solar strategies are concerned. We need more efforts to provide building designers with the means necessary to assess critical parameters in a successful design and efficiently combine qualitative and quantitative criteria in the solution search process. This must be approached from two perspectives: from what we have and from what we need. We of course must analyse the resources available to work with (i.e. the building’s environment whether natural and/or built, its localisation, climate etc) and process this information to inform us about how the building should respond to it; but first, we have to identify the needs of the building’s occupants, to determine whether and how these can be met. Taking the perspective of ongoing research in these fields, this talk will more specifically explore the impact of natural lighting contributions on occupants well-being, notably from their health and biological clock perspective, as well as the perceived visual and thermal comfort, which are considerations that should be at the heart of human acceptable habitats whether on earth or in enclosed conditions further away. The recurring questions one has to address in any of these contexts is how to best balance the ressources we have available (solar radiation, energy, climate, natural or built surroundings) to fulfill, at minimum and beyond, the occupants’ needs.
Sustainable Building Design the challenges of interdisciplinarity
Teaching Sustainability Symposium, Academy of Architecture, Mendrisio, Switzerland, October 11 & 12, 2016.
Roundtable on Future of Switzerland
15th Venice Architecture Biennale - The Horizontal Metropolis, Certosa Island, Venice, Italy, November 26, 2016.
Daylighting performance: a dynamic and multidimensional challenge
Public annual Light Lectures #9: Creating knowledge on light – combining scientific fields, Aalborg University AAU, Copenhagen, Denmark, November 2, 2016.
Invited keynote speaker
Research, teaching, leadership … What are the demands on today’s professors?
Swiss National Science Foundation Networking event 2016, Bern, Switzerland, January 2016.
Invited round table panelist on the occasion of the programmes' 15th anniversary, organized by the Réseau romand de mentoring pour femmes and Mentoring Deutschschweiz
Immersive scenes with Radiance in a Virtual Reality Headset: comparison of virtual and real environments
15th International Radiance Workshop, Padova, Italy, August 29-30, 2016.
This presentation introduced a novel method for creating immersive scenes for Virtual Reality based on physically-based renderings and discussed the potential and limitation of this method.
Smart Cities – Pour relever les défis d’urbanisation et de mobilité du futur
Swisscom Dialog Forum, Lausanne, Switzerland, June 19, 2015.
EPFL Fribourg et le smart living lab
Chambre de Commerce et de l’Industrie Fribourg (CCIF), Fribourg, Switzerland, March 2015.
Perceptual, comfort and health aspects of natural lighting in a space
Swissphotonics / LASSIE-FP7 workshop on “Smart Lighting”, EPFL, Lausanne, Switzerland, October 2015.
This presentation will explore the multifaceted nature of daylight performance in architectural spaces by discussing ongoing research regarding the dynamics of daylighting performance considering three interpretations of “well-being” in a space: as a human inhabitant of a living space, as a user of a (work)space, and as a witness of a delightful space.
Et lux fuit – les apports de l’éclairage naturel au bien-être des habitants
"Journées du Logement 2015" of the Office Fédéral du Logement OFL, Granges, Switzerland, November 2015.
Un éclairage naturel efficace et des stratégies de contrôle solaire peuvent avoir un impact énorme sur la consommation d’énergie. Mais toute économie d’énergie ne peut être efficace que dans la mesure où elle satisfait également nos exigences en matière de confort, de bien-être et de santé. L’exposé présentera les efforts de recherche actuels à l’interface de l’architecture et des technologies de la construction et mettra plus particulièrement l’accent sur l’intégration des exigences techniques en matière d’éclairage naturel et de solaire passif aux qualités architecturales du bâtiment.
Sustainable Social Housing in Temperate Areas. Italy and Brazil: the use of vegetation as a retrofit strategy
Invited seminar at the Department of Architecture of the University of Palermo, Palermo, Italy, May 22, 2015.
Contemporary cities are more than ever committed to tackle environmental challenges such as the attenuation of the urban heat island phenomenon and the renovation of a large building stock characterized by low indoor comfort levels and increasing energy consumption caused by air conditioning. The presentation aims at contributing to the debate of Social Housing renovation in temperate areas, with a focus on the use of vegetation as a possible sustainable and cost-effective strategy. Through the analysis on a real case of Social Housing in the city of Palermo (Italy), a simulation based method for the design and assessment of the benefit of plants and BIV systems is presented.
The integration of vegetation in the built environment: strategies and technical alternatives for the optimization of the building envelope
"L’innovazione dell’involucro edilizio", sponsored by Buffa srl and the Professional Association of Architects of Trapani, Alcamo, Trapani, Italy, October 10, 2015.
The presentation provided an overview on the main environmental benefits derived from an adequate integration of vegetation in the built environment, especially in terms of microclimate mitigation and indoor thermal comfort. In particular, the main technological systems for Building-Integrated Vegetation were presented, by showing their technical features in some emblematic buildings.
Architectural strategies to integrate wellbeing and health effects of daylight into the design of primary schools: a comparative analysis of exemplary case studies
VELUX Daylight Academic Forum, London Metropolitan University, United Kingdom, Sept. 2015.
Starting from an architect’s point of view, the aim of this research is to combine the daylight performance of educational spaces with a broader spatial, cultural, and historical approach. Through a rigorous study of school typologies, the geometry of their spaces, and their associated daylighting strategies, this work aims to connect design practitioners with aspects of health and well-being for the pupils, as far as these aspects are related to the quality of daylight. The proposed methodology seeks to analyse a range of outstanding case studies from the masters of modern architecture, embodying architectural strategies specifically designed to ensure adequate illuminance levels in learning areas throughout the day. A selection of some singular primary schools will be established through a historical analysis which emphasizes the impact of hygienists’ principles – legacies of Modernism – on the evolution of plans and volumes of different school typologies in Switzerland and Europe, from 1945 to the present days. An analysis of the selected case studies will be carried out using an innovative representation method of average illuminance received at eye-level and combined with a HLR model – currently under development at LIPID [1, 2] – which assesses the health potential of daylight using a dynamic approach. Through a validation of the simulated results using different in situ measurements and analyses following a specific protocol, we aim to accurately identify architectural criteria and propose strategies for achieving “circadian design”, more specifically those having a positive impact on the health and wellbeing of occupants. We will also carry out a comparative critical assessment of the buildings selected as case studies in the initial phase of this proposed research. The goal is to positively influence decisions related to the design of naturally lit spaces, specifically in schools and according to their impact on health, wellbeing and student productivity. The methodology will be a complementary blend of observations, in situ measurements and qualitative and quantitative analyses, both in a simulated environment and in actual working conditions of the selected case studies.
Experiencing a daylit space
6th VELUX Daylight Symposium, London, September 2-3, 2015.
To embed the diversity and variability of human needs as foundational elements of daylighting design and put human occupants back at the core of the building question, we need to reach out to fundamental discoveries from neuroscience, biology and other fields, which will bring new insights and a deeper understanding of how we interact with our environment. The multiplicity and variability of our needs regarding (day)light exposure have been a topic of investigation for years now in photobiology and psychophysics, though have not yet penetrated the design realm as dynamic models of human response. Humans need to be in an environment conducive to health and have physiological light exposure needs, whose time- and spectrum-dependent non-visual effects we only start to understand. On the other hand, users of a space often need to perform tasks for which comfortable visual conditions are needed, to which we respond with head and gaze dynamics that psychophysics can help us better recognize. Finally, any attentive witness to a space seeks to enjoy its play of light and dark. Perception of daylight is the primary interpreter of the materiality and dynamism of any architectural space. As a result, while daylight as a subjectively perceived visual effect is actually very hard to use as a design factor, it is often what drives decisions. It is time to bring these exciting new research perspectives back into the design realm in a way it can interactively, dynamically and effectively fuel the creative design process: we have access to the essential ingredients of human-responsive design, now we need to cook.
Implications of the interplay between light and dark for human health in the built environment
The Dynamics of Darkness in the North, Reykjavík, Iceland, February 26-28, 2015.
24-hour cycles of light and dark are one of the most significant factors in the built environment that affect human health and wellbeing. In addition to stimulating visual responses, light induces a range of circadian, physiological and behavioral responses in humans, including sleep quality, hormone production, alertness and cognitive performance. These nonvisual responses are primarily mediated via a novel type of photoreceptors that contain the photopigment melanopsin. These photoreceptors can function independently of the classical photoreceptors, rods and cones used for seeing, thus the human eye plays a dual role in detecting light. Since the overall purpose of lighting is to serve the needs of humans, the discovery of the melanopsin-containing photoreceptors should be addressed in architectural lighting design and engineering in buildings. The optimal daily doses of light and dark needed for synchronizing circadian rhythms or promoting other physiological and behavioral nonvisual responses are currently unknown, however there are evidences that light can have beneficial or harmful effects depending on the timing of the light exposure. Daytime light exposure can reduce sleepiness and improve performance but light exposure should be avoided at night, where it can suppress melatonin production resulting in circadian disruption. Human-centered approaches are rarely applied to evaluate building performance, where conventional recommendations for lighting are mainly based on the amount of brightness at a horizontal work plane. One of the challenges is to assess the amount of light received by occupants throughout the 24-hour day, whether the light source is daylight or electric. This paper summaries major implications of the interplay between light and dark for human nonvisual health in the built environment and discusses recent concepts that aim to integrate these findings into practice for supporting healthy lighting design.
Comparative performance assessment of parametrically generated variants of a masterplan: Case studies in Switzerland
Open Symposium on Solar Energy in Urban Planning, Trondheim, Norway, March 20, 2015.
We describe a methodology to parametrically generate several neighborhood design variants based on a master plan and comparatively evaluate their performance in terms of passive and active solar potential. Two case studies in Yverdon-les-Bains and Lausanne (CH) are presented.
The Dynamics of Shadow: Architecture of Natural Light in Extreme Latitudes
The Dynamics of Darkness in the North, Reykjavik Iceland, February 26-28, 2015.
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.
Glare Evaluation Tutorial
13th International Radiance Workshop, London, UK, September 1-3, 2014.
Smart Living Lab and beyond - outlook on building research
Rencontre au Sommet du Moléson, Moléson-sur-Gruyères, November 4, 2014.
Building occupants in the spotlight: health, comfort and visual dynamics in daylit spaces
EuroTech mini symposium, Eindhoven, The Netherlands, May 14, 2014.
To embed the diversity and variability of human needs as foundational elements of daylighting design and put human occupants back at the core of the building question, we need to reach out to fundamental discoveries from neuroscience, biology and other fields, which will bring new insights and a deeper understanding of how we interact with our environment. This talk will discuss how to bring exciting research perspectives regarding the assessment of daylighting performance by considering three interpretations of “well-being” in a space: as a human inhabitant of a living space, as a user of a (work)space, and as a witness of a delightful space.
Lumière sur le confort et la santé
Cycle de conférences "La Science expliquée", Delémont, Suisse, February 20, 2014.
Ingénieure physicienne spécialisée dans la lumière naturelle et les stratégies solaires passives pour les bâtiments, Marilyne Andersen a donné un aperçu de ses travaux de recherche sur les implications de la lumière naturelle sur le confort et la santé ainsi que sur les technologies à haute efficience énergétique pour des bâtiments. Dans une optique de recherche interdisciplinaire à l’interface entre les domaines du design architectural, de l’ingénierie du bâtiment et des sciences plus fondamentales, ces travaux ont permis d’ouvrir de nouvelles perspectives dans le développement et la coopération entre des domaines aussi éloignés les uns des autres que l’architecture, la photobiologie, la psychophysiologie dans le domaine de la vision et l’optique.
Building envelopes – A permeable interface for daylight and solar harvesting
Challenging Glass & COST Action Conference, Lausanne, Switzerland, February 6-7, 2014.
The ultimate impact buildings have on our lives is fundamental: buildings represent a major part of our life, with a share of over 40% of overall energy use, waste and CO2 emissions, almost 50% of the population now living in cities, and 90% of time typically spent indoors. With lighting being responsible for the greatest energy requirements in commercial buildings - that are also mostly used during daytime -, and with heating and cooling being the two second most energy-demanding building functions, it appears very clearly how efficient daylighting and solar control strategies can have a tremendous impact on energy use. But any savings can only be effective if one also carefully accounts for our comfort, well-being and health criteria. This talk will explore current research efforts at the interface between architecture and building technology, with a focus on the integration of building performance in design as far as daylighting and passive solar strategies are concerned.
Human Response in Daylit Spaces
Colour, emotion and well-being, Lausanne, Switzerland, November 21, 2013.
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.
L'enveloppe du bâtiment comme interface entre l'environnement et notre bien-être: approches passives et éclairage naturel
0-carbone dans l'environnement construit, Fribourg, Switzerland, November 20, 2013.
It is well known that a building's energy performance (heating and artificial lighting) and the comfort of occupants are very strongly correlated with a building envelope’s access to the sun and its ability to harness that resource. We need to determine how the climate interacts with the built environment, how buildings influence each other, and how the indoor environment is impacted by these. In addition, in order to achieve any objectives related to sustainability, it is far more effective to influence building design in its early phases than in its final ones. This presentation will provide an overview of how the combination of climate science, statistics, lighting and thermal analysis on optimizing the form of the built environment – from building massing to the specifics of façade technologies – can bring promising answers if properly translated into design recommendations and guidance.
Human-driven daylighting: research perspectives and outlook
Energy Forum on Advanced Building Skins, Bressanone, Italy, November 5-6, 2013.
A conference on advanced building skins was held in Bressanone, Italy on November 5-6, 2013. The main objective of this conference is to contribute to a multidisciplinary, integrated planning approach to sustainable buildings and to create a dialogue among architects, engineers, scientists, energy managers and manufacturers with the aim of reducing energy consumption while improving the comfort and health of building occupants.
Human needs as a driver for lighting design
Photon Project conference, London, UK, September 16, 2013.
Thanks to fundamental discoveries from neuroscience, biology and others, we have achieved a deeper understanding of how we interact with our environment. It is time to bring this knowledge back to architecture: we have access to the essential ingredients of human-responsive design, now we need to cook. This requires performance from a human needs standpoint to be considered from a radically new perspective, rooted in interdisciplinary bridging with other domains of fundamental science and inherently dynamic in both the dialog established with the designer and the way diversity and variability of human needs are accounted for. This perspective asks us to move away from evaluating performance as an absolute value ranging from good to bad, because the concept of performance itself becomes dynamic: performance should be measured against goals that might vary over time (variability), by occupant profile (diversity) and/or be subjective (designer’s intent). Daylighting provides an ideal topic of investigation for this quest because of its strong impact on human health and well-being, its close association with (subjective) emotional delight and perceived quality of a space, and its highly dynamic and variable nature derived from a combination of predictable (sun course) and stochastic (weather) patterns.
Sun, Light and Space
WISH Pecha Kucha, Lausanne, Switzerland, September 2, 2013.
As a building physicis engineer specialized in daylighting and passive solar strategies for buildings, Marilyne Andersen provides an overview of her pioneering work in comfort and health implications of daylight, and on low-energy building technologies. With a clear interdisciplinary research focus at the interface between the domains of architectural design, building engineering and more fundamental science, she has opened new development and cooperation perspectives between fields otherwise as remote from design as photobiology, vision and eye-tracking research, and optics.
New Eyes on Existing Buildings
Symposium Moderator for 5th Velux Daylight Symposium, Copenhagen, Denmark, May 15-16, 2013.
On May 15-16, 2013 the 5th International Daylight Symposium, themed « New Eyes on Existing Buildings » and organized by Velux, took place at the Royal Academy of Arts in Copenhagen, Denmark. It was preceded by the 2nd Academic Forum for PhD students working on daylighting issues on May 14. Prof. Marilyne Andersen, head of the LIPID laboratory at EPFL, was invited as moderator for the whole symposium and as leading scientific researcher for the Academic Forum.
Energy potential and interactive design in the urban context
ENAC Research Day, EPFL, Lausanne, Switzerland, June 15, 2012.
Despite the numerous existing design tools developed to support practitioners achieve energy performing buildings, practical use of those tools remains limited, in particular due to their restricted integration into the design process. This project is motivated in particular by the lack of interactive design-oriented tools able to provide guidance at the early design stage of urban districts. The proposed approach consist in the development of a support methodology based on improving the solar potential of an urban district design, considering the inter-building influence. By progressively proposing modifications of key variables (e.g. orientation) leading to a better performance as in a dialogue with a ‘virtual consultant’, the user shall gain insight into the energy considerations of the design.
Designing with Daylight: Integrating performance within the human and environmental contexts
99th Annual Congress of the Swiss Society of Surgery, Davos, Switzerland, June 21, 2012.
In the contemporary context of building for sustainability, architects are faced with a major challenge of reconciling a vast range of human requirements within a successful design that has to answer ecological constraints. Within the overall framework of promoting linkages between the engineering and design fields, this talk will discuss new approaches in research and education that are being developed to better integrate building performance considerations in the architectural design process. Daylighting is chosen as a strategic focus for this effort, being inherent to architectural design and one of the main drivers of a building's technical performance and resulting human comfort and health.
Lighting and human needs in built spaces
Kickoff meeting at James Carpenter Design Associates, New York NY, USA, March 29, 2012.
This presentation will discuss how recent findings in photobiology about the correlation between lighting and the human circadian system can prospectively be applied to architectural design, with a focus on healthcare and housing environments. Outcomes of photobiology research were used to define threshold values for illumination in terms of spectrum, intensity, and timing of light at the human eye, and were translated into goals for simulation – and ultimately for building design. While no actual recommendations can - or should - yet be made because of our limited understanding of the effects of exposure to light on human health and circadian organization, especially during daytime, we can still discuss the relevance of some critical design parameters to electric lighting or – to a greater extent – to daylighting.
La performance au service de l'architecture: nouvelles perspectives de recherche à l'EPFL
Rotary Club, Lausanne, Switzerland, February 17, 2012.
This talk provides an overview of the current research projects at LIPID and the necessity for performance-integrated design in today’s urge for energy-efficient, human-responsive living spaces. Within the overall framework of promoting linkages between the engineering and design fields, new approaches in research and education that are being developed to better integrate building performance considerations in the architectural design process are discussed, with a strategic focus on daylighting. LIPID’s research areas range from new façade technologies to interactive visualization methods or climate-based performance metrics with a common overarching goal of promoting energy-efficiency and human comfort and health within buildings. Ongoing projects include new calculation methods, evaluation tools, instruments and metrics that aim to support this integration effort in the course as well as the lab environments.
Solar shading and its influence on daylight and well-being
R+T 2012, Stuttgart, Germany, February 29, 2012.
This talk will provide current research perspectives on shading systems, on how their performance can be evaluated and on what the implications are on comfort and health. In particular, the latest results from an ongoing research project conducted at the LIPID to create a ranking system that applies to any façade system that is considered to be a complex fenestration system will be presented. This evaluation process currently relies on three metrics, each being associated to one aspect of the potential benefits of a window system that usually get very variable priority levels depending on the system and the space use, namely energy conservation potential, visual comfort potential and potential for view.
Performance at the service of architecture
Inaugural lecture at EPFL, Lausanne, Switzerland, February 24, 2011.
Designing spaces that are able to balance human comfort, energy-efficiency and well-being in a given climate is a real challenge, yet a problem faced every day by architects and building designers. Within the overall framework of promoting linkages between the engineering and design fields, this talk will discuss new approaches in research and education that are being developed to better integrate building performance considerations in the architectural design process. Daylighting is chosen as a strategic focus for this effort, being inherent to architectural design and one of the main drivers of a building's technical performance and resulting human comfort and health. The talk will present research and teaching perspectives for the recently founded Interdisciplinary Laboratory for Performance-Integrated Design (LIPID), which include new calculation methods, evaluation tools, instruments and metrics that will support this integration effort in the course as well as the lab environments.
Daylight Performance to Inform Architectural Design
4th Velux Daylight Symposium : Daylight in a Human Perspective, Lausanne, Switzerland, May 4-5, 2011.
LIPID’s research areas range from new façade technologies to interactive visualization methods or climate-based performance metrics with a common overarching goal of promoting energy-efficiency and human comfort and health within buildings. Ongoing projects include new calculation methods, evaluation tools, instruments and metrics that aim to support this integration effort in the course as well as the lab environments. Daylighting is chosen as a strategic focus, being inherent to architectural design and one of the main drivers of a building's technical performance and resulting human comfort and health.
Comfort and Technologies: From the Individual’s Needs to Cleantech
Swiss – Emirati Friendship Forum: UAE-Swiss Research Day 2011, Lausanne, Switzerland, June 22-23, 2011.
The Interdisciplinary Laboratory of Performance-Integrated Design (LIPID) is one of the two (ultimately five) ‘mirror’ labs for the EPFL Middle East campus. Synergistic research and education initiatives are being developed with a focus on climate as a driver for building envelope performance. Research at the interface between design and performance is of primary interest in today’s energy and environmental context in Western countries and cool-temperate to warm-temperate environments. But it is even more critical in a hot-arid climate that imposes extreme environmental conditions and where overly glazed envelopes pose particularly serious comfort and energy issues.
Integrating energy-efficient and human-responsive daylighting considerations in the architectural design process
swissnex San Francisco lecture series ‘Light Beyond Vision’, San Francisco CA, USA, February 16, 2010.
How to integrate Climate Engineering & Façade Design
Energy Forum 2010 Conference, Bressanone, Italy, December 2010.
Delight in Greener Daylight – A Teacher’s Perspective
Opening of exhibition ‘Delight in Greener Daylight", MIT Wolk Gallery, Cambridge MA, USA, April 27, 2010.
Lightsolve – An Interactive Climate-Based Simulation Tool for Early Stage Daylighting Design
Lightfair 2010 (Daylighting Institute Workshop), Las Vegas NV, USA, May 2010.
Natural Light in Design: Challenges and Research Perspectives
UC Berkeley, Center for the Built Environment, Berkeley CA, USA, March 2009.
Bringing Daylight Indoors: Benefits, Challenges and Research Opportunities
Saint-Gobain HQ, Aubervilliers, France, May 2009.
Prospective Design Implications of Recent Findings in Photobiology
3rd VELUX Daylight Symposium, Rotterdam, The Netherlands, May 2009.
Designing with Daylight: Incentives, Challenges and Research Perspectives
School of Architecture, Civil and Environmental Engineering conference cycle, EPFL, Lausanne, Switzerland, May 2009.
Light and the Circadian System – State of the Art and Applications to Design
Lightfair 2009 (Lighting Institute Seminar – 1.5 hours course), New York NY, USA, May 2009.
Complex Fenestration Systems Properties and Window and Building Performance Metrics
Complex Glazings Workshop at the Lawrence Berkeley National Laboratory, Berkeley CA, USA, June 2009.
Incorporating non-visual effects of light into architectural design
American Society for Photobiology Topical Symposium (Lighting, Architecture and Human Health Workshop), Philadelphia PA, USA, July 2009.
Designing with Daylight: Incentives, Challenges and Research Perspectives
Boston Society of Architects (Building Enclosure Council), Boston MA, USA, September 2009.
Daylight in Design: Benefits, Challenges and Research Opportunities
International Congress of Architecture ‘Luz & Diseño’ (Light and Design), Instituto Tecnológico y de Estudios Superiores, Monterrey, Zacatecas, Mexico, October 2009.
Architectural Implications of Circadian Daylighting
2009 IES Annual Conference "Realizing the Future - Research to Application", Seattle WA, USA, November 17, 2009.
Natural Light in Design: Research Perspectives and Technological Challenges
Rensselaer Polytechnic Institute, Troy NY, USA, April 2008.
Daylighting Research Program at MIT: projects and perspectives
Lawrence Berkeley National Laboratory, Berkeley CA, USA, May 2008.
Increasing Useful Daylight: Promising Systems and Technological Challenges
Lightfair 2008 (Lighting Institute Seminar – 1.5 hours course), Las Vegas NV, USA, May 2008.
Daylight Simulation: Today and Tomorrow
AIA 2008 National Convention, Boston MA, USA, May 2008.
Daylighting Design, Performance and Technology: Some Research Perspectives at MIT
Fraunhofer Institut für Solare Energiesysteme (Fhg-ISE), Freiburg, Germany, June 2008.
Daylight-Responsive Design: Challenges and Research Perspectives
Université Catholique de Louvain (UCL), Louvain-la-Neuve, Belgium, June 2008.
New Developments in Building Technology and Efficiency
Inaugural Energy Fellows Symposium organized by the MIT Energy Initiative (“Innovations” session), Cambridge MA, USA, September 2008.
Measuring daylighting effects beyond glass: façade, walls, ceilings…
Saint-Gobain Innovation Day themed “Solutions for Non Residential Buildings”, Newton MA, USA, September 2008.
Increasing Useful Daylight – Promising Systems and Technological Challenges
3M Center, St. Paul MN, USA, November 2008.
New Research Perspectives in Daylighting at MIT
Renewable Energy Seminars of the School of Architecture, Civil and Environmental Engineering at EPFL, Lausanne, Switzerland, February 2007.
Natural Light in Design (3-hour workshop) and Daylighting in Architecture: art, science and economics (1.5 hour session)
NESEA conference Building Energy 07, Boston MA, USA, March 2007.
Light-redirecting materials : their potential, characterization and applications in lighting control
Lightfair 2007 (Lighting Institute Seminar – 1.5 hours course), New York NY, USA, May 2007.
Lighting Systems: Challenges Ahead for an Optimal Use of Natural Light
Green Building Workshop organized by Corning Inc, Corning NY, USA, July 2007.
Advanced Daylighting Systems: Challenges Ahead for an Optimal Use of Natural Light
Architectural Record Innovation Conference 2007, New York NY, USA, October 2007.
Daylighting Research perspectives at MIT
NESEA conference Building Energy 06, Boston MA, USA , March 2006.
Daylighting at MIT: why, what and how…
MIT-Lausanne Concert Choir Science Lecture Exchange (From Lausanne to MIT: International Lecture Symposium), Cambridge MA, USA, April 2006.
Advanced Sun Control
Lightfair 2006 (Daylighting Institute Workshop – 3 hours course), Las Vegas NV, USA, May 2006.
Daylighting simulation workshop (2 hours course) and The LightSolve Project (session “Simulations of daylighting, acoustics and structures”)
IBPSA-USA (SimBuild2006: Building Sustainability and Performance through Simulation), MIT, Cambridge MA, USA, August 2006.
A New Daylighting Laboratory at MIT
Building Technology Lecture Series of MIT, Cambridge MA, USA, October 2006.
Daylighting at MIT: why, what and how…
LFEE Seminar on Energy and Environment of MIT, Cambridge MA, USA, November 2006.
Innovative bidirectional video-goniophotometer for advanced fenestration systems
Fraunhofer Institut für Solare Energiesysteme (Fhg-ISE), Freiburg, Germany, April 2004.
Innovative bidirectional video-goniophotometer for advanced fenestration systems
TNO Construction and Research, Delft, The Netherlands, May 2004.
New Research Perspectives in Daylighting
Building Technology Lecture Series at MIT, Cambridge MA, USA, October 2004.
Light distribution through advanced fenestration systems
Building Technology Group at MIT, Cambridge MA, USA, June 2003.
Ray-tracing simulations for the assessment of complex fenestration systems
Building Technologies Department seminar series, Lawrence Berkeley National Laboratory (LBNL), Berkeley CA, USA, June 2002.
Ray-tracing simulations for the assessment of complex fenestration systems
Solar Energy and Building Physics Laboratory seminars at EPFL, Lausanne, Switzerland, September 2002.
Propositions for the assessment and use of complex glazing materials' optical properties
Building Technologies Department seminar series, Lawrence Berkeley National Laboratory (LBNL), Berkeley CA, USA, September 2001.
Mesure des propriétés photométriques bidirectionnelles d'éléments de vitrage par imagerie numérique
Solar Energy and Building Physics Laboratory lecture series, EPFL, Lausanne, Switzerland, January 1999.
Contrast Glare and visual comfort in response to daylight
7th VELUX Daylight Symposium, Berlin, Germany, 3-4 May 2017.
There are uncertainties in the current daylight glare prediction models as they do not accurately predict the glare sensation that people experience. The objective of this research project is to investigate daylight glare stemming from contrast between task area and its immediate surroundings. In order to control for bias, several of the main factors that are suspected of influencing individuals’ glare ratings will also be investigated, among others self-reported glare sensitivity, gaze direction and eye contrast sensitivity. The expected research outcome is an improvement of the current daylight glare prediction models.
HDR Images for Glare Evaluation: Comparison Between DSLR Cameras, an Absolute Calibrated Luminance Camera and a Spot Luminance Meter
“Smarter Lighting for Better Life” at the CIE Midterm Meeting 2017, Jeju, South Korea, October 23 - 25, 2017.
User calibrated digital single-lens reflex (DSLR) cameras, utilizing an automated image calibration algorithm, are being used for glare evaluations as affordable alternatives to high-end luminance cameras calibrated by manufacturers. This study investigates the accuracy of luminance maps derived from HDR images captured with auto-calibrated DSLR cameras. More specifically, to compare the luminance values obtained with an auto-calibrated DSLR camera with a commercially available camera (that benefited from an absolute calibration) and a handheld luminance meter, considered as the reference. It was found that there are only small differences when luminance values estimated with auto-calibrated DSLR cameras are compared with those obtained for the commercially calibrated camera for low to mid-range luminance values (50 – 5000 cd/m 2 ). However, for higher luminance values (>5000 cd/m2 ), HDR images from the auto-calibrated camera show differences of up to 20 %, which could be problematic for glare investigations. More studies specifically focusing on high luminances are needed to determine more conclusively whether certain limitations should apply to the use of automatically calibrated DSLR cameras for glare evaluations.
Using Virtual Reality to investigate the experience of daylit spaces
7th VELUX Daylight Symposium, Berlin, Germany, May 3-4, 2017.
This poster introduces the methodology and main findings to date in Kynthia Chamilothori's PhD thesis, regarding the use of virtual reality as a substitute for experiments in the real space, and the investigation of how facade characteristics influence the perception of a daylit space.
Swiss school typologies from a daylighting perspective between 1945 and 2015
VELUX Daylight Academic Forum, Technische Universität Berlin, May 2017.
The research consists of three successive and interdependent parts. The 1st part seeks to reconstruct the typological evolution of primary schools and their associated daylighting strategies between 1945 and 2015 in Switzerland – a country widely recognized for its constructive quality and its concern for integration of natural light in schools – while demonstrating the significant impact of foreign influences on Swiss production. To do this, a large chronological and systematic census of schools is carried out in four major architectural journals: Werk, L’architecture d’Aujourd’hui, Techniques & Architecture and Architectural Review. The formal and constructive evolution of the projects is detailed and the daylighting mechanisms of the class units are identified, while looking at the impact of the evolution of child pedagogy on architecture. Then an identification and selection of school models, that are most representative of the typological evolution and the use of lighting throughout the different epochs, is carried out for the second part of the thesis. The 2nd part begins with the observation, that many recent research findings demonstrate the importance of a significant and controlled amount of natural light for reading and writing tasks and more generally, its role in the physical and psychic well-being of the students. Thus, it is now necessary for designers to reflect more and be aware of the use of ideal natural lighting strategies, no longer relying on electrical lighting – often permanently lit – to provide the necessary light levels, although electrical light is less comfortable for the human eye and synonymous with significant energy expenditure. The second part proposes to analyze the daylighting performance of the selected schools by using 3D simulation. This in order to quantify the different levels of illuminance and to study the resulting luminous atmospheres. Several observations and measurements are also carried out in situ following a precise protocol. The objective is to compare the principles and typological families of our initial theoretical census, by iteratively varying the different architectural elements constituting the units of modeled classrooms (geometry, openings, solar protections, types of glazing, etc.), while questioning the recommendations and regulations related to the daylighting of school buildings that are in force in Switzerland and abroad. Based on the results obtained, the 3rd part proposes to accurately identify criteria and architectural models that offers adapted and controlled levels of illuminance for students. The first aim is to reconstruct the evolution of 70 years of school construction in Switzerland, based on the original perspective of daylight integration principles. The second aim is to propose a library of examples of good architectural practices, while also objectively criticizing the daylighting strategies in Swiss schools – and of the literature that made it known – by comparing contemporary production and recommendations in terms of lighting with the constructions built from 1945, and which placed – at least for certain typologies – natural light in schools at the center of the projecting process. By combining the daylight performance of school spaces with a wider historical, spatial, and pedagogical approach, the objective is to positively influence decisions related to the design of naturally lit spaces in the school of tomorrow.
ACTIVE INTERFACES. From 3D geodata to BIPV yield estimation: towards an urban-scale simulation workflow
15. Nationale Photovoltaik-Tagung 2017, Lausanne, Switzerland, March 23-24, 2017.
In order to meet the requirements of the Energy Strategy 2050, there is the need for a large-scale energy retrofit of the current building stock combined with the use of solar active systems, in particular BIPV. However, existing tools to assess the potential solar energy yield, such as solar cadasters, present some limits. For instance, they calculate solar irradiation only on rooftops, neglecting hence the potential for façade-applied systems. Moreover, inter-reflections are usually not considered, although their contribution might be significant in dense urban areas. To overcome some of these limits, we present here a simulation-based workflow for the assessment of the BIPV potential in urban areas, applying advanced solar radiation and PV-modeling tools to detailed 3D city models. We use 3D geodata, including buildings with their actual roof shape and overhangs, terrain and vegetation, that are (or will be soon) available for all of Switzerland. In our workflow, all building surfaces are first regularly subdivided according to a given PV module size. For each sub-surface, the POA irradiance is then calculated using weather data from Metonorm and the software CitySim, whose radiation model includes direct, diffuse and reflected components. We finally apply the Sandia cell temperature model and the De Soto “Five Parameter” module model to calculate the DC power of the system. We here show the application of the workflow for some sample buildings in the city of Neuchâtel, while discussing its suitability for urban-scale assessments.
CONTRAST GLARE AND INTERPERSONAL VISUAL SYSTEM CHARACTERISTICS
6th VELUX Daylight Symposium, London, 2-3, 2015..
There are major uncertainties in the existing glare prediction models which makes them only partially capable of predicting user responses to visual environments. The models are particularly limited when predicting glare in spaces with large non-uniform glare sources; for example a daylit office (Fisekis et al., 2003; Bellia et al., 2008; Clear, 2013; Boyce and Smet, 2014). There are also large differences in the interpersonal perception of glare. Eye colour, age and gender have been investigated but have been shown to have little to no effect on glare perception. This could be an indication that another attribute has an impact on glare perception, such as contrast sensitivity or improperly corrected eyesight (Osterhaus and Bailey, 1992; Wienold, 2009)
Evaluating spatial ambiences through daylight variability, contrast and view
6th VELUX Daylight Symposium, London, September 2-3. 2015.
This research aims to give insight into the aesthetic aspect of the spatial and temporal diversity of light in space through experimental studies. By using empirical methods to establish a relationship of spatial contrast, daylight variability and view out with occupant preference and perception, we aim to link traditionally non-quantifiable aspects of daylight in space such as ambience with novel quantifiable metrics, validated in real space. The proposed project focuses on the development of reliable metrics to assess preference and perception related to daylight variability along with view out. Furthermore, this research will explore the influence of the perceptual effects of daylight such as daylight variability and contrast on the perceived spatial ambience. This study will be divided in two parts, namely the design and conduction of experiments in virtual space and the validation of the findings of the first study through real space experiments. We aim to represent and evaluate a wide range of daylight and view conditions, which can enable the emergence of patterns in the subject of preference and appraisal in the experience of architectural space.
Adaptive visual and thermal comfort
6th VELUX Daylight Symposium, London, September 2-3, 2015.
Increasing efforts are devoted to enhance and optimize the environmental comfort in buildings, as this aspect plays a major role in the affection of health, performance and general well-being of people. Indoor air quality, acoustic ambience, light and thermal conditions have been proved to be fundamental factors for the indoor environmental quality. Engineers must be aware of the effects of the interactions between these factors on the indoor comfort as people react simultaneously to diverse stimuli belonging to different sensorial fields and adapting their behaviors according to the associated conditions. Being able to know how these interactions influence the users’ comfort can lead to marked energy savings and positive influence on users’ productivity. Many studies have been conducted on the influence of each component on the overall comfort, but only few studies are available investigating the interaction between different comfort variables of different disciplines. This research focuses on the interaction between visual and thermal comfort for building users in school environments, looking at the impact of different perceptive conditions on the productivity of the users and overall comfort. In particular, it analyzes the effect of visual variables on the perceived thermal comfort and of thermal variables on the perceived visual comfort, beside the mutual interaction of visual and thermal variables on the overall comfort appraisal. The study is based on fundamental concepts belonging to different branches of knowledge, ranging from engineering to psychology and physiology for the considered purpose. These disciplines come together in search for objective interactions between different comforts by means of experiments in realistic climate chamber or controlled field studies. The goal of this study is to propose new guidelines for informing building designers on the interaction between visual and thermal variables and their influence on human comfort and productivity in the built environment. The results of this study will ultimately foster the development of control systems with the aim to achieve energy savings, increase user satisfaction as well as boost productivity.
Combining wearable eye-tracking with 4π light-field measurements: towards controlling all bottom-up and top-down factors driving overt attention during real-world tasks
10th Göttingen Meeting of the German Neuroscience Society, Göttingen, Germany, March 13-16, 2013.
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.
Understanding View Direction in Relation to Glare in Daylit Offices
VELUX Daylight symposium: New eyes on existing buildings, Copenhagen, May 14-16, 2013.
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.
Healthy lighting: integrating non-visual responses into simulation framework
5th VELUX Daylight Symposium, Copenhagen, Denmark, May 15-16, 2013.
Lighting is one of the most significant factors in the built environment that affect human health and wellbeing. In addition to stimulating visual responses, light induces a range of non-visual responses in humans including synchronizing circadian rhythms and directly alerting the brain. These effects are primarily mediated via a novel photoreceptor that contains the photopigment melanopsin. The spectral sensitivity of melanopsin is shifted towards the blue part of the spectrum compared to rod and cone photoreceptors used for vision. Therefore, making the most of the available daylight, which is naturally rich in the blue part of the spectrum, is a promising approach and might play a large role in lighting recommendations for health. Lighting simulation software tools are designed to predict and analyze the dynamically changing nature of functions that take place in architectural settings influenced by occupants’ behavior and the outside environment. Because non-visual responses adapt to changes in light intensity and spectral composition over much longer time periods than visual responses, they must be evaluated based on dynamic threshold values with regard to intensity, spectrum, duration, history and timing of light exposure. However, existing lighting design methods, used to assess visual performance and comfort, are based on static threshold values, and thus cannot be directly applied to evaluate non-visual responses. The goal of this thesis is to develop a computer-based lighting simulation framework able to predict direct non-visual responses to light and to validate novel guidelines that can inform designers about how lighting might affect human non- visual responses in the built environment. One of the main challenges to be addressed is the dynamic interaction between daylighting, occupants’ behavior and human non-visual responses to light.
Healthy lighting: integrating non-visual responses to light into building simulation
ENAC Research Day, EPFL, Lausanne, Switzerland, April 23, 2013.
The goal of this thesis is to develop a computer-based lighting simulation framework capable of predicting human non-visual responses to light and to validate novel guidelines that can inform designers about how lighting might affect human non-visual responses in the built environment. The framework consists of four steps, including a mathematical model that accounts for spectral and dynamic variations in light exposure. As a part of the framework, different light exposure patterns are generated to simulate the effects of occupants’ actions, movements, and activities. The results are interpreted based on pre-defined design goals. Light is one of the most significant factors that affect human health and wellbeing in the built environment. Since 2002, when the first reports on the discovery of a novel type of photoreceptor were published, a new field of study started to emerge at the intersection of photobiology and architecture. The novel photoreceptors are the primary mediators of non-visual responses to light in humans, including synchronizing circadian rhythms and directly alerting the brain. These new findings emanating from the photobiology field have sparked a growing interest in the role of lighting design on human health and wellbeing. The novel photoreceptors contain the photopigment meanopsin. Melanopsin is more sensitive to short- wavelength light, with a peak sensitivity that is blue-shifted (λmax ≅ 480 nm), relative to the photopic visual system (λmax ≅ 555 nm), which is dominated by the response of cone photoreceptors. In addition to the difference between the photoreceptors’ spectral sensitivity, researchers have identified intensity, duration/pattern, history, and timing of light exposure as important variables that control the non-visual light response in humans. Considering the blue-shifted sensitivity of the melanopsin-containing photoreceptors, the current recommendations for lighting, which are based mainly on visual criteria, may not provide the necessary amount of light to synchronize important physiological and behavioral rhythms to the 24-hour day. Moreover, a number of recent studies have demonstrated that exposure to bright light can improve alertness, performance, and mood. However, exposures to light at night can disturb circadian rhythms, such as hormone production and sleep-wake cycles, and have been linked to increased risk of cancer. Lighting simulation software tools are designed to evaluate visual requirements and comfort taking into account the stochastic fluctuations linked to the climate and to the behavior of the buildings’ occupants. The evaluation compares simulated light intensity values on a horizontal plane with static threshold values. Since the non-visual system responds slowly to light exposure and adapts to changes in light intensity and spectral composition over much longer time periods than the visual system, the lighting simulation software tools cannot be applied directly to evaluate the non-visual response to light. The response must be evaluated based on dynamic threshold values, which depend on intensity, spectrum, duration, history, and timing of light exposure. Currently, there is no mathematical model that incorporates all five variables to predict the non-visual effects of light on humans. Further, the movements of humans must be simulated to account for the amount of light received at the eye. Thus horizontal sensors on a plane must be replaced with vertical sensors at the eye level that can rotate and move around. The importance of building simulations is growing with increasing complexity of building design and higher performance requirements regarding sustainability. New methods, created at the interface between photobiology and architecture, predicting the non-visual response to light are needed to support design decisions.
Solar Potential and Interactive Design in the Urban Context
sb13 - Sustainable Buildings: Implementing Sustainability, Barriers and Chances, Munich, April 24-26, 2013.
This poster exposes the outline of the PhD research project of the main author (E. Nault), which focusses on improving the solar potential of neighborhoods at the early design phase and through an interactive design support methodology.
Nonvisual light-response model: a preliminary approach to integrating recent findings in biology into a lighting simulation process
Experiencing Light 2012 conference, Eindhoven, The Netherlands, November 12-13, 2012.
In addition to stimulating visual responses, light induces a range of circadian, neuroendocrine and neurobehavioral non-visual responses in humans. These effects are mediated primarily via a novel non-rod, non-cone photoreceptor, which is most sensitive to blue light (lambda_max 480nm) and exhibits different sensitivity to the spectrum, timing, intensity, duration and pattern of exposure as compared to visual responses. The discovery of this novel photoreceptor has led to consideration of the nonvisual effects of light as an important element of healthy lighting design in addition to vision. Before application of these new findings, however, it is necessary to first understand, and then model how the nonvisual system responds to light. One challenging aspect is the fact that the nonvisual system adapts its responses to changes in light intensity and spectral composition over a much longer timeframe than the visual system. Here, we propose a functional model of the nonvisual light-response relationship that combines temporal integration and a static nonlinear function.
Integrative approach to assess the performance of light-interacting façades and building materials
Saint-Gobain Daylighting Community Day, Aubervilliers, France, June 27, 2012.
Use of daylight offers great potential benefits in terms of energy savings, visual comfort and health, as long as it is properly controlled. This project is motivated by the necessity to describe façade systems and interior surfaces in order to quantify and compare their benefits in interaction with one another. It focuses on conventional and light-redirecting façade systems and their interaction with indoor coating material in terms of lighting potential. Comparisons are carried out using an annual climate-based performance metric for different façade systems. BTDFs of these façade systems are computed from a Radiance model. By linking incident light direction to transmitted light direction, they give a description of how light impinges on the coating. A Dynamic Radiance-based workflow is used to run a parametric study of relevant design factors such as transmission function, coating reflectivity and specularity.
IDEAS - Integrated Design, Architecture and Sustainability
ENAC Research Day, EPFL, Lausanne, Switzerland, June 15, 2012.
The axis "Integrated Design Architecture and Sustainability" (IDEAS) is a joint initiative of both the Interdisciplinary Laboratory of Performance-Integrated Design (LIPID) and Laboratory of Architecture and Sustainable Technologies (LAST) of the School of Architecture, Civil and Environmental Engineering (ENAC) at EPFL. It aims to address an increased integration of the various issues related to sustainable architecture within the framework of the Doctoral program Architecture & Science of the city (EDAR) as well as a desire to strengthen exchanges and synergies between the three institutes of ENAC. Towards this end, it lies on one hand on a new interdisciplinary education offer in the form of seminlasars and workshops, and on the other hand on a networking structure for EPFL PhD students.
Towards a model for View Direction patterns as a function of light distribution
ENAC Rresearch Day, Lausanne, Switzerland, June 8th, 2011.
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.
Simulation of the Non-Visual Effects of Daylight
CIBSE Technical Symposium, De Montfort University, Leicester, UK, September 6-7, 2011.
The daylight design of building spaces for non-visual effects could have major implications for healthcare and residential buildings where occupants can remain in fixed positions for extended periods. This poster describes the formulation and application of a simulation model to predict the cumulative magnitude of non-visual effects due to daylight in buildings.
Model for view direction as a function of light distribution
Academic Forum of the 4th Velux Daylight Symposium, Lausanne, Switzerland, 4-5 May 2011.
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.
Towards a refined understanding of comfort in workspaces
Swiss – Emirati Friendship Forum: UAE-Swiss Research Day 2011, Lausanne, Switzerland, 22 - 23 June 2011.
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.
NOMAD - Network of Optimization Modalities in Architectural Design
Swiss – Emirati Friendship Forum: UAE-Swiss Research Day 2011, Lausanne, Switzerland, 22 - 23 June 2011.
Two pairs of identical experimentation modules are being developed within the framework of a collaborative initiative named NOMAD – Network of Optimization Modalities in Architectural Design - between the Interdisciplinary Laboratory of Performance-Integrated Design (LIPID) and the Laboratory of Architecture and Sustainable Technologies (LAST), both at EPFL. NOMAD relates to a series of projects related to the optimization of the building envelope in a sustainability context. Based on comparative evaluations in two climates (cool-temperate versus hot-arid), these projects will most notably rely on a dual infrastructure: the NOMAD modules. These modules will be located in Lausanne, Switzerland and in the Middle East (Ras-Al-Kaimah, United Arab Emirates (U.A.E.). They are currently in design development and will be operational in the fall of 2012 for the launching of the Master in Energy Management and Sustainability Caravans. One pair of modules will be located on the main EPFL campus in Lausanne, Switzerland and the other pair will be installed on the site of the EPFL Middle East campus in Ras-Al-Kaimah, U.A.E. The modules’ dimensions will be 3 m wide x 3 m high x 9 m deep so as to allow deep plan layouts, and include an active insulation skin for temperature and heat exchange control. Having the modules in pairs offers the option either rely on a reliable reference case in any measurement campaign, to hide the measurement setup from the users in field studies, or to conduct two experiments simultaneously to get most out of periods where optimal climate conditions are scarce. This dual climate approach allows us to open up an innovative and original research framework, able to generate new façade concepts with high environmental standards, and to develop bio-climatic strategies based on multiple criteria. This unique dual research facility will thus be particularly adapted to investigate climate-related issues in building technology and to enhance the educational potential in sustainable architecture at EPFL and EPFL Middle East.
Increasing Useful Daylight – Promising Systems and Technological Challenges
3M Science and Engineering Faculty Day, St-Paul/Minneapolis MN, USA, June 16 - 17, 2009.
While there is no doubt daylighting can offer great benefits in terms of energy consumption, sustainability and health, it is also highly sensitive to a careful planning and control. Not only must we try to increase the availability and use of daylight inside buildings, we must also ensure its quality and therefore its energy-efficient and user-responsive control. Any daylighting strategy has to be approached from an integrated perspective, encompassing its potential for illumination, heating and pleasantness and considering its liabilities in terms of glare, thermal discomfort, extra cooling needs and variability. This requires a careful planning based on accurate predictions, for which detailed transmission and reflection data of the fenestration components are essential.