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Project 24 is an urban art project in the underpass (M1 metro) in the north district of EPFL. This underpass is a key way for access to the EPFL campus, and to reach the new northern district and the SwissTech Convention Center. The project is focused on the design of the lighting concept of the renovated underpass, taking into consideration aesthetics, colour and energy concepts.

The use of natural light in buildings can affect our physiological and psychological health and has comfort, behavioral, economic, and environmental consequences.

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)

Due to climate change, the built environment is facing increasingly strict environmental targets. Thus, architects are challenged to design evermore high-performing buildings, a task for which they can no longer depend solely on their experience and intuition. Building performance simulation (BPS) tools have become central in this context to support the design process. Yet, several studies show that such tools are still not widespread among practitioners at early design stages. Despite significant efforts made to deliver more “architect-friendly” tools, a gap remains between the expected use and the reality, highlighting the need to adapt the design-approach when developing such tools. A usercentred design approach seems promising for increasing the usability and acceptance of BPS tools, and should be fine-tuned through multiple iterations between BPS developers and potential users via usability assessments. However, as usability assessment has its origins in the domain of human-machine interaction, no methodology has been proposed yet specifically for BPS tools. This paper is the result of a first interdisciplinary pilot study, describing and evaluating a usability assessment method for a new BPS tool that supports the low carbon building design process. Usability, the reliability of the tool and its usefulness are amongst the dimensions that have been assessed with a selected population of future users. Moreover, recommendations and guidelines for the reproducibility of the test are provided. The study shows that both, the quantitative and qualitative results gathered through a usability assessment are insightful to develop a BPS tool that is efficient, satisfactory, pleasant to use and widely adopted by designers.

To assess the daylighting performances of a building, one of the most commonly used quantities is the Daylight factor, which is defined for a given surface element inside the analysed room as the ratio of the inside and outside illuminances under a CIE overcast sky. The Daylight factor consists of three components: the sky component, due to light flux reaching the surface element directly from the sky, the externally and the internally reflected components, respectively due to light flux reflected on external and internal surfaces. To estimate the direct sky component (also called sky factor), analytical methods can be used, based on the luminance distribution of the sky and the window’s geometric properties (dimensions and position in regard to the considered surface element). However, such methods have always been restricted to vertical (lateral) and horizontal (zenithal) windows, requiring heavy approximations to be applied whenever a tilted rectangular opening was considered. In this paper, a generalized method for assessing the sky component is proposed, extending it to rectangular windows of any tilt angle. As a purely analytical approach was found to be inapplicable, it is based on an optimised combination of vertical and horizontal windows situations. To validate the developed methodology, scale model measurements were performed with a sky simulator for two rectangular openings of varying tilt angle (every 15° from vertical to horizontal): the experimental results proved to be in very good agreement with the calculation-based approach.

A daylighting system for use in a building including a louver array having a first longitudinal element, and a second longitudinal element spaced therefrom. At least one of the first and second elements has an asymmetrical profile, each of the first and second longitudinal elements has a bottom profile including a parabolic surface, portions of opposing surfaces of the first and second longitudinal elements define a compound parabolic concentrator profile, a center line of the compound parabolic concentrator profile is non-horizontal and is tilted upwards, and the array prevents line of sight therethrough. A louver for a daylighting system includes (i) a leading edge defined by an intersection of a parabolic concentrator surface, and a flat surface; and (ii) a trailing edge defined by an intersection of a lower compound parabolic concentrator profile, and an upper compound parabolic concentrator profile. A method for designing a louver profile is provided.

Digital video-based luminance mapping systems require the establishment of a precise relation between the considered spatial referential and the associated pixel coordinates on the image. Such a relation may vary with the measurement conditions, and an adjustment of the geometric calibration therefore becomes necessary. In this paper, a methodology for adapting the image calibration according to the referential transformations is proposed, based on the use of a set of matrices individually associated to each spatial coordinate. These matrices are modified with analytical conversions in order to define the actual measurement situation. The description of this approach is given through an application example on a recent bidirectional goniophotometric device, based on digital imaging, proving the consistency of the adopted methodology.

Advanced daylighting systems can be effective in increasing light levels in building spaces and reducing energy consumption due to electric lighting. However, a recurring issue found in most existing daylighting systems is the necessity of coupling the light-redirecting technology with a separate light shade to reduce glare risks. A different approach is proposed here, based on the use of a louver system which scatters incoming light onto a reflective ceiling, where it is redirected deep into the space. This type of system is effective for both diffuse daylight and direct sunlight without causing glare and without the need for a shading system. Annual simulations of workplane illuminance were conducted with Radiance using Tokyo weather data and a generic south-facing deep-plan office space. Glare was evaluated through testing of a physical prototype of the system. The new system was compared to a base case consisting of an unshaded window of equal area to the louver system. The results show that the novel louver system enables a significant decrease in electric lighting usage and outperforms the uncovered window, while adequately controlling direct sunlight to prevent glare.

Office employees are exposed to a variety of environmental and contextual stimuli that might drive them to perform control actions, such as operating windows or window blinds. These actions have a significant impact on building energy use and increase uncertainty when predicting building performance. Despite the advancements in the understanding of separate fields of comfort (thermal, olfactory, visual, and acoustic), the combined effect of Indoor Environmental Quality (IEQ) factors on user perception and behaviour in real buildings merits further explorations. In this context, the eCOMBINE framework ("Interaction between energy use, COMfort, Behaviour and the INdoor Environment in office buildings") aims to create new knowledge on human-building interactions in office environments, with a dedicated focus on open plan offices. This paper provides initial results of the eCOMBINE monitoring campaign performed during a two-week period in winter (February 2020) in Switzerland. The main subjective drivers behind interactions with windows and window blinds were analysed based on self-reported actions collected with a dedicated mobile application called OBdrive, which was installed close to windows and window blinds to capture employees' motivations in real-time. The subjective feedback was supplemented with environmental data, such as operative temperature, air quality, lighting levels, and sound pressure levels. Environmental and subjective data were evaluated jointly to gain insights into the relationship between global environmental stimuli and human-building interactions. The results showed discrepancies between perceived air quality and motivation to open windows, which confirms that occupants might not always correctly interpret actual air quality. While the primary motivations for windows and blind control actions were rather logical (e.g., opening windows when it is too warm, closing blinds in case of glare), occupants' actions were often triggered by multiple motivations at a time, suggesting that a single criterion is not necessarily enough to capture occupant's action.

Our exposure to light has a key role in regulating our biological clock through a dedicated photoreceptor present in the human eye. Increased awareness to its criticality when it comes to human well-being is urgently needed, as this criticality is potentially greatest in dense urban environments, though it effectively applies to any inhabitable area in the world.

The UE M course aims to improve the students’ ability to see, to plan and to design light in architecture. The purpose is to consider light as a resource, a raw material, and to understand how it can be used to emphasize architectural concepts. The students were asked to adopt a sustainable approach focusing on comfort and energy concerns. The following topics were adressed : daylighting optimization, artificial lighting, design and testing of specific day- and electric lighting systems.

Invited keynote speaker

Despite the abundance of daylighting design software, there are few tools which focus on annually comprehensive and climate-realistic data, and fewer which give performance as a function of time. Lightsolve, a tool under development, emphasizes the importance of full year, climate specific data in early stage daylight design. It performs a representative group of annual simulations based on TMY2 data and graphically displays the results using both temporal maps and spatial renderings. With any new method, it is critical to determine if the intended audience finds it more useful than existing methods. Therefore, two user surveys were given. The first was given to practitioners and students attending a daylighting design workshop at MIT in January of 2009. Participants were taught to use both Lightsolve and Ecotect (with exports to Radiance and Daysim). The aim of this survey was to help validate the usefulness of Lightsolve’s temporal approach and the intuitive nature of the temporal maps, and to observe architects’ interaction with the software. Because of the limited number of responses, a different stand-alone survey comparing spatial and temporal daylighting data was given, mostly to student architects, in May of 2009. The aim was to judge how intuitive temporal data was to the inexperienced architect. This paper presents the findings of both surveys.

This paper will present an annual simulation-based workflow for assessing human perceptual and non-visual responses to daylight across a series of view positions in an architectural case study. Through the integration of mathematical models used to predict visual interest and non-visual health potential, this paper will introduce an automated workflow to assess an array of view positions (located at eye level) under varied sky conditions and across multiple view directions to analyze the predicted impacts of daylight on perception and health in architecture. This approach allows for a spatial and occupant centric analysis of daylight using an integrated simulation-based approach.