On the Impact of Integration of Non-Image Forming (NIF) Effect of Light on Electrical Lighting Control in Non-Residential Buildings

Marta Benedetti, Ali Motamed, Jean-Louis Scartezzini
2016
Article de conférence

Résumé

Lighting has an impact on the visual as well as cognitive performance of people in non-residential buildings. Light is the most powerful time cue for resetting the circadian pacemaker and ensuring correct synchronization of the internal clock with the environment: these effects are called “Non-Image Forming” (NIF) functions. The expected neuroendocrine and neurobehavioral responses of subjects to light exposure can be summarized in four principal categories: alertness, sleep quality, mood and performance. The properties of light such as intensity, timing, pattern and light history influences neurobehavioral responses. These significant effects of light are currently not considered in building automation mainly due to the unknown and complicated nature of NIF effects as well as lack of proper technology. This leads likely to a considerable loss of productive time and momentum for the office occupants. This paper explores the existing knowledge of NIF effects of light on human beings and consequently proposes a novel dynamic lighting pattern, which is used as a set point for an integrated daylighting and electric lighting system. In other words, the existing scientific knowledge of NIF effect of light is introduced into the lighting engineering and automation domain. This user-centric approach allows for a system level study of the suggested variable lighting set points. A novel High Dynamic Range (HDR) vision sensor installed next to the office user allows for an ‘on-the-fly’ evaluation of the light flux received by the human eyes during daytime: it also offers a personalized, refined control of an integrated electric lighting and sun shading system.

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https://infoscience.epfl.ch/record/222924?ln=fr

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Marta Benedetti, Ali Motamed, Jean-Louis Scartezzini
2016
Article de conférence

Résumé

Official source

https://infoscience.epfl.ch/record/222924?ln=fr

À propos de ce résultat

Concepts associés (10)

Léclairage est l'ensemble des moyens qui permettent à l'homme de doter son environnement des conditions de luminosité qu'il estime nécessaires à son activité ou son agrément. L'éclairage associe u

Daylighting is the practice of placing windows, skylights, other openings, and reflective surfaces so that direct or indirect sunlight can provide effective internal lighting. Particular attention i

vignette|Rayons de lumière sortant des nuages. Dans son sens le plus habituel, la lumière est le phénomène à l'origine d'une sensation visuelle. La physique montre qu'il s'agit d'ondes électromagnétiq

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Integrated Daylighting and Artificial Lighting Control based on High Dynamic Range Vision Sensors

Ali Motamed

One fifth of the electricity consumption of Swiss buildings is due to electric lighting. Integrated control of sun shading and artificial lighting can mitigate this demand while maintaining user comfort. However, the drawback of existing building control approaches is that they do not consider one of the main aspects of human-centric lighting: visual comfort. The goal of this doctoral thesis is to develop an integrated energy efficient sun shading and electric lighting control system that incorporates widely accepted visual comfort criteria and privileges daylighting over electric lighting. The first part is dedicated to High Dynamic Range (HDR) vision sensor calibration, programing, validation and preliminary testing. A sensor originally developed by the Centre Suisse dâElectronique et de Microtechnique (CSEM) was photometrically, spectrally and geometrically calibrated and validated with respect to reliable illuminance and multi-point luminance meters. This HDR vision sensor was then equipped with an embedded image processing routine in order to assess âon the flyâ discomfort glare indices. It has been demonstrated that the developed device, is able to serve as an enhanced visual comfort feedback sensor in building automation systems. On the other hand, it can be employed to characterize highly glazed facades and workspaces regarding visual comfort and glare risks, as demonstrated in a project in Singapore. Two monitoring campaigns are reported in the second part of this thesis. Firstly, 30 human subjects occupied two identical office rooms of the LESO solar experimental building for 15 afternoons to compare the performance of a fuzzy logic control system incorporating two HDR vision sensors with respect to a âbest-practiceâ controller. Subjective self-reported visual comfort surveys, paper- and computer-based visual tests and monitoring of the electric lighting consumption were carried out simultaneously in both offices. It was shown that the electricity demand of the office with the advanced controller is 32% lower than that of the reference room, while the subjectsâ visual performance remained comparable. Secondly, an eight-month data monitoring campaign was carried out in the same building in order to study the ability of a novel control approach to maintain optimal visual and thermal comfort conditions while reducing the energy performance gap of a room as well as its electric lighting demand. The experimental results showed that the advanced controller mitigated the performance gap during the heating season by 72% with regard to standard occupant behavior and by 19% with respect to a best-practice automated system. This system reduced backup heating demand leading to lower CO2 gas emissions. At the same time, visual comfort constraints regarding Daylight Glare Probability (DGP) and workplane horizontal illuminance were respected during work hours. Finally, a self-commissioning integrated controller for Venetian blinds enhanced with a learning module was developed and validated for 22 days in a daylighting testbed at the Fraunhofer Institute for Solar Energy (ISE) in Freiburg, Germany. It has been shown that the visual comfort constraints are respected for 96% of the work hours and that the controller can successfully limit the number of shading movements. The market potential for HDR vision sensors and integrated control platforms has been studied and possible commercialization tracks have been identified.

EPFL2017

Chargement

Sufficient daylight exposure contributes to occupants' productivity and health in buildings. However, excessive daylight ingress induces discomfort glare and increases the cooling load in warm seasons. The performance of manual shading systems is limited by usersâ low interaction frequency. Since sky conditions are dynamic, frequent adjustments are necessary, but these are impractical for users to manage. Various shading automation systems have been proposed to better exploit daylight in buildings, the performance of which is limited by a number of factors, including insufficient glare protection, disturbing movement of slats, privacy issues, and commissioning difficulty. In this thesis, an integrated daylighting control system is proposed and demonstrated to regulate daylight in buildings based on real-time lighting computing with the monitored luminance distribution of the sky and landscape, as a decentralized system. First, an embedded photometric device (EPD) was designed and validated for improved accuracy in daylighting simulation compared to standard sky models. The EPD is composed of an imaging system and a microprocessor. After calibration, the spectral response of the imaging system is close to the photopic luminosity function, achieving a 8.9% spectral correction error. The luminance detection range spans 1.2x10^2 ~ 3.78x10^9 cd/m^2, covering extremes of both the shadowing landscape and the sun orb luminance. The EPD monitors the luminance distribution of the sky vault and the ground. Based on the generated luminance map, the EPD is able to perform on-board lighting computing. The performance of work-plane illuminance (WPI) simulation was cross validated with a lux-meter array in a daylighting test module under different sky conditions achieving a mismatch of below 10%. Secondly, since the bidirectional distribution function (BTDF) commonly used in lighting simulation involves bulky data, a compression scheme based on planar wavelet transform was investigated and generic error and the influence on daylighting simulation were also studied at various compression ratios. Results showed that both WPI and daylight glare probability (DGP) are relatively immune to a BTDF compression ratio below 100. Thirdly, an automated Venetian blind was designed which integrates the EPD as both a sensing unit and a controller based on real-time lighting simulation. The EPD determines an optimal shading position according to the simulation results, to offer sufficient WPI, mitigate excessive solar heat gain (SHG), temper discomfort glare, and maximize outwards view. 'In-situ' experiments demonstrated that the automated Venetian blinds were able to regulate WPI efficiently. The expected SHG saving was estimated to reach 47% in warm seasons. It was also demonstrated to mitigate discomfort glare timely, including veil glare from surroundings. A subjective study conducted with 34 subjects showed satisfaction with regulated daylight provision, glare mitigation, and quietness of slat movement. Finally, the EPD was applied to control tint states of a split-pane electrochromic (EC) window to secure occupants' visual satisfaction. Experimental results in a full-scale testbed showed that the WPI was within the confined range with regulated daylighting under clear skies 83% of time and the DGP 95% of the time; under partly cloudy skies, the WPI was within the range 62%~68.2% of the time and for the DGP 85%~94% of the time to achieve visual comfort

EPFL2019

Chargement

Impact of dynamic lighting control on light exposure, visual comfort and alertness in office users

Marta Benedetti, Lenka Maierova, Ali Motamed, Mirjam Münch, Jean-Louis Scartezzini

The lighting environment at indoor workplaces is important not only to provide vision and visual comfort, but also for light's direct influence on human physiology, cognitive performance and mood. The purpose of this ongoing study is to investigate the impact of a dynamic control of combined daylight and artificial lighting on office users' visual comfort as well as on alertness and cognitive performance. We are going to evaluate the impact of two different office lighting conditions in a quasi-real setting on subjective alertness ratings in healthy young participants over several days. We will compare an office with optimized daylighting and artificial lighting, operated by a new control system with a standard office room, where the lighting/shading can be changed manually. The aim of this balanced crossover within study design is to show that exposure to optimized dynamic lighting control over several days is superior on subjective alertness and glare indexes, when compared to a conventional lighting control. Here, we present some preliminary results from the first six participants on the comparison of subjective evaluations of alertness and the objective monitored (day-) light exposures and glare index Daylight Glare Probability (DGP) in the two different conditions over one week (five days) each.

IOP Science2019

Chargement

Integrated Daylighting and Artificial Lighting Control based on High Dynamic Range Vision Sensors

Ali Motamed

EPFL2017

EPFL2019