Juliette van Duijnhoven

• Assistant Professor in Building Lighting
• Assistant Professor at Eindhoven University of Technology

Wearable light loggers are becoming increasingly available for various applications. This study employed a survey design to systematically analyze wearable light loggers, focusing on their key characteristics and usability. A comprehensive survey instrument was developed through expert meetings and iterative discussions, encompassing categories suc...

Daytime light levels are important for human physiology. Office workers spend most of their daytime inside buildings where it is unclear whether they receive healthy light levels. A recent publication presented recommendations for the minimum daytime light level for optimal human health, expressed in melanopic equivalent daylight illuminance (EDI)....

Light fulfils numerous roles in human lives resulting in different lighting needs presented in standards and guidelines. For any lighting design, lighting measurements are crucial for evaluating the installed lighting system. Calibrated photometers are recommended for accurate measurements, although smartphones are sometimes used for indicative mea...

In recent years, a shift towards working from home has taken place. For conventional offices in Europe, the lighting is designed complying to standards such as the EN 12464-1 and the EN 17037, and recommendations regarding non-image forming effects are available. However, for the home office, the aforementioned standards do not yet exist, although...

Light exposure is an essential driver of health and well-being, and individual behaviours during rest and activity modulate physiologically relevant aspects of light exposure. Further understanding the behaviours that influence individual photic exposure patterns may provide insight into the volitional contributions to the physiological effects of...

Light exposure is an essential driver of health and well-being, and individual behaviours during rest and activity modulate physiologically-relevant aspects of light exposure. Further understanding the behaviours that influence individual photic exposure patterns may provide insight into the volitional contributions to the physiological effects of...

Light affects many aspects of human physiology, through the non-image-forming (NIF) pathway. To account for this pathway, lighting design simulation tools need to combine several luminous and temporal factors to predict how architectural and lighting design decisions affect eye-level light exposure. Based on a systematic literature review, containi...

The ipRGCs in the human eye mediate several effects on people, such as alertness and circadian rhythms. The spectral, temporal and spatial characteristics of light influence the magnitude of these effects. To facilitate the anticipation of the ipRGC-influenced light (IIL) responses in building design, new simulation tools are needed. This paper pre...

This paper presents findings of an online survey on the design practice of lighting professionals and their knowledge about non-visual effects of light. The results showed that there is basic awareness among lighting professionals about the effects of light beyond vision, although discrepancies were noticed. Two thirds of the respondents stated tha...

Light exposure is an important driver of health and well-being. Many aspects of light exposure are modulated by our behaviour. How these light-related behaviours can be shaped to optimise personal light exposure is currently unknown. Here, we present a novel, self-reported and psychometrically validated instrument to capture light exposure-related...

Background: Light exposure is essential for our health and well-being, driving various non-visual processes, including circadian photoentrainment, melatonin suppression and the modulation of alertness. An unexplored dimension of light exposure is that it is partially controlled by our behaviour. Here, we present a novel instrument to capture light...

Light via our eyes influences visual performance, visual comfort and visual experience, but also affects several health related, non-image-forming (NIF) responses. New metrics have been developed to quantify the NIF effects of light. In order to incorporate these in lighting design practice, simulation tools are required that are able to process in...

The discovery of the ipRGCs was thought to fully explain the mechanism behind the relationship between light and effects beyond vision such as alertness. However, this relationship turned out to be more complicated. The current paper describes, by using personal lighting conditions in a field study, further exploration of the relationship between l...

Light enables us to see and perceive our environment but it also initiates effects beyond vision, such as alertness. Literature describes that at least six factors are relevant for initiating effects beyond vision. The exact relationship between these factors and alertness is not yet fully understood. In the current field study, personal lighting c...

The main reason lighting control is being applied is to reduce energy consumption. However, there are many more reasons for lighting control to be optimised in buildings. Lighting systems can be controlled to enhance or optimise effects beyond vision. Automatic control of electric lighting systems or daylight systems is one way of adjusting someone...

Background: Light and alertness studies have applied different measurement methodologies to determine lighting conditions. However, it has been demonstrated that researchers rarely measure or describe the lighting conditions of their studies in sufficient detail to generalize conclusions or derive universal guidelines. Objective: Part I of this...

Lighting controls in offices are still mainly focused on energy savings. However, focusing on a potential productivity increase of office workers would lead to much higher savings in company costs. A less alert office worker performs a task worse compared to a more alert office worker. This project aimed at developing input for intelligent systems...

Light is one of the important aspects for a comfortable office environment. Too often high quality lighting is not achieved. Lighting quality can be defined by different aspects that are relevant such as the quantity, distribution, glare, spectral power distribution, daylight, directionality, and dynamics of light. The luminance distribution seems...

Research demonstrated a large variety regarding effects of light (e.g. health, performance, or comfort effects). Since human health is related to each individual separately, the lighting conditions around these individuals should be analysed individually as well. This paper provides, based on a literature study, an overview identifying the currentl...

The current field study investigated the ambiguities regarding the relationship between office lighting and subjective alertness. In laboratory studies, light-induced effects were demonstrated. Field studies are essential to prove the validity of these results and the potential recommendations for lighting in future buildings. Therefore, lighting m...

Sports facilities all over the world apply LED lighting. The combination of high luminance and small luminous surfaces causes a high probability of glare and LED lighting contains these specifications. There are specific situations for which validated glare models exist, such as offices or outdoor soccer fields, although indoor sports facilities ar...

Health symptoms may be influenced, supported, or even controlled via a lighting control system which includes personal lighting conditions and personal factors (health characteristics). In order to be effective, this lighting control system requires both continuous information on the lighting and health conditions at the individual level. A new pra...

Purpose The International Commission on Illumination (CIE) recommends researchers to investigate a wide variety of behavioural and health outcomes. However, researchers often investigate only a part of occupational health (OH) in relation to light. A literature study (2002–2017) regarding the relationship between office lighting conditions and OH w...

Light beneficially influences human health directly, but moreover, indirectly via occupant's satisfaction with lighting. This study identified parameters influencing occupant's satisfaction with lighting. During a five-day study, 46 office workers evaluated their office lighting conditions once a day using the Office Lighting Survey. The significan...

The benefits of light in offices beyond enabling visual tasks have been demonstrated in former studies. Light positively influences outcome measures such as human's health, wellbeing, visual comfort, motivation, and environmental satisfaction. In order to measure the effects of light on the individual outcome measures, it is of high importance to c...

Occupancy-based lighting control can be applied at several resolution levels. To aid lighting designers in choosing the appropriate solution for a specific open-plan office case, this paper presents a simulation tool which enables calculating the lighting energy use for the different control strategies. By using a stochastic modelling approach and...

When determining the effects of light on human beings, it is essential to correctly measure the effects, and to correctly measure the adequate properties of light. Therefore, it is important to know what is being measured and know the quality of the measurement devices. This paper describes simple methods for identifying three quality indices; the...

Background: The non-image-forming effects of luminous radiation on people with intellectual disabilities or dementia received attention from researchers. Such studies, however, have generally been conducted using disparate methodologies which precludes generalization and reproducibility. Objective: The aim of this study was to determine the prac...

(Day)light in office buildings has already been proven to be a beneficial contributor to health. However, people’s perception of the physical light environment deviates significantly from objective measurements. Large differences between user’s perception and objective light parameters, such as illuminance level or daylight contribution, could lead...

Workplaces are transforming from office rooms to office landscapes. Previous research about indoor environmental (IE) aspects and health, investigated work-related health issues mostly in conventional office spaces. It is still uncertain which physical aspects in office landscapes might influence employees’ health the most. An exploratory study, in...