A.L.P. Rosemann

Systematic review on the interaction between office light conditions and occupational health: Elucidating gaps and methodological issues:

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 was performed to identify gaps and methodological issues. Method The OH outcomes investigated in this paper were grouped according to the International Classification of Diseases and analysed per category: physical and physiological health, mental health, eye health, sleep parameters and visual comfort. Results Findings from the literature study (20 eligible papers) showed that all OH aspects were mostly but not exclusively measured subjectively. Furthermore, most studies investigated only a fraction of office lighting parameters and OH aspects. Conclusions It seems that Correlated Colour Temperature (CCT) and illuminance mainly correlate with OH. However, this may also be explained by gaps and methodological issues in studies described in eligible papers. Based on the literature study, an overview was composed elucidating gaps and methodological issues of office lighting and OH studies. It can be used to design and target the purpose of light and health research.

Measured Efficiency of a Luminescent Solar Concentrator PV Module Called Leaf Roof

A functional prototype of a luminescent solar concentrator photovoltaic (LSC PV) module, called Leaf Roof, aims at demonstrating the design features of LSC PV technologies such as coloring, transparency, and flexibility in physical shape. In this paper, the prototype is presented and the first measurements of its performance are shown. The geometrical gain of this new type of PV module is 3.6. For two types of Leaf Roof modules, I– V curves have been measured resulting in efficiencies of 5.8% for a red-colored PV module, and 5.5% for a green-colored PV module under similar conditions. These results demonstrate colorful, robust solar energy collectors which can be produced in a wide variety of shapes are viable, attractive devices for use in building integrated systems. Additionally, thanks to the use of poly(methyl methacrylate) (PMMA) as a cell encapsulant, the Leaf Roof modules are less susceptible to energy losses at elevated temperatures due to high irradiance and high ambient temperature conditions.

Dimming strategies for open office lighting: User experience and acceptance:

Sensor-triggered control strategies can limit the energy consumption of lighting by considering the presence of users in the office and dimming lighting down when it is not needed. In multi-user offices, the application of occupancy-based dimming at room level limits the energy saving potential. However, zone- or desk-based dimming may affect the comfort of co-workers due to its dynamics. This paper reports the assessment by 17 participants (30–50 years of age) of occupancy-based dimming in a mock-up office, using different dimming speeds. Participants consisted of co-workers experiencing changes triggered by others, and actors triggering these light changes. While the participants performed an office-based task, the luminaire above the actors’ desk was dimmed from approximately 550 lx to 350 lx (average horizontal illuminance), and vice versa. The participants evaluated the dimming conditions regarding their noticeability and acceptability. The study showed that the noticeability of light changes due to dimming, increases when fading times become shorter. Dimming with a fading time of at least two seconds was experienced as acceptable by more than 70% of the participants. The results of this experiment provide insights to system behaviour that does not compromise user experience while addressing energy efficient use of electric lighting.

Personal Lighting Conditions to Obtain More Evidence in Light Effect Studies

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 currently used methodologies for measuring lighting conditions in light effect studies. 22 eligible articles were analysed and this resulted in two overview tables regarding the light measurement methodologies. In 70% of the papers, no measurement details were reported. In addition, light measurements were often averaged over time (in 84% of the papers) or location level (in 32% of the papers) whereas it is recommended to use continuous personal lighting conditions when light effects are being investigated. Conclusions drawn in light effect studies based on personal lighting conditions may be more trusting and valuable to be used as input for an effect-driven lighting control system.

Improving Lighting Quality by Practical Measurements of the Luminance Distribution

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.

Local Lighting Control in Open-Plan Offices: The Influence of Office Lay-Out

Highly granular lighting control involves switching on and off luminaires based on individual occupancy. The resulting high frequency of lighting changes can distract the office workers and negatively impact their work performance. In a cubicle office, this might be less of an issue than in an office without partitions, as users do not have an overview over the space here. We tested this control strategy in both office types and compared the results to determine the influence of office lay-out on the amount and acceptability of distractions that it poses. Our results indicated the opposite: occupants in the cubicle office were more often distracted and rated the distractions as less acceptable than in the bullpen office. As the job function types varied and the bullpen was consequently more dynamic, it seems that the type of work environment is of larger influence on users’ satisfaction with local lighting control. However, more research is required to confirm this finding.

An unobtrusive practical method to derive individual's lighting conditions in office environments

The benefits of light in offices beyond enabling visual tasks have been demonstrated in former studies. Light positively influences outcome measures such as humans 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 correctly measure lighting conditions in realistic environments per individual. This paper describes a six-step practical method to derive lighting conditions for all work places in an office building based on continuous reference measurements. The method proposed in this paper allows the shift from laboratory studies to field studies so that the real effect of office lighting can be investigated simultaneously while the office worker is doing his or her real work.