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 conditions of 62 Dutch office workers (aged 49.7 ± 11.4 years) were continuously measured and simultaneously self-reported activities and locations during the day were gathered via diaries. Each office worker participated 10 working days in spring 2017. Personal lighting conditions were interpreted based on four of the six factors (light quantity, spectrum, timing, and duration of light exposure). Large individual differences were found for the daily luminous exposures, illuminances, correlated colour temperatures, and irradiances measured with the blue sensor area of the dosimeter. The average illuminance (over all participants and all days) over the course of the day peaked three times. The analysis of the duration of light exposure demonstrated that the participants were on average only exposed to an illuminance above 1000 lx for 72 minutes per day. The interpretation of personal lighting conditions based on the four factors provides essential information since all of these factors may be relevant for initiating effects beyond vision. The findings in the current paper give first in-depth insight in the possibilities to interpret personal lighting conditions of office workers.
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Journal of Physics: Conference Series Paper • The following article is Open access Exploring the relationship between light and subjective alertness using personal lighting conditions J. van Duijnhoven1, M.P.J. Aarts1, E.R. van den Heuvel2 and H.S.M. Kort3,4 Published under licence by IOP Publishing Ltd Journal of Physics: Conference Series, Volume 2042, CISBAT 2021 Carbon-neutral cities - energy efficiency and renewables in the digital era 8-10 September 2021, EPFL Lausanne, Switzerland Citation J. van Duijnhoven et al 2021 J. Phys.: Conf. Ser. 2042 012119 Download Article PDF References Download PDF 29 Total downloads Turn on MathJax Share this article Share this content via email Share on Facebook (opens new window) Share on Twitter (opens new window) Share on Mendeley (opens new window) Hide article information Author e-mails j.v.duijnhoven1@tue.nl Author affiliations 1 Building Lighting Group, Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands 2 Stochastics, Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven, The Netherlands 3 Research Centre Healthy and Sustainable Living, University of Applied Sciences Utrecht, Utrecht, The Netherlands 4 Building Healthy Environments for Future Users Group, Department of the Built Environment, Eindhoven University of Technology, Eindhoven, The Netherlands DOI https://doi.org/10.1088/1742-6596/2042/1/012119 Buy this article in print Journal RSS Sign up for new issue notifications Create citation alert Abstract 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 light and subjective alertness during daytime. Findings show that this relationship is highly dependent on the individual. Although nearly all dose-response curves between personal lighting conditions and subjective alertness determined in this study turned out to be not significant, the results may be of high importance in the exploration of the exact relationship.
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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.
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TU Delft, in collaboration with Gravity Energy BV, has conducted a feasibility study on harvesting electric energy from wind and vibrations using a wobbling triboelectric nanogenerator (WTENG). Unlike conventional wind turbines, the WTENG converts wind/vibration energy into contact-separation events through a wobbling structure and unbalanced mass. Initial experimental findings demonstrated a peak power density of 1.6 W/m² under optimal conditions. Additionally, the harvester successfully charged a 3.7V lithium-ion battery with over 4.5 μA, illustrated in a self-powered light mast as a practical demonstration in collaboration with TimberLAB. This project aims to advance this research by developing a functioning prototype for public spaces, particularly lanterns, in partnership with TimberLAB and Gravity Energy. The study will explore the potential of triboelectric nanogenerators (TENG) and piezoelectric materials to optimize energy harvesting efficiency and power output. Specifically, the project will focus on improving the WTENG's output power for practical applications by optimizing parameters such as electrode dimensions and contact-separation quality. It will also explore cost-effective, commercially available materials and best fabrication/assembly strategies to simplify scalability for different length scales and power outputs. The research will proceed with the following steps: Design and Prototype Development: Create a prototype WTENG to evaluate energy harvesting efficiency and the quantity of energy harvested. A hybrid of TENG and piezoelectric materials will be designed and assessed. Optimization: Refine the system's design by considering the scaling effect and combinations of TENG-piezoelectric materials, focusing on maximizing energy efficiency (power output). This includes exploring size effects and optimal dimensions. Real-World Application Demonstration: Assess the optimized system's potential to power lanterns in close collaboration with TimberLAB, DVC Groep BV and Gravity Energy. Identify key parameters affecting the efficiency of WTENG technology and propose a roadmap for its exploitation in other applications such as public space lighting and charging.
The project focuses on sustainable travel attitude and behaviour with attention to balance, liveability, impact and climate change (as indicated above). The customer journey is approached from the consumer side and intends to shed light on the way COVID-19 has influenced (or not) the following aspects:• consumer’s understanding and appreciation of sustainability • the extent to which this understanding has influenced their attitude towards sustainable travel choices• the extent to which this change is represented in their actual and projected travel behaviour throughout the travel decision-making process • conditions that may foster a more sustainable travel behaviourThe project can be seen as a follow up to existing studies on travel intention during and post COVID-19, such as ETC’s publication on Monitoring sentiment for domestic and Intra-European travel – Wave 5, or the joint study of the European Tourism Futures Institute (ETFI – www.etfi.nl) and the Centre of Expertise in Leisure, Tourism and Hospitality (CELTH – www.celth.nl) highlighting four future scenarios for the leisure, tourism and hospitality sectors post COVID-19. The project will look beyond travel intention and will supplement existing knowledge with crucial information on the way consumers view sustainability and the extent to which they are willing to adjust their travel behaviour to aid the recovery of a more sustainable travel and tourism industry. Therefore, the report aims to generate knowledge vital for the understanding of consumer trends and the role sustainability will play in travel choices in the near future.Problem statementPlease describe which question in the (participating) industry is addressed.How has the sustainable travel attitude and behaviour in selected European source markets been influenced by the COVID-19 pandemic? Further questions to be answered:• How did the COVID-19 pandemic influence the consumer’s understanding and appreciation of sustainability?• To what extent did this understanding influence their attitude towards sustainable travel choices?• To what extent is this change represented in their actual and projected travel behaviour throughout the travel decision-making process?• What are the conditions that may foster a more sustainable travel behaviour?
In 2024, the Dutch government set a new plan for offshore wind farms to become the Netherlands' largest power source by 2032, aiming for 21 GW of installed capacity. By 2050, they expect between 38 and 72 GW of offshore wind power to meet climate-neutral energy goals. Achieving this depends heavily on efficient wind turbines (WTs) operation, but WTs face issues like cavitation, bird strikes, and corrosion, all of which reduce energy output. Regular Inspection and Maintenance (I&M) of WTs is crucial but remains underdeveloped in current wind farms. Presently, I&M tasks are done by on-site workers using rope access, which is time-consuming, costly, and dangerous. Moreover, weather conditions and personnel availability further hinder the efficiency of these operations. The number of operational WTs is expected to rise in the coming years, while the availability of service personnel will keep on declining, highlighting the need for safer and more cost-effective solutions. One promising innovation is the use of aerial robots, or drones, for I&M tasks. Recent developments show that they can perform tasks requiring physical interaction with the environment, such as WT inspections and maintenance. However, the current design of drones is often task-specific, making it financially unfeasible for small and medium-sized enterprises (SMEs) – providing services in WT inspection and maintenance- to adopt. Together with knowledge institutes, SMEs and innovation clusters, this project addresses these urgent challenges by exploring the question of how to develop a modular aerial robot that can be easily and intuitively deployed in offshore environments for inspecting and maintaining WTs to facilitate SMEs adoption of this technology? The goal is to create a modular drone that can be equipped with various tools for different tasks, reducing financial burdens for SMEs, improving worker safety, and facilitating efficient green energy production to support the renewable energy transition.
