| 1. |
- Aarts, Mariëlle P.J., et al.
(författare)
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Performance of personally worn dosimeters to study non-image forming effects of light : Assessment methods
- 2017
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 117, s. 60-72
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Tidskriftsartikel (refereegranskat)abstract
- 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 directional response index, the linearity index and the temperature index. These indices are also checked for several commonly used portable light measurement devices. The results stresses what was already assumed, the quality and the outcome of these devices under different circumstances were very different. Also, the location were these devices are normally worn has an impact on the results. The deviation range between worn vertically at eye level and the wrist is between 11% (outdoor) to 27% (indoor). The smallest deviation, both in indoor and outdoor, was found when the device was placed on the sides of the eye (7%).
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| 2. |
- Aries, Myriam, et al.
(författare)
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Energy efficient facade lighting : highlighting facade structure
- 2014
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Ingår i: Spool. - 2215-0900. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- The project set out to proof that a conventional optical fibre lighting system for highlighting the structure of a façade can be operated more energy-efficiently through the substitution of the projector using a metal halide reflector lamp by a laser. This is investigated by looking into the photometric assessment of such systems as well as the electric power draw during operation. In preparation for a potential exterior demonstration installation, an additional focal point of the research was the design and testing of a weatherproof case that provides protection to the laser and the ballast. The final stage brought the different aspects of the research together and resulted in a temporary experimental setup (pilot installation) in order to showcase the validity of this novel approach.
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| 3. |
- Chraibi, Sanae, et al.
(författare)
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Satisfying light conditions: a field study on perception of consensus light in Dutch open office environments
- 2016
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 105, s. 116-127
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Tidskriftsartikel (refereegranskat)abstract
- Workplace innovation has been changing the European office landscape into mostly open spaces, where enhanced interaction between people is combined by efficient use of space. However, challenges are found in offering individual preferred conditions in these multi-user spaces, especially when dealing with shared systems.Previous studies clearly show the benefits of personal control as a means to achieve individual preferred lighting. Most of these benefits were demonstrated in private offices or situations where users have a “personal” light source.Lighting systems in open offices are often designed as a regular grid of luminaires to deliver uniform lighting. This often results in a luminaire grid that does not match the desk arrangement, making it challenging to offer personal lighting controls. By grouping luminaires, users could be offered consensus control. The question is whether consensus control brings advantages rather than disadvantages.This paper presents the results of a field study evaluating consensus light control in an open office 14 users experienced a reference no-control condition and a condition with control over a zone of luminaires. Data was collected by objective measurements as well as subjective surveys and interviews.This study shows that consensus control in an open office improves satisfaction of individual users with the light quantity and quality. Even though the controllable light is shared, consensus among users results in an improved lighting environment for the majority of users. Selected illuminances in the condition with controls were on average lower than in the reference condition, resulting in lower energy usage by lighting.
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| 4. |
- de Bakker, Christel, et al.
(författare)
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Occupancy-based lighting control in open-plan office spaces : A state-of-the-art review
- 2017
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 112, s. 308-321
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Tidskriftsartikel (refereegranskat)abstract
- Lighting accounts for a significant amount of electrical energy consumption in office buildings, up to 45% of the total consumed. This energy consumption can be reduced by as much as 60% through an occupant-dependent lighting control strategy. With particular focus on open-plan offices, where the application of this strategy is more challenging to apply due to differences in individual occupancy patterns, this paper covers (1) to which extent individual occupancy-based lighting control has been tested, (2) developed, and (3) evaluated. Search terms were defined with use of three categories, namely ‘occupancy patterns’, ‘lighting control strategy’, and ‘office’. Relevant articles were selected by a structured search through key online scientific databases and journals. The 24 studies identified as eligible were evaluated on six criteria: (1) study characteristics, (2) office characteristics, (3) lighting system characteristics, (4) lighting control design, (5) post-occupancy evaluation, and (6) conclusions, and this was used to answer the research questions. It was concluded that the strategy has not been tested yet with field studies in open-plan offices, but that it needs further development before it can be applied in these type of offices. Although lighting currently tends to be controlled at workspace level, many aspects of the strategy can be further developed; there is potential to further increase energy savings on lighting within open-plan office spaces. Individual occupancy-based lighting control requires further validation, focussing on the factors influencing its energy savings, on its cost effectiveness, and on its acceptability for users.
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| 5. |
- Khademagha, Parisa, et al.
(författare)
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A multidirectional spectral measurement method and instrument to investigate non-image-forming effects of light
- 2018
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Ingår i: Measurement science and technology. - : Institute of Physics Publishing (IOPP). - 0957-0233 .- 1361-6501. ; 29:8
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Tidskriftsartikel (refereegranskat)abstract
- Light directionality, spectrum, and relevant radiometric or photometric quantity are believed essential factors influencing the magnitude of non-image-forming effects. In this paper, a measurement method and an instrument (the multidirectional spectroradiometer - MuS) is proposed, which considers different light incidents and spectra simultaneously, therefore, enables measurement of light characteristics relevant for non-image-forming effects. The MuS consists of four spectroradiometers measuring in different directions. Four spectrometers using optical fibers were configured to measure the spectral irradiance within a wavelength range from 200 to 1100 nm with ~5.7 nm pixel resolution. Application of the MuS facilitates a better understanding of the non-image-forming light characteristics of spaces. The MuS is tested with stable electric lighting and with dynamic daylight conditions and is proven reliable to perform continuous spectral measurements in different directions simultaneously. Results show a substantial difference in measured radiation magnitude and spectral distribution in different directions, which suggests varying impact on non-image-forming effects.
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| 6. |
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| 7. |
- Khademagha, Parisa, et al.
(författare)
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Why Directionality Is an Important Light Factor for Human Health to Consider in Lighting Design?
- 2016
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Ingår i: International Journal of Sustainable Lighting. - : Kyung Hee University. - 2586-1247. ; 35:1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- Both image-forming and non-image-forming effects of radiation require proper attention in lighting design that aims at meeting human vision and health requirements. Intrinsically Photosensitive Retinal Ganglion Cells (ipRGCs) appear to play an essential role in stimulation of the non-image forming effects and thus human health and well-being. There are indications that radiation incident contributes to the magnitude of these effects. This review summarizes current studies on humans and animals related to radiation directionality as well as the spatial distribution of ipRGCs on the retina. New insights can facilitate and optimize the incorporation of radiation directionality in building lighting design.
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| 8. |
- Kruisselbrink, Thijs, et al.
(författare)
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A Practical Device for Measuring the Luminance Distribution
- 2017
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Ingår i: International Journal of Sustainable Lighting. - : Kyung Hee University. - 2586-1247. ; 19:1, s. 75-90
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Tidskriftsartikel (refereegranskat)abstract
- Various applications in building lighting such as automated daylight systems, dynamic lighting control systems, lighting simulations, and glare analyzes can be optimized using information on the actual luminance distributionsof the surroundings. Currently, commercially available luminance distribution measurement devices are often not suitable for these kind of applications or simply too expensive for broad application. This paper describes the development of a practical and autonomous luminance distribution measurement device based on a credit card-sized single-board computer and a camera system. The luminance distribution was determined by capturing High Dynamic Range images and translating the RGB information to the CIE XYZ color space. The High Dynamic Range technology was essential to accurately capture the data needed to calculate the luminance distribution because it allows to capture luminance ranges occurring in real scenarios. The measurement results were represented in accordance with established methods in the field of daylighting. Measurements showed that the accuracy of the luminance distribution measurement device ranged from 5% to 20% (worst case) which was deemed acceptable for practical measurements and broad applications in the building realm.
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| 9. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 10. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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