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Author (up) Cai, W.; Yue, J.; Dai, Q.; Hao, L.; Lin, Y.; Shi, W.; Huang, Y.; Wei, M.
Title The impact of room surface reflectance on corneal illuminance and rule-of-thumb equations for circadian lighting design Type Journal Article
Year 2018 Publication Building and Environment Abbreviated Journal Building and Environment
Volume 141 Issue Pages 288-297
Keywords Lighting
Abstract Recently, corneal illuminance attracts much attention because it is closely related to important functions of indoor lighting. Especially, applying circadian light in the built environment places a challenging requirement on indirect corneal illuminance. In this work, rule-of-thumb equations are proposed to guide circadian lighting design: (i) for artificial lighting, Ecor,avg (i) = (Φ/C1) · ρ/(1−ρ′), where Ecor,avg (i) is the average indirect corneal illuminance at standing or sitting positions, Φ is the initial flux from luminaires, C1 is a constant comparable to the total room surface area, ρ is the reflectance of the surface where the first reflection occurs, and ρ′ is the area-weighted average of surface reflectance; and (ii) for daylighting, Ecor,avg (i) = C2 · WWR · ρ/(1−ρ′), where C2 is a constant, and WWR represents the window-to-wall ratio.

The equations above are validated by comparing against numerical simulation data obtained with the Radiance software. For artificial lighting simulation, various combinations of room surface reflectance, initial light distribution, and WWR are investigated; and for daylighting simulation, different combinations of surface reflectance, WWR, and geographic location are analyzed. The good fits to simulation data indicate that the proposed simple equations can provide reasonably accurate results for quick feedback at the field. It is also demonstrated that room surface reflectance has a dominant impact on indirect corneal illuminance. The approach of improving surface reflectance is more favorable than increasing luminaire flux or expanding window area, and therefore should be the recommended approach to achieve quality and efficient circadian lighting.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0360-1323 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 1929
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Author (up) Cajochen, C.; Frey, S.; Anders, D.; Spati, J.; Bues, M.; Pross, A.; Mager, R.; Wirz-Justice, A.; Stefani, O.
Title Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance Type Journal Article
Year 2011 Publication Journal of Applied Physiology (Bethesda, Md. : 1985) Abbreviated Journal J Appl Physiol (1985)
Volume 110 Issue 5 Pages 1432-1438
Keywords Adult; Circadian Rhythm/*physiology/radiation effects; Cognition/*physiology/radiation effects; *Computer Terminals; Humans; Light; Lighting/*methods; Male; Photic Stimulation/*methods; Radiation Dosage; Semiconductors; *Task Performance and Analysis; Young Adult; blue light; sleep; circadian disruption
Abstract Many people spend an increasing amount of time in front of computer screens equipped with light-emitting diodes (LED) with a short wavelength (blue range). Thus we investigated the repercussions on melatonin (a marker of the circadian clock), alertness, and cognitive performance levels in 13 young male volunteers under controlled laboratory conditions in a balanced crossover design. A 5-h evening exposure to a white LED-backlit screen with more than twice as much 464 nm light emission {irradiance of 0,241 Watt/(steradian x m(2)) [W/(sr x m(2))], 2.1 x 10(13) photons/(cm(2) x s), in the wavelength range of 454 and 474 nm} than a white non-LED-backlit screen [irradiance of 0,099 W/(sr x m(2)), 0.7 x 10(13) photons/(cm(2) x s), in the wavelength range of 454 and 474 nm] elicited a significant suppression of the evening rise in endogenous melatonin and subjective as well as objective sleepiness, as indexed by a reduced incidence of slow eye movements and EEG low-frequency activity (1-7 Hz) in frontal brain regions. Concomitantly, sustained attention, as determined by the GO/NOGO task; working memory/attention, as assessed by “explicit timing”; and declarative memory performance in a word-learning paradigm were significantly enhanced in the LED-backlit screen compared with the non-LED condition. Screen quality and visual comfort were rated the same in both screen conditions, whereas the non-LED screen tended to be considered brighter. Our data indicate that the spectral profile of light emitted by computer screens impacts on circadian physiology, alertness, and cognitive performance levels. The challenge will be to design a computer screen with a spectral profile that can be individually programmed to add timed, essential light information to the circadian system in humans.
Address Centre for Chronobiology, Psychiatric Hospitals of the University of Basel, Basel, Switzerland. christian.cajochen@upkbs.ch
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0161-7567 ISBN Medium
Area Expedition Conference
Notes PMID:21415172 Approved no
Call Number IDA @ john @ Serial 293
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Author (up) Campisi, D.; Gitto, S.; Morea, D.
Title Economic feasibility of energy efficiency improvements in street lighting systems in Rome Type Journal Article
Year 2017 Publication International Journal of Energy Economics and Policy Abbreviated Journal
Volume 7 Issue 1 Pages 190-198
Keywords Economics; Energy; Society; LED lighting; LED; real options
Abstract This study evaluates an investment project concerning the redevelopment of the public lighting of the Municipality of Rome. In particular, we consider the replacing of the traditional lamps of the system with LED lamps. We consider the factors that affect this kind of project: the cost of energy, the manteinance cost, the investment cost and the Weighted Average Cost of Capital (WACC). Our results underline the reduction of energy consumption and of the maintenance costs, lower emissions of CO2 into the atmosphere, the reduction of light pollution, the positive effects on road safety and the indipendence by incentives.
Address Department of Industrial Engineering, University of Rome Tor Vergata, Italy
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ intern @ Serial 2629
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Author (up) Can Duman, A.; Güler, Ö.
Title Techno-economic analysis of off-grid photovoltaic LED road lighting systems: A case study for northern, central and southern regions of Turkey Type Journal Article
Year 2019 Publication Building and Environment Abbreviated Journal Building and Environment
Volume 156 Issue Pages 89-98
Keywords Economics; Lighting; off-grid photovoltaic; LED; Turkey
Abstract Street lighting is one of the sectors where off-grid energy systems are used, and in the past decade interest in these systems has increased due to recent developments occurred both in LED and PV technology. This paper presents a techno-economic analysis of off-grid PV LED road lighting systems for northern, central and southern regions of Turkey. Road lighting calculations are conducted using DIALux software for M4 and M5 road lighting classes to obtain optimal LED luminaires, pole sizes, and spacings. Among the obtained LED powers, load profiles are created using real lighting hours of operation of the selected regions. And then, the required PV-battery systems are optimized using HOMER software. Finally, sensitivity analysis is performed for future projections considering possible increases in electricity prices and decreases in component cost of the PV systems. The results showed that the levelized COE of the off-grid PV LED road lighting systems vary between 0.229 and 0.362 $/kWh. for M4, and 0.254–0.359 $/kWh for M5 road lighting class, depending on the solar potential of the region. And, the total NPC of the entire lighting installation per km vary between 24296 and 29123 $ for M5, and 33225–44318 $ for M4 road lighting class. According to the results, the systems are infeasible under current conditions in Turkey. Nonetheless, they have the added benefits of contributing to the reduction of CO2 emissions. Moreover, future projections show that the systems can be feasible if the declining trend in PV system costs continues and electricity prices increase.
Address Istanbul Technical University, Energy Institute, Ayazaga Campus, 34469, Maslak, Istanbul, Turkey; dumanan(at)itu.edu.tr
Corporate Author Thesis
Publisher Elseiver Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0360-1323 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2292
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Author (up) Cao, D.; Barrionuevo, P.A.
Title The importance of intrinsically photosensitive retinal ganglion cells and implications for lighting design Type Journal Article
Year 2015 Publication Journal of Solid State Lighting Abbreviated Journal J Sol State Light
Volume 2 Issue 1 Pages 10
Keywords Human Health; lighting; Melanopsin; ipRGC; Photoreceptors; Circadian; Visual perception; Color Contrast; Sensitivity; LED; Lighting Design
Abstract We reviewed the role of melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) in light-dependent functions, including circadian rhythm that is important for health and visual perception. We then discussed the implications for lighting design.
Address Visual Perception Laboratory, Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago; dcao98(at)uic.edu
Corporate Author Thesis
Publisher Springer Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2196-1107 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 1325
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