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Energy efficiency and colour quality improvement and subjective preference of LED office lighting

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Tetri, Eino, Dr., Aalto University, Department of Electrical Engineering and Automation, Finland
dc.contributor.advisor Bhusal, Pramod, Dr., Aalto University, Department of Electrical Engineering and Automation, Finland
dc.contributor.author Baniya, Rupak Raj
dc.date.accessioned 2016-10-14T09:01:34Z
dc.date.available 2016-10-14T09:01:34Z
dc.date.issued 2016
dc.identifier.isbn 978-952-60-7061-2 (electronic)
dc.identifier.isbn 978-952-60-7062-9 (printed)
dc.identifier.issn 1799-4942 (electronic)
dc.identifier.issn 1799-4934 (printed)
dc.identifier.issn 1799-4934 (ISSN-L)
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/22981
dc.description.abstract The objectives of this thesis were to explore different approaches to improve energy efficiency and colour quality, and to find out the subjective preference of LED office lighting. Four approaches (optimization of LED spectra, lighting retrofitting, hue-heat hypothesis, and smart indoor lighting control) were studied for energy efficiency and colour quality improvement. Two experiments, one in lighting booths and the other in an office room, were conducted to examine subjective preferences. In the optimization of LED spectra, simulation work and subjective preference studies conducted in lighting booths suggested that preferred complex LED spectra (realized with 9 to 11 different types of LEDs) found in previous user acceptance studies can be optimized both for efficiency and cost without sacrificing the colour quality of the light. The lighting retrofitting case study showed that by replacing T8 fluorescent luminaires with LED luminaries, and the LED luminaries with inbuilt control systems, energy savings of up to 38% and 68% respectively, can be achieved with improvement of lighting quality and user satisfaction. The experiment conducted to test the hue-heat hypothesis using different correlated colour temperatures (CCTs) of white light did not provide support for the existence of a general correlation between CCT and thermal sensation or thermal comfort and indicated that people felt thermally more comfortable in an indoor workplace at the CCT of 4000 K than at the CCT of 2700 K or 6200 K. A methodology to incorporate data from lighting studies relating colour quality to comfort and productivity to the building automation system has been proposed and demonstrated. The subjective preferences in terms of illuminance and CCT and the CCT preference of three ethnic groups (Asian, European, and African) for LED office lighting were investigated in an office room. Nine different lighting situations (combining 300 lx, 500 lx, and 750 lx with 3000 K, 4000 K, and 5000 K) were compared. The combination of 750 lx with 4000 K was statistically significantly preferred over the other combinations for LED office lighting. It was also found that the CCT of 4000 K was preferred over the CCT of 3000 K for office lighting at 300 lx, 500 lx, and 750 lx. The results indicated that the impression of brightness, the feeling of stimulation, and the impression of spaciousness in office room increases with increased CCT. The study also showed that for office lighting the European group prefer the CCT of 4000 K, and with the Asian and African groups the preference between 4000 K and 5000 K depends upon illuminance levels. en
dc.format.extent 60 + app. 68
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series DOCTORAL DISSERTATIONS en
dc.relation.ispartofseries 206/2016
dc.relation.haspart [Publication 1]: Baniya, R.R; Dangol, R; Bhusal, P; Wilm, A; Baur, E; Puolakka, M; Halonen, L. 2015. User-acceptance studies for simplified light-emitting diode spectra. Lighting Research and Technology, volume 47, number 2, pages 177-191. DOI: 10.1177/1477153513515264
dc.relation.haspart [Publication 2]: Gavioli, M; Tetri, E; Baniya, R.R; Halonen, L. 2015. Lighting Retrofitting: Improving Energy Efficiency and Lighting Quality. In: Proceedings of the 28th Session of the CIE, Manchester, United Kingdom, June 28 – July 4. International Commission on Illumination (CIE). Volume 1, part 2, pages 1903-1910.
dc.relation.haspart [Publication 3]: Baniya, R.R; Tetri, E; Virtanen, J; Halonen, L. 2016. The effect of correlated colour temperature of lighting on thermal sensation and thermal comfort in a simulated indoor workplace. Indoor and Built Environment (Accepted for publication on 19/09/2016). DOI: 10.1177/1420326X16673214
dc.relation.haspart [Publication 4]: Baniya, R.R; Maksimainen, M; Sierla, S; Pang, C; Yang, C. W; Vyatkin, V. 2014. Smart indoor lighting control: Power, illuminance, and colour quality. In: IEEE 23rd International Symposium on Industrial Electronics (ISIE), Istanbul, Turkey, 1-4 June 2014. IEEE. Pages 1745-1750. DOI: 10.1109/ISIE.2014.6864878
dc.relation.haspart [Publication 5]: Baniya, R.R; Tetri, E; Halonen, L. 2015. A study of preferred illuminance and correlated colour temperature for LED office lighting. Light and Engineering, volume 23, number 3, pages 39-47.
dc.subject.other Electrical engineering en
dc.subject.other Energy en
dc.title Energy efficiency and colour quality improvement and subjective preference of LED office lighting en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Sähkötekniikan korkeakoulu fi
dc.contributor.school School of Electrical Engineering en
dc.contributor.department Sähkötekniikan ja automaation laitos fi
dc.contributor.department Department of Electrical Engineering and Automation en
dc.subject.keyword light emitting diode en
dc.subject.keyword energy efficiency en
dc.subject.keyword colour quality en
dc.subject.keyword lighting preference en
dc.subject.keyword correlated colour temperature en
dc.subject.keyword office lighting en
dc.identifier.urn URN:ISBN:978-952-60-7061-2
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Halonen, Liisa, Prof., Aalto University, Department of Electrical Engineering and Automation, Finland
dc.opn Rosemann, Alexander, Prof., Eindhoven University of Technology, The Netherlands
dc.contributor.lab Lighting Unit en
dc.rev Khanh, Tran Quoc, Prof., Technical University of Darmstadt, Germany
dc.rev Onaygil, Sermin, Prof., Istanbul Technical University, Turkey
dc.date.defence 2016-11-11
local.aalto.formfolder 2016_10_14_klo_10_53
local.aalto.archive yes


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