Photoluminescence (PL) properties of NaLi2PO4:Eu3+ phosphor for solid state lighting application

The polycrystalline NaLi2PO4:xEu (x=0.001,0.002,0.005,0.01 and 0.02) phosphors were successfully synthesized via modified solid state diffusion method [MSSDM]. The structural of prepared phosphor was confirmed by using XRD (X-ray diffraction) technique. Additionally, the photoluminescence (PL) behaviors of NaLi2PO4:xEu phosphor was studied.The XRD pattern of prepared phosphor is well matched with JCPDS file.The PL excitation of prepared phosphor was monitored at 618nm while emission was monitored at 393 nm. The effect of different concentrations of Eu3+ ions in NaLi2PO4 phosphor was studies and optimum PL intensity was obtained at x=0.005 mol. of Eu3+ ion. The CIE co-ordinates were calculated and obtained in orange- red region.

Measurement, Simulation, and Quantification of Lighting-Space Flicker Risk Levels Using Low-Cost TCS34725 Colour Sensor and IEEE 1789-2015 Standard

Building owners are transitioning towards a smart lighting solution for illumination purposes. LED (Light Emitting Diode) lighting application has become a norm given its high efficacy and energy efficiencies. This paper presents an approach to monitor the percent flicker conformance of interior building lighting to international standards. The focus is on flickers induced by LED lightings. This experiment utilises a TCS34725 RGB (red, green, blue) colour sensor to measure the flicker parameters of interior lighting spaces. Light-sensitive photodiodes in the sensor detect changes in lighting intensity, and output digitised values. A Raspberry Pi4 minicomputer processes the data measured for comparison to several standards. Non-conformance is reported to building owners to take corrective actions and minimise flicker discomfort exposure to building occupants. A flicker risk level factor is determined to gauge the severity when flickers are present. This method may be used to replace luminaires or fix flickering lighting issues in buildings. The results show that the monitoring system is functional. The proposed measurement and data processing method can be incorporated into any smart building hub for automation and building performance analysis. The method may also be used to measure non-LED lighting flickers.

Assessment of Outdoor Lighting: Methods for Capturing the Pedestrian Experience in the Field

This study assessed whether methods for capturing the pedestrian experience of outdoor lighting, previously evaluated in a full-scale laboratory, were applicable in a real-world setting. It applied an approach capturing the human response to outdoor lighting in a systematic way, by assessing perception, evaluation and behaviour in the lit environment. The study involved 81 participants from two age groups (Young—n: 48, mean age: 26, 63% women; Elderly—n: 33, mean age: 69, 67% women) and was carried out on a pedestrian path in a park in the centre of Malmö, Sweden, in the evenings during wintertime. Two LED lighting applications, differing in light distribution, uniformity and horizontal illuminance, were presented, and the pedestrians’ perception (facial expression recognition and sign reading), evaluation (arousal, valence and perceived outdoor lighting quality) and behaviour (pedestrian flow) were assessed. The results from the perceptual tasks differed significantly between the lighting applications, in favour of the lighting application with greatest uniformity and horizontal illuminance. There was a significant difference in sign reading distance between the two age groups. The methods applied in this study are feasible to administer and could be used to assess lighting solutions in order to capture the needs of vulnerable groups.

Smart Lighting Application for Energy Saving and User Well-Being in the Residential Environment

The idea of smart lighting has emerged over the years in commercial and industrial environments, with a focus on energy saving. With the advancement in technology, smart lighting can now offer opportunities in addition to energy saving to users in home environments for the provision of a comfortable atmosphere and the maintenance of user well-being. Currently, research in the smart lighting field is predominantly dedicated to energy saving in non-residential environments; meanwhile, the residential environments have not been explored. Therefore, a literature review was conducted to provide an overview of smart lighting systems’ effect on energy and well-being in the residential environment. Current research is mostly limited to designing and developing a smart lighting system in a controlled environment, with a limited evaluation of well-being and comfort. The review shows that residential smart lighting application possibilities and opportunities are not widely and thoroughly explored.