Light Emitting Diode Luminaires Research Articles

Study of LED Retrofit Lamps in HSPV Luminaires Based on Photometric Method for Road Lighting

Energy reduction is a great challenge in road lighting applications. Replacing high-pressure sodium vapor (HPSV) with light-emitting diodes (LED) is a viable approach to reducing energy consumption. However, a total replacement can incur a significant capital cost. This study aims to investigate the effects on light distribution by replacing HPSV lamps with LED lamps in HPSV luminaires using Light Intensity Distribution (LID) curve measurement and Backlight, Uplight and Glare (BUG) rating evaluation to reduce the adoption costs. While LED lamps have high illumination rates, the structural differences from HPSV lamps can affect the LID curve and original lighting design. Therefore, it is crucial to study photometric dispersion after retrofitting light sources. Both lamps were installed into similar HPSV luminaires to assess photometric performance using goniophotometer measurements. The HPSV lamp outperforms the LED lamp in terms of luminous flux (11.13%) and light intensity (7.69%), whereas the LED lamp outperforms the HPSV lamp in terms of efficacy rating (68.67%) and wattage used (47.61%). The findings indicate that retrofit LED luminaires have an LOR of 46.77% lower than the HPSV luminaires. The light distribution pattern is maintained but reduced to 40 to 50% for the main usable light angles. The reduced performance is caused by the lamp structure, which occupies a large area inside the luminaire housing, obstructing proper light distribution. Although overall energy consumption is reduced, similar illumination levels cannot be maintained. These outcomes can assist authorities and manufacturers with alternative methods of reducing costs while maintaining lighting levels.

Evaluating Emerging Spectral Lighting Software: Comparing Measurements of Light Spectrum and Derived Metrics in a One-Room Laboratory Environment with Simulation Results

ABSTRACT The goal of this study was to evaluate the use of new spectral simulation tool, Adaptive Lighting for Alertness (ALFA), by comparing software-predicted values of spectral irradiance, illuminance, and equivalent melanopic lux (EML) to corresponding measurements captured in a laboratory environment with light-emitting diode (LED) luminaires. Four lighting conditions were considered by varying the correlated color temperature (CCT) of the LED luminaires. Meter measurements of space geometry, spectral reflectance distribution (SRDs) of materials, and spectral power distribution of luminaires were used as input to the simulation. Simulated spectral irradiance values between 400 and 700 nm were generally within 10% of measured values, with many spectral bands having less than 5% error. Larger mean absolute percent error (MAPE) was observed for the mixed lighting conditions for bands between 420 and 490 nm, which subsequently influenced calculated EML values. Compared to horizontal measurements, vertical measurements were particularly susceptible to additional error through the measurement procedure and measurement equipment.

Life cycle cost analysis of LED retrofit and luminaire replacements for four-foot T8 troffers

Lighting makes up 17% of electrical loads and the largest energy end use in commercial buildings. Linear fixtures are among the largest opportunities for energy efficiency improvement, given their long operating hours. With continued, rapid light-emitting diode (LED) development and more LED replacement products on the market, lighting replacement decisions become more complex and warrant re-examination. With a goal to inform building managers and other decision-makers with practical guidance on lighting replacement, this study is a life cycle cost (LCC) analysis that compares the cost–benefit of six replacement options (one fluorescent and five LED) for a 0.61 m by 1.22 m (2 ft by 4 ft) T8 recessed troffer based on data for 168 lighting products from an online vendor. Results show that direct wire (i.e. unballasted) LED retrofits are the least-cost option to replacing fluorescent lamps in terms of normalized LCC. Plug-and-play lamps suffer from a lock-in with ballasts, but their ease of installation can help spur LED adoption. In cases where an existing ballast is still usable, hybrid LED retrofits provide the least upfront cost option by deferring the cost of rewiring. LED luminaires can offer improved aesthetics and reliability; however, they have high upfront cost. Among them, luminaires with replaceable lamps offer lower cost than those without.

Research Note: Irritating flashing light or poultry-friendly lighting—are flicker frequencies of LED luminaires a potential stress factor in the husbandry of male fattening turkeys?

Conventional fluorescent tubes are increasingly being replaced with innovative light-emitting diodes (LEDs) for lighting poultry houses. However, little is known about whether the flicker frequencies of LED luminaires are potential stressors in poultry husbandry. The term "light flicker" describes the fluctuations in the brightness of an electrically operated light source caused by the design and/or control of the light source. In this context, the critical flicker frequency (CFF) characterizes the frequency at which a sequence of light flashes is perceived as continuous light. It is known that CFF in birds is higher than that in humans and that light flicker can affect behavioral patterns and stress levels in several bird species. As there is a lack of knowledge about the impact of flicker frequency on fattening turkeys, this study aimed to investigate the effects of flicker frequency on the behavior, performance, and stress response in male turkeys. In 3 trials, a total of 1,646 male day-old turkey poults of the strain B.U.T. 6 with intact beaks were reared for 20 wk in 12 barn compartments of 18 m² each. Each barn compartment was illuminated using 2 full-spectrum LED lamps. Flicker frequencies of 165 Hz, 500 Hz, and 16 kHz were set in the luminaires to illuminate the compartments. Analyses of feather corticosterone concentration were performed on fully grown third-generation primaries (P 3) of 5 turkeys from each compartment. No significant differences were found in the development of live weight, feed consumption, or prevalence of injured or killed turkeys by conspecifics reared under the above flicker frequencies. The flicker frequencies also did not significantly influence feather corticosterone concentrations in the primaries of the turkeys. In conclusion, the present results indicate that flicker frequencies of 165 Hz or higher have no detrimental effect on growth performance, injurious pecking, or endocrine stress response in male turkeys and, thus, may be suitable for use as animal-friendly lighting.

Reducing Lighting Energy Use in Controlled Agricultural Environments

Photometric simulations using both daylight and electric lighting were performed to compare the energy use of conventional high-pressure sodium (HPS) greenhouse lighting to that of light-emitting diode (LED) lighting. Photometric simulations of a hypothetical greenhouse were performed in three different geographic locations in the United States with widely different annual daylight availability: Albany, NY, Fairbanks, AK, and Phoenix, AZ. Simulation conditions included summer and winter, overcast and clear skies, and several lighting layouts and distributions. The analysis showed that, while maintaining the criteria levels of photosynthetic photon flux density, lighting energy savings were primarily attributable to increased LED source efficacy rather than HPS. Secondary energy savings were attributable to the ability to continuously dim LED lighting in response to daily and seasonal changes in daylight. Despite options for LED luminaires with a slim form factor, reduced crop shading compared with larger conventional HPS luminaires did not result in significant lighting energy savings.

Modeling of Hybrid Henry Gas Solubility Optimization Algorithm with Deep Learning-Based LED Driver System

Light emitting diodes (LEDs) have become an effective lighting solution because of the characteristics of energy efficiency, flexible controllability and extended lifetime. They find use in numerous lighting systems for residents, industries, enterprises and street lighting applications. The efficiency and trustworthiness of the LED systems considerably based on the thermal mechanical loading improved several degradation schemes and respective interfaces. The complication of the LED systems limits the theoretic interpretation of the core reasons for the luminous variation or the formation of the direct correlation among the thermal aging loading and the luminous output. Therefore, this paper designs a new hybrid Henry gas solubility optimization with deep learning (HHGSO-DL) algorithm for LED driver system design. The presented HHGSO-DL technique mainly concentrates on the derivation of empirical relationships among the design parameters, thermal aging loading and luminous outcomes of the LED product. In the presented HHGSO-DL technique, bidirectional long short-term memory (BiLSTM) algorithm is executed for examining the empirical relationship and its hyperparameters can be tuned by the HHGSO algorithm. In this work, the HHGSO algorithm is derived by the integration of traditional HGSO algorithm with oppositional-based learning (OBL) concept. The performance of the HHGSO-DL technique can be investigated on LED chip packaging and LED luminaire with thermal aging loading. The extensive results demonstrate the promising performance of the HHGSO-DL technique over other state-of-the-art approaches.

Calculation and Selection of Spectral Characteristics of Radiation of LED Luminaires for Operation Rooms

Many researchers considered improvement of colour discrimination an important factor of surgery illumination, but none of them provided data on colour contrast estimation. The article describes the results of an extensive search of spectrum that are the most preferable for application in surgery equipment using selected light emitting diodes (LED) of different types. The search was not also based on the qualitative characteristics recommended by the standard, but also on a previously non-considered parameter: colour contrast between human tissues K estimated in uniform-chromaticity systems. The programme developed in MATLAB environment allows to model the cumulative spectrum of a LED light source, to determine the proportions of LED radiation or crystals in LED providing the maximum value of LED general colour rendering index Ra at the set correlated colour temperature or the maximum value of averaged K in uniform-chromaticity systems both in presence of the limited Ra value of 85 and if there are no limitations. Such options of spectrum search allowed to evaluate the probability of K change and its maximum, as well as to identify three possible operating modes of surgery equipment when using the said LEDs. The first of them is following the existing recommendations for Ra with possible insignificant change of K, the second one is the priority of K assuming violation of the Ra recommendations to increase K, and the third option assumes switching between the modes if necessary. LED spectra are selected for such different modes. Other colour rendering indexes are also estimated, and the authors recommend using the new standard TM‑30–15 for standardisation of the colour rendering quality of light sources used in surgery luminaires. It is based on 99 samples and some of the tests have reflective properties close to those of human tissues.

Characterization of Spectroradiometric Based Luminous Flux Measurements for LED Luminaires at BRIN Indonesia

Light Emitting Diode (LED) luminaires are known to have higher efficacy compared to other types of light sources. Therefore, this type of luminaire has been deployed to replace existing conventional types of light sources as means of energy-saving around the world. LED efficacy is commonly measured using a photometer mounted in a goniophotometer or an integrating sphere system. However, due to the different spectral properties of the LEDs compared with the source used in the photometer calibration, mismatch correction needs to be applied in the measurement process. Due to the arduous process of obtaining the correction, the measurement of luminous flux using a spectroradiometer is proposed in this study. By utilizing this device, the mismatch correction does not need to be applied. The measurements of several commercially available LED and energy-saving compact fluorescent luminaires (CFL) show that current LED has twice the efficacy of the CFLs. The LED shows efficacy in the range of 114 lumen/watt. The measurement uncertainty associated with the efficacy of the LED is 4.2%. It is expected that the quality assurance and the accuracy of LEDs luminaires measurement and testing in Indonesia can be improved by using the integrating sphere with the spectroradiometer measurement method.

Pulsed-lighting LED luminaire for agriculture with a geometrical optical solution.

Light-emitting diodes (LEDs) are the 4th plant supplemental lighting source. Pulsed lighting is benefit to increase energy utilization efficiency in greenhouse production. A pulsed-lighting LED luminaire with geometrical optical solution is proposed to overcome the shortcoming with pulse width modulation (PWM) solution. In addition, this luminaire also achieves uniform lighting by designing optical surfaces. In the illumination area, the lighting frequency is 117.6 Hz and the illuminance uniformity is 0.789, which is better than 0.75 (+/- 12.5%). In an actual planting experiment of Brassica chinensis, the average fresh weight of the plants under the pulsed-lighting LED luminaire was 33.1% higher than that under the conventional LED luminaire. The results showed that the energy utilization efficiency of the pulsed-lighting LED luminaire is 22.9% higher than that of the conventional LED luminaire.

Modelling of the effects of luminaire installation geometries and other factors on road illumination system photometric parameters and energy efficiency

PurposeProperly planned road illumination systems are collectively a public wealth and the commissioning of such systems may require extensive planning, simulation and testing. The purpose of this simulative work is to offer a simple approach to facilitate luminance-based road lighting calculations that can be easier to comprehend and apply to practical designing problems when compared to complex multi-objective algorithms and other convoluted simulative techniques.Design/methodology/approachRoad illumination systems were photometrically simulated with a created model in a validated software platform for specified system design configurations involving high-pressure sodium (HPS) and light-emitting diode (LED) luminaires. Multiple regression analyses were conducted with the simulatively obtained data set to propound a linear model of estimating average luminance, overall uniformity of luminance and energy efficiency of lighting installations, and the simulatively obtained data set was used to explore luminaire power–road surface average luminance characteristics for common geometric design configurations involving HPS and LED luminaires, and four categories of road surfaces.FindingsThe six linear equations of the propounded linear model were found to be well-fitted with their corresponding observation sets. Moreover, it was found that the luminaire power–road surface average luminance characteristics were well-fitted with linear trendlines and the increment in road surface average luminance level per watt increment of luminaire power was marginally higher for LEDs.Originality/valueThis neoteric approach of estimating road surface luminance parameters and energy efficiency of lighting installations, and the compendia of luminaire power–road surface average luminance characteristics offer new insights that can prove to be very useful for practical purposes.

Towards intelligent illumination systems: from the basics of light science to its application

The development and design of lighting systems is closely linked to the physiology of the human visual system. Whereas with the first generation of light sources, the visual appearance of objects in an illuminated environment was only possible by adjusting the level of illuminance. In contrast, with modern semiconductor light-emitting diode (LED) systems, the emitted spectrum can be flexibly varied. This new degree of freedom has led to an interdisciplinary field of research, aiming to explore the effect of light on humans in terms of physiological, psychological and cognitive parameters and to model their mechanisms or make them quantifiable via mathematical metrics. Today’s quality assessment of light spectra is composed of metrics that combine colour perception, contrast sensitivity, visual sensation, non-visual responses and cognitive preference. A lighting system that takes these aspects into account is commonly referred to as an integrative lighting solution or Human Centric Lighting. This article describes the current knowledge about the human eye’s visual and non-visual processing system, the development of colour rendering metrics, and the light-induced effect on nocturnal melatonin suppression. Then, the basic concept of an intelligent and individually adaptable lighting system will be discussed.Practical Relevance: This article deals with the basics of light science and covers the fundamental aspects of intelligent lighting systems, which with the help of multi-channel LED luminaires, could address the visual properties of light and the human circadian system separately via metameric spectra.

Arrangement of LEDs and Their Impact on Thermal Operating Conditions in High-Power Luminaires

Solid-state light sources are currently the fastest-growing group of light sources, replacing the previously used discharge and incandescent light sources. Thermal operating conditions of LEDs (Light Emitting Diode) play an important role in t maintaining long service life and constancy of luminous-electrical parameters. In the field of illumination, the service life parameter of light sources is important for the costs of maintenance of the illumination system, while the maintenance of the value of certain light parameters over time, such as luminous flux, color temperature and color rendering index, is related to the aesthetic effect of the illumination. In addition, limiting the junction temperature of solid-state light sources is particularly important in high-power luminaires dedicated to flood illumination. One of the elements shaping the thermal operating conditions of multi-source LED luminaires is the number of luminaires used, their arrangement, and the distance between LEDs installed on the MCPCB (Metal Core Printed Circuit Board) substrate. This article presents the results of simulation studies, realized using CFD (Computational Fluid Dynamics) software, where the temperature distribution and the junction temperature of the LED panel were determined for different configurations and distances between the LEDs. The results obtained were analyzed and conclusions were drawn based on them. Thermal tests performed and presented in the article cover scientific issues related to shaping the temperature distribution of the LED panel. They make it possible to determine the influence of thermal couplings between the sources, related to their number, distance and the value of the forward current, on the final temperature of the LED junction temperature. The presented research results may constitute auxiliary materials for designers of lighting luminaires, especially high-power luminaires, where a large number of high-power LED sources are installed in close proximity.

Comparative Analysis of High-Pressure Sodium Vapor Luminaires with LED Luminaires in Tunnel Illumination

Nowadays, some roads pass through underground tunnels due to technical inadequacy and high economic costs in constructing highways, railways, and pedestrians. Tunnels are opened to pass through obstacles on the route (mountain, hill, etc.) to force the driver, disturb him, reduce the ramps that could endanger safety depending on nature’s state, and shorten travel distances. In this way, number of tunnels along with the road increases, and illuminating these tunnels with different characteristics varies day and night. Tunnel illumination calculations and applications are essential as good tunnel illumination ensures the same flow of comfort, speed, and safety as on the approaching road. Moreover, with the advancement of tunnel technology, many types of equipment are used inside and outside the tunnel, and electricity needs vary according to these types of equipment. In this research, the importance of tunnel illumination was discussed and comparative illumination analysis in 8 August tunnel in Bitlis was conducted. Illumination for the Bitlis 8 August tunnel was done using luminaires with high-pressure sodium vapor lamps, and the grid was used to generate all the energy required. In this study, the energy used by the Bitlis 8 August tunnel for illumination was obtained from the accurate data and the results were compared with the initial situation when the same system was installed using light emitting diode (LED) illumination technology.

Experimental Design and Analysis of Adaptive LED Illumination System

Light emitting diode (LED) luminaires are widely used in street, road, and tunnel illumination. It is necessary to detect their negative effects on power grid, especially in terms of power quality distortions. In addition, because of the limited energy sources, they have to be operated in most efficient way. This paper proposed an adaptive illumination system that can be used in highway tunnels. In this context, an experimental system that consist of LED luminaires with various power values that are possible to be used in tunnel illumination was implemented. Scenarios have been created for the designed system in accordance with possible tunnel illumination scheme. Siemens S7–1200 PLC was used to control these scenarios. FFT analysis of the measurements obtained with adaptive illumination scenarios was performed and power quality distortions were determined for different harmonic levels. Similar analysis was repeated for the non-adaptive system, and a detailed comparison was proposed. In addition, both systems were compared in terms of energy consumption. Operational characteristics of adaptive illumination systems were discussed by using the obtained data. Results show that total harmonic distortion (THD) for all luminaires are active situation is quite lower than adaptive illumination scenarios, where the values of current THD are 149.7 %, 119.9 %, and 85.8 % that scenario 1, scenario 2, and all luminaires are in active situation, respectively. On the other hand, as advantage, a power saving of 73.4 % and 60.3 % can be achieved compared to different adaptive illumination scenarios according to all luminaires are active.

Thermal modelling of multicolor LED luminaire via scaling of a heat sink to aid user wellness

Light Emitting Diode (LED) based lighting luminaires with efficient thermal management deliver high color renderance and inherit longevity. Thermal management is associated with the design of heat sink to extract the heat. This paper focuses on scaling heat sink baseplate and fin height to enhance the thermal management of multicolor LED luminaire. The heat sink fin height is scaled at three levels 10 mm, 15 mm and 20 mm with its base plate characterized at 1 mm, 1.5 mm and 2 mm. This two-dimensional scaling showed that the base plate thickness of 2 mm and fin height of 20 mm delivered high heat dissipation of 70.2828 °C on LED chip and Color Rendering Index (CRI) Ra 94.83 at correlated color temperature 4500 K, 500 lux. In addition to it the conceptual design demonstrated color point stability with low lumen degradation. This progressive study on thermal and color performance by scaling luminaire heat sink is an epoch to build energy and thermal efficient luminaire.

Measurement of Power Frequency Current including Low- and High-Order Harmonics Using a Rogowski Coil.

The measurement of a power frequency current including low- and high-order harmonics is of great importance in calibration as well as in testing processes. Therefore, this paper presents the measurement of the power frequency current of light-emitting diode (LED) luminaires. LED luminaires were chosen as their input current includes both low- and high-order harmonics. The measurement process depends on reconstructing an LED luminaire current without using the coil parameters. Hence, the current reconstruction process is designed to be dependent on the measured characteristics of the Rogowski coil itself considering the frequency range at which the measurement process is required. An evaluation of the proposed measurement process was theoretically and experimentally carried out. A theoretical evaluation was carried out using MATALB SIMULINK software. However, the experimental evaluation was performed by building a Rogowski coil to measure the input currents of different LED luminaires having different power ratings of 300 W, 400 W, and 600 W. The currents measured using the Rogowski coil were compared with reference currents measured using a standard measurement technique. The obtained results show the efficacy of the proposed measurement method.

Optimization of Receivers' Field of Views in Multi-User VLC Networks: A Bio-Inspired Approach

Visible light communication is a well-known emerging technology that enables high data rate wireless access in indoor environments by making dual-us e of light-emitting diode luminaires for providing lighting and communication. Managing multiple access and addressing the user's mobility are among the current challenges of this technology. To manage multiple access interference arising from unintended received signals of other users, different approaches have been proposed so far, including zero-forcing precoding and broadcasting of the users' signals. However, by this approach, the network performance is sensitive to the users' locations, since they affect the correlation properties of the network channel matrix. A higher correlation (e.g., for the case of users getting closer together) results in a performance degradation. To mitigate this, we propose a novel approach of optimizing the receivers field-of-views based on the bio-inspired particle swarm optimization in order to adapt to the users' location, and hence, improve the network's robustness. The efficiency of the proposed method is demonstrated through numerical simulations.

A new LED luminaire system architecture for energy saving

This study evaluated a new light-emitting diode (LED) luminaire system architecture in low profile to harvest the otherwise wasted heat generated by LEDs for integrative lighting and heating in buildings. A portable calorimeter was built, commissioned and calibrated in a well-controlled Cold Room for measuring the ‘conditioned space/ceiling plenum split’ of the heat generated by LED luminaires. Two prototypes LED luminaires that adopted the new system architecture were tested together with two off-the-shelf commercial LED luminaires with conventional system architectures for comparison. Each luminaire was either ceiling recessed or ceiling surface mounted in the calorimeter, both were evaluated in summer and winter conditions. The measured ‘conditioned space/ceiling plenum split’ was then used as an input in Energy Plus, with two assumptions, for estimation of the annual heating, reheating and cooling energy consumptions of each luminaire once implemented in a primary school classroom. The simulation results revealed that the new luminaire system architecture especially when surface mounted can outperform the conventional architectures to slightly reduce the building annual heating and reheating energy consumptions without significantly increasing cooling energy consumption. This study validated the potential of integrative lighting and heating. Further studies are necessary to overcome several limitations.

Wireless Sensor Actuator Network Architecture and Energy Model of a Camera Based Lighting Management System

Communication protocols and wireless networking technique is a cohesive part of any light management system. IEEE 802.15.4 standard based networking techniques for the climate-adaptive light management system and its energy model for sensor actuator node is the focus of this paper. This light integrated scheme with adaptive controls provides the desired illuminance at appropriate times with uniformity, by reducing the discomfort glare and energy use. The first part of this paper investigates the architecture and energy consumption of camera-based wireless sensor-actuator nodes with the help of energy models, including a control unit for the Light Management System. Then focused on the energy savings and techno-economic analysis of this wireless networked lighting system in a test room with automated control of Light Emitting Diode luminaire and Venetian blinds. The wireless sensor actuator networked lighting system performance is analyzed by evaluating the node energy consumption in idle and active mode with real time measurements. The energy consumption evaluation of the nodes allows users to improve node life time and think about power management schemes. The climate-adaptive control scheme shows improved uniformity and significant energy savings.

Study of glaring effect from light emitting diodes via lens approach

The purpose of this study was to evaluate the glaring effect from light-emitting diode (LED) streetlight with two different brands of lens (Lens A and Lens B). By using DIALux Evo with 70W LED luminaires, same scenarios of road lighting designs with pole distance of 35m and pole heights of 10 m on a 7 m wide road was evaluated from both the lenses. Calculation was performed on a section defined by one pole on one side of the road (single row). The pole height, light overhang and boom length were 10m, 1m and 1.5m, respectively. The light loss factor was 0.80. TracePro was used to simulate the distribution of light by tracing rays. All mounted luminaries have three zones of light output which are backlight, uplight and frontlight. Both frontlight and backlight sub-zones are factored into the glare rating. Lens B demonstrated a better threshold increment (8) and the lowest lumens for glare rating as compared to Lens A. This was due to the shape of lens. Smaller shape of lens contributes to narrower light distribution patterns as well as smaller average beam angle, suggesting that Lens B was more suitable for LED streetlights.