Increased Plant Quality, Greenhouse Productivity and Energy Efficiency with Broad-Spectrum LED Systems: A Case Study for Thyme (Thymus vulgaris L.)

A light-emitting diode (LED) system covering plant-receptive wavebands from ultraviolet to far-red radiation (360 to 760 nm, “white” light spectrum) was investigated for greenhouse productions of Thymus vulgaris L. Biomass yields and amounts of terpenoids were examined, and the lights’ productivity and electrical efficiency were determined. All results were compared to two conventionally used light fixture types (high-pressure sodium lamps (HPS) and fluorescent lights (FL)) under naturally low irradiation conditions during fall and winter in Berlin, Germany. Under LED, development of Thymus vulgaris L. was highly accelerated resulting in distinct fresh yield increases per square meter by 43% and 82.4% compared to HPS and FL, respectively. Dry yields per square meter also increased by 43.1% and 88.6% under LED compared to the HPS and FL lighting systems. While composition of terpenoids remained unaffected, their quantity per gram of leaf dry matter significantly increased under LED and HPS as compared to FL. Further, the power consumption calculations revealed energy savings of 31.3% and 20.1% for LED and FL, respectively, compared to HPS. In conclusion, the implementation of a broad-spectrum LED system has tremendous potential for increasing quantity and quality of Thymus vulgaris L. during naturally insufficient light conditions while significantly reducing energy consumption.

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The Color Mixing White-Light LEDs

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.378.440 ◽

2013 ◽

Vol 378 ◽

pp. 440-443

Author(s):

Chiu Jung Yang ◽

Chien Sheng Huang ◽

Chih Wei Chen ◽

Po Wen Chen

Keyword(s):

White Light ◽

Light Emitting Diode ◽

Optical Power ◽

Integrating Sphere ◽

Light Spectrum ◽

Light Emitting ◽

Driver Circuit ◽

Color Mixing ◽

Color Rendering

Thepaperis discussedin coloruniformity study.The experiment divided into two steps in this study,first is modules design and simulation. Second is fabrication and measurement.After measure the LEDs property, calculating the ratio of each colored LEDs by using Grassmanns Law,modeling by Solidworks, and simulating the front study by optical software TracePro.Using four-color mixing with self-developed formula to avoid the present white light emitting diode patent, and the four-color grains are Red, Green, Blue and adding Y to modify the overall quality of the mixed light.The phosphorproduceSteabler-Wronsk hardly in the high temperatureas compared tofour-color mixing.Using four-color mixing to producehigher color rendering index than yellow phosphor.Series-parallel array of grain arrangement adopted to achieve the high demand for uniformity, while simplifying the design conditions by a certain current instead of the general mixed light-driven complex driver circuit,the completion of the mixing module using integrating sphere, light spectrum on the spectrophotometer, optical power, color coordinates values, such as mixing uniformity measurements.The chromaticity coordinates errors after complete results of the mixing module measurement and simulation can be controlled under (0.01x, 0.01y).

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Harmonics and Reduction of Energy Consumption in Lighting Systems by Using LED Lamps

Energies ◽

10.3390/en11113169 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3169 ◽

Cited By ~ 8

Author(s):

Natthanon Phannil ◽

Chaiyan Jettanasen ◽

Atthapol Ngaopitakkul

Keyword(s):

Energy Consumption ◽

Power Quality ◽

Power Factor ◽

Energy Savings ◽

Light Emitting Diode ◽

Total Power ◽

Increase Energy Efficiency ◽

Lighting Systems ◽

Reduction Of Energy Consumption

This paper proposes the study and analysis of harmonics, energy consumption and power quality of light emitting diode (LED) lamps equipped in building lighting systems. LED lamps with external (LED MR16) and internal (LED light bulb) drivers are investigated using an experimental setup to compare the results. The power quality of both LED lamps is studied by using a power quality meter to measure the generated harmonic currents from various case studies. The case study is divided into four major cases: one LED lamp is turned on with one driver, two LED lamps are turned on using the two drivers, eight LED lamps are turned on with one driver, and eight LED lamps are turned on with the eight drivers. As harmonics are related to total power factor (PF), which affects the energy savings of the building, hence, a filtering circuit to reduce harmonic current has been designed and implemented to improve power quality and/or power factor of the system. The different cases of harmonic filter insertion at the input of an LED lamp’s driver are discussed and then compared with a lighting standard to show the effectiveness of the passive filtering technique used in the studied system. In addition, the obtained result can be applied to both newly built and retrofitted buildings that aim to use LED technology to increase energy efficiency and decrease energy costs, and could be a helpful guide for end-users and manufacturers in addressing and developing LED issues.

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A method to estimate savings of led lighting instalation in public buildings: The case study of secondary schools in Serbia

Thermal Science ◽

10.2298/tsci161209118j ◽

2017 ◽

Vol 21 (6 Part B) ◽

pp. 2931-2943 ◽

Cited By ~ 1

Author(s):

Mladen Josijevic ◽

Dusan Gordic ◽

Dobrica Milovanovic ◽

Nebojsa Jurisevic ◽

Nikola Rakic

Keyword(s):

Cost Reduction ◽

Light Emitting Diode ◽

Electric Energy ◽

Light Flux ◽

Electricity Consumption ◽

Maintenance Cost ◽

Light Emitting ◽

Led Lighting ◽

Lighting Systems

This paper examines the potentials of saving electric energy in school lighting by replacing the existent systems of lighting with more adequate ones which are based on light-emitting diode technology. Our primary goal is to present the methodology used in this analysis since it can be used to determine potential savings in lighting systems of any public building. We have performed the detailed analysis of nine high schools located in Kragujevac, Serbia. The first step was to collect the data about the numbers and types of systems utilized, as well as about the habits of their users. This has revealed the share of electricity consumption for lighting in total electricity consumption. The replacements for each existent light source have been proposed taking into consideration the projected value of light flux depending on the purpose of each room. The calculations of potential savings through the replacement of lighting systems have been conducted taking into consideration not only the savings in electric energy but also the savings made through the maintenance cost reduction. Based on the results, the potential savings range from 53-62% while the payback period for the analysed schools is about four years in average.

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Effects of LED light spectra on lettuce growth and nutritional composition

Lighting Research and Technology ◽

10.1177/1477153517701300 ◽

2017 ◽

Vol 50 (6) ◽

pp. 880-893 ◽

Cited By ~ 5

Author(s):

T Hytönen ◽

P Pinho ◽

M Rantanen ◽

S Kariluoto ◽

A Lampi ◽

...

Keyword(s):

Light Emitting Diode ◽

Green Light ◽

Biomass Accumulation ◽

Nutritional Composition ◽

Light Spectrum ◽

Greenhouse Production ◽

Light Emitting ◽

Northern Latitudes ◽

Save Energy

Year-round greenhouse production in northern latitudes depends on the use of artificial lighting. Light emitting diodes provide a promising means to save energy during cultivation as well as to modify the light spectrum to regulate the growth and quality of the crop. We compared the effects of light emitting diode lighting with different spectral compositions on the growth, development and nutritional quality of lettuce ( Lactuca sativa L. ‘Frillice’). We show that warm-white and warm-white supplemented with blue spectra provide equal growth and product quality compared to conventional high-pressure sodium lighting in the absence and presence of daylight. Our data indicate that for biomass accumulation, the far-red component in the light spectrum is more critical than green light or the red/blue ratio. Furthermore, we demonstrate that a red + blue spectrum increases the concentration of several vitamins in lettuce. However, biomass accumulation using this spectrum was insufficient when daylight was excluded.

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Lighting the Patient Room of the Future: Evaluating Different Lighting Conditions From the Patient Perspective

HERD Health Environments Research & Design Journal ◽

10.1177/19375867211063481 ◽

2021 ◽

pp. 193758672110634

Author(s):

Jennifer DuBose ◽

Robert G. Davis ◽

Gabrielle Campiglia ◽

Andrea Wilkerson ◽

Craig Zimring

Keyword(s):

Energy Savings ◽

Light Emitting Diode ◽

Patient Room ◽

Lighting Condition ◽

Light Emitting ◽

Lighting Conditions ◽

Potential Benefits ◽

Lighting Systems ◽

User Friendly

Objective: This study explores whether “future” lighting systems that provide greater control and opportunity for circadian synchronization are acceptable to participants in the role of patients. Background: Tunable, dimmable light emitting diode systems provide multiple potential benefits for healthcare. They can provide significant energy savings, support circadian synchronization by varying the spectrum and intensity of light over the course of the day, address nighttime navigation needs, and provide user-friendly control. There is an emerging understanding of the important visual and nonvisual effects of light; however, important questions remain about the experience and acceptability of this “future” lighting if we are to adopt it broadly. Methods: Volunteer participants (34) performed a series of tasks typical of patients, such as reading or watching a video, in a full-scale simulated inpatient room. Each participant conducted these tasks under 12 lighting conditions in a counterbalanced order that included varying illuminance levels, correlated color temperatures (CCTs), and in a few conditions, saturated colors. The participants rated each lighting condition on comfort, intensity, appropriateness, and naturalness. Results and Conclusions: The participants found that conditions with CCTs of 5,000 K and higher were significantly less comfortable and less natural than conditions with lower CCTs. Conditions with lighting distributed in multiple zones in the patient room were viewed more favorably than a traditional overbed configuration. The participants in this simulated patient study reacted negatively to colored lighting on the footwall of the room but found a mixture of warmer and cooler luminaire CCTs acceptable.

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Temperature and Humidity Dependent Reliability Analysis of RGB LED Chips

ISTFA 2006: Conference Proceedings from the 32nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2006p0137 ◽

2006 ◽

Author(s):

Jun-Xian Fu ◽

Shukri Souri ◽

James S. Harris

Keyword(s):

Reliability Analysis ◽

Printed Circuit Board ◽

Light Emitting Diode ◽

Circuit Board ◽

Light Emitting ◽

Printed Circuit ◽

Root Cause ◽

Micro Cracks ◽

Temperature And Humidity

Abstract Temperature and humidity dependent reliability analysis was performed based on a case study involving an indicator printed-circuit board with surface-mounted multiple-die red, green and blue light-emitting diode chips. Reported intermittent failures were investigated and the root cause was attributed to a non-optimized reflow process that resulted in micro-cracks and delaminations within the molding resin of the chips.

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Using the private finance initiative for energy efficiency projects at the urban scale

International Journal of Energy Sector Management ◽

10.1108/ijesm-12-2014-0005 ◽

2016 ◽

Vol 10 (1) ◽

pp. 99-117 ◽

Cited By ~ 11

Author(s):

Alberto De Marco ◽

Giulio Mangano ◽

Fania Valeria Michelucci ◽

Giovanni Zenezini

Keyword(s):

Energy Efficiency ◽

Urban Areas ◽

Light Emitting Diode ◽

Project Finance ◽

Private Finance Initiative ◽

Content Type ◽

Light Emitting ◽

Alternate Forms ◽

Private Investors

Purpose – The purpose of this paper is to suggest the usage of the project finance (PF) scheme as a suitable mechanism to fund energy efficiency projects at the urban scale and present its advantages and adoption barriers. Design/methodology/approach – A case study is developed to renew the traffic lighting system of an Italian town via replacement of the old lamps with new light-emitting diode (LED) technology. Several partners are involved in the case project to construct a viable PF arrangement. Findings – The case study presents the viability of the proposed PF scheme that provides for acceptable financial returns and bankability. However, it also shows that the need for short concession periods may call for a public contribution to the initial funding to make the project more attractive to private investors. Practical implications – This case study is a useful guideline for governments and promoters to using the PF arrangement to fund energy efficiency investments in urban settings. It helps designing an appropriate PF scheme and understanding the advantages of PF to reduce risk and, consequently, increase the debt leverage and profitability of energy efficiency projects. Originality/value – This paper contributes to bridging the gap about the lack of works addressing the implementation of the PF mechanism in the energy efficiency sector in urban areas. The importance of this paper is also associated with the shortage of traditional public finance faced by many cities that forces to seek for alternate forms of financing.

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A Supervisory Control Strategy for Improving Energy Efficiency of Artificial Lighting Systems in Greenhouses

Energies ◽

10.3390/en14010202 ◽

2021 ◽

Vol 14 (1) ◽

pp. 202

Author(s):

Gianluca Serale ◽

Luca Gnoli ◽

Emanuele Giraudo ◽

Enrico Fabrizio

Keyword(s):

Control Strategy ◽

Light Emitting Diode ◽

Cost Savings ◽

Energy Performance ◽

Lighting System ◽

Light Emitting ◽

Artificial Lighting ◽

Lighting Control ◽

Lighting Systems ◽

Power Densities

Artificial lighting systems are used in commercial greenhouses to ensure year-round yields. Current Light Emitting Diode (LED) technologies improved the system efficiency. Nevertheless, having artificial lighting systems extended for hectares with power densities over 50W/m2 causes energy and power demand of greenhouses to be really significant. The present paper introduces an innovative supervisory and predictive control strategy to optimize the energy performance of the artificial lights of greenhouses. The controller has been implemented in a multi-span plastic greenhouse located in North Italy. The proposed control strategy has been tested on a greenhouse of 1 hectare with a lighting system with a nominal power density of 50 Wm−2 requiring an overall power supply of 1 MW for a period of 80 days. The results have been compared with the data coming from another greenhouse of 1 hectare in the same conditions implementing a state-of-the-art strategy for artificial lighting control. Results outlines that potential 19.4% cost savings are achievable. Moreover, the algorithm can be used to transform the greenhouse in a viable source of energy flexibility for grid reliability.

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Light Emitting Diodes (LEDs) as Agricultural Lighting: Impact and Its Potential on Improving Physiology, Flowering, and Secondary Metabolites of Crops

Sustainability ◽

10.3390/su13041985 ◽

2021 ◽

Vol 13 (4) ◽

pp. 1985

Author(s):

Musa Al Murad ◽

Kaukab Razi ◽

Byoung Ryong Jeong ◽

Prakash Muthu Arjuna Samy ◽

Sowbiya Muneer

Keyword(s):

Crop Production ◽

Morphological Changes ◽

Light Emitting Diode ◽

Crop Productivity ◽

Photon Flux ◽

Flower Initiation ◽

Nutrient Metabolism ◽

Light Emitting ◽

Cultivation Systems ◽

Lighting Systems

A reduction in crop productivity in cultivable land and challenging environmental factors have directed advancement in indoor cultivation systems, such that the yield parameters are higher in outdoor cultivation systems. In wake of this situation, light emitting diode (LED) lighting has proved to be promising in the field of agricultural lighting. Properties such as energy efficiency, long lifetime, photon flux efficacy and flexibility in application make LEDs better suited for future agricultural lighting systems over traditional lighting systems. Different LED spectrums have varied effects on the morphogenesis and photosynthetic responses in plants. LEDs have a profound effect on plant growth and development and also control key physiological processes such as phototropism, the immigration of chloroplasts, day/night period control and the opening/closing of stomata. Moreover, the synthesis of bioactive compounds and antioxidants on exposure to LED spectrum also provides information on the possible regulation of antioxidative defense genes to protect the cells from oxidative damage. Similarly, LEDs are also seen to escalate the nutrient metabolism in plants and flower initiation, thus improving the quality of the crops as well. However, the complete management of the irradiance and wavelength is the key to maximize the economic efficacy of crop production, quality, and the nutrition potential of plants grown in controlled environments. This review aims to summarize the various advancements made in the area of LED technology in agriculture, focusing on key processes such as morphological changes, photosynthetic activity, nutrient metabolism, antioxidant capacity and flowering in plants. Emphasis is also made on the variation in activities of different LED spectra between different plant species. In addition, research gaps and future perspectives are also discussed of this emerging multidisciplinary field of research and its development.

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