Light-emitting Diode Lamps Research Articles

Color-tunable transparent photovoltaics for onsite power production under sunlight and indoor light

Transparent photovoltaics (TPVs) are energy-generating devices made of transparent material and incorporating solar cell technology. The ultimate goal of using such devices is to reach a level of sustainability by harnessing energy from common structures such as windows on buildings and vehicles. Applications of this concept can be widened by incorporating a color-tuning scheme into TPVs. In this sense, light can be managed; here, we introduce a method for this using a ZnO-based back reflection method. Large-scale (16 cm2) TPVs are achieved by solid-state sputtering of metal oxide layers. They exhibited high power conversion efficiency (η) (3.8% for indoor light-emitting diode lamp) and long-term stability (>100 days). The abrupt heterojunction between n-type ZnO and p-type NiO spontaneously forms a space charge region with a strong electric field. An additional thin Si film in the heterojunction effectively improves solar cell performance, making it useful for power generation, even under indoor illumination. Substantial efficiency of 3.02% was achieved by an Al-doped ZnO for the Sun spectrum. This implies the ability to produce TPV power from the Sun or artificial light in versatile ways. TPVs and color-tuned photovoltaics can be used in windows and other such objects to realize an onsite power supply.

Physiological and Transcriptomic Analysis Revealed the Molecular Mechanism of Pinus koraiensis Responses to Light.

Korean pine (Pinus koraiensis Sieb. et Zucc.), as the main tree species in northeast China, has important economic and ecological values. Currently, supplementary light has been widely used in plant cultivation projects. However, the studies about different supplementary light sources on the growth and development of Korean pine are few. In this study, the one with no supplementary light was used as the control, and two kinds of light sources were set up: light-emitting diode (LED) and incandescent lamp, to supplement light treatment of Korean pine. The spectrum and intensity of these two light sources were different. The results showed that the growth and physiological-biochemical indicators were significantly different under different supplementary light treatments. The biomass of supplementary light treatment was significantly lower than the control. Compared with the control, IAA and GA were lower, and JA, ABA, ZT, and ETH were higher under supplementary light conditions. Photosynthetic parameters in supplementary light conditions were significantly lower than the control. Supplemental light induces chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid accumulation. From RNA-seq data, differentially expressed genes (DEGs) were observed in all the comparison groups, and there were 487 common DEGs. The expression levels of DEGs encoding transcription factors were also changed. According to GO and KEGG analysis, the plant hormone signal transduction, circadian rhythm-plant, and flavonoid biosynthesis pathways were the most enriched. These results provided a theoretical basis for the response of Korean pine to different supplementary lights.

Smart Dimmable LED Lighting Systems.

This paper proposes energy-efficient solutions for the smart light-emitting diode (LED) lighting system, which provides minimal energy consumption while simultaneously satisfying illuminance requirements of the users in a typical office space. In addition to artificial light from dimmable LED lamps, natural daylight coming from external sources, such as windows, is considered as a source of illumination in an indoor environment. In order to reduce total energy consumption, the smart LED system has the possibility to dim LED lamps, resulting in reduced LED output power. Additionally, various LED lamps' functionality, such as semi-angle of the half illuminance and LED tilting, are introduced as an additional parameter to be optimized to achieve greater energy saving of the designed system. In order to properly exploit external lighting, the idea to reduce overall daylight intensity at a users' location is realized by the option to dim the windows with a shading factor. Based on the users' requirements for a minimal and desired level of illumination, the proposed optimization problems can be solved by implementing different optimization algorithms. The obtained solutions are able to give instructions to a smart LED system to manage and control system parameters (LEDs dimming levels, semi-angles of the half illuminance, orientation of LEDs, the shading factor) in order to design total illumination, which ensures minimal energy consumption and users' satisfaction related to illuminance requirements.

High-efficiency (over 33 %) indoor organic photovoltaics with band-aligned and defect-suppressed interlayers

In recent years, the emergence of the Internet of Things (IoT) has led to growing interest in the use of organic-based artificial light cells (OALCs; indoor organic photovoltaics) to harvest ambient light energy. This study employs atomic layer deposition (ALD)-processed vanadium oxide (V2O5) hole-transport-layers (HTLs) in non-fullerene acceptor-based OALCs to achieve record power conversion efficiency (PCE) exceeding 33 % under a light-emitting diode lamp (19500 lx; light intensity IL = 4.5 mW/cm2). The material most widely used for HTLs is poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). OALCs with ALD-processed V2O5 HTLs substantially outperform those with PEDOT:PSS HTLs because they have superior hole selectivity, excellent electron-blocking, a smaller interfacial area, and substantially enhanced step coverage which significantly suppresses charge recombination. Moreover, the proposed V2O5-based OALCs have diffusion-free characteristics into the photoactive region and demonstrate excellent performance stability, maintaining a PCE of 92 % after 1000 h under ambient conditions. The results provide insights that enable simultaneous improvements in the efficiency and ambient stability of OALCs for low-powered IoT applications.

The Combination of Monochromatic LEDs and Elicitation with Stressors Enhances the Accumulation of Glucosinolates in Mustard Sprouts with Species-Dependency.

This work studies the enhancement of glucosinolates (GSLs) in mustard sprouts as health promoters. Sprouts of Sinapis alba, Brassica nigra, and B. carinata were grown under broad-spectrum, monochromatic blue or red light-emitting diode (LED) lamps, irrigated with 0-100 mM sodium chloride (NaCl), and sprayed with 0-250 µM methyl jasmonate (MeJA) as elicitor. The use of LEDs did not result in increased sprout biomass in any case. The effect of the applied treatments on the GSLs depended on the species and were restricted to Brassica spp. The red LEDs produced an overall increase in GSLs over 500% in B. carinata (from 12 to 81 mg 100 g-1 F.W.), compared to the white broad-spectrum lights, although the highest increase in content was obtained in treated sprouts with 250 µM MeJA (104 an 105 mg 101 g-1 F.W., under the red and blue LEDs, respectively). The combination of blue LEDs, 100 mM NaCl, and 250 µM MeJA enhanced the levels of GLSs in B. nigra to the maximum (81 mg 100 g-1 F.W.). Overall, these results indicate that by modifying the growing conditions for a given sprout, enhancement in the accumulation of GSLs as health promoters is possible. The use of these treatments is a sustainable alternative to genetic modification when looking for bioactive-enriched foods, delivering natural plant foods rich in bioactive ingredients (e.g., glucosinolates). Nevertheless, the response to the treatments varies among species, indicating that treatments will require adjustment across sprouts. Further research continues with producing cruciferous sprouts to obtain GSL-enriched formulas for further studying the effects of their bioavailability and bioactivity on health-promotion.

Multi-Material Additively Manufactured Magnetoelectric Architectures with a Structure-Dependent Mechanical-to-Electrical Conversion Capability.

Multi-material additive manufacturing has become a promising trend in fabricating advanced functional architectures due to its controllable design of diverse material species and novel structures. It remains challenging to endow the multi-material components with a mechanical-to-electrical conversion capability. This study reports on multi-material selectively laser sintered magnetoelectric architectures that can convert mechanical energy to electricity in a structure-dependent manner. The principal aim is to establish a relationship between the electrical output and the printed structures by fabricating a series of porous architectures with diverse structural parameters. The findings show that the output voltage increases with the decrease of the elastic modulus and the increase of the magnetic height, which has been analyzed by numerical simulation. Owing to the mechanical-to-electrical conversion capability, a pair of multi-material printed sneakers with the functionalities of power generation and gait analysis has been prepared. The voltage output reaches as high as ≈2 V, which can lighten a light-emitting diode lamp when a user is running. The described solution in this work has offered an exploration framework for the design, fabrication, and application prospects of multi-material additively manufactured architectures.

Konutsal Yüklerin Parametre ve Güç Tüketimi Tahmini

With the development of technology, the behavior of electrical devices has also changed. This makes it clear that the development of the load model and the correct identification of the devices are necessary. This study presents the development of the load model of residential loads such as incandescent lamp, Light Emitting Diode (LED) lamp, Liquid Crystal Monitor (LCD) and vacuum cleaner, and experimentally determining the coefficients of the polynomial load model and the exponential load model. Since the measurement parameters are easy to use and economical, PZEM-004T module was transferred to Excel with Arduino Uno and the coefficients and voltage reduction ratio of these load models were calculated in Matlab. It has been determined that both load models are suitable for the incandescent lamp and the vacuum cleaner. Estimated power consumption based on polynomial load model coefficients and actual power consumption results are obtained. According to these results, the estimated power in the incandescent lamp and vacuum cleaner is below the actual power; In the LED lamp and LCD monitor, the estimated power was found to be above the actual power.

LED Lighting Effects on Plant Growth and Quality of Pyrus communis L. Propagated In Vitro

Fluorescent lights are typically used as light source in indoor horticultural production, including micropropagation. However, light emitting diodes (LEDs) have been recently used for plant growth under controlled environment. Major advantage of LEDs is wavelength specificity, that allows to adequately adjust the spectra according to plant needs. The possibility of using LED as primary light source for the micropropagation of Pyrus communis L. has been investigated in this work. It was proceeded to the optimization of a protocol of micropropagation using a LED lamp as the primary light source inside of the growth chamber with specific wavelengths, to reduce energy consumption and increase the quality of the micro propagated plants. Explants were maintained in a growth chamber and exposed to three different continuous spectrum LED lamps (AP67, NS1, G2) as a primary light source and fluorescent lamps (control) for 4 weeks. At the end of four weeks period, it was proceeded to the morphometric and biochemical analysis. Shoot and leaf growths were more influenced by LED lamps as compared to fluorescent lamps (control) in both cultivars. The results showed that the shoots of William and San Giovanni cultivars showed significant differences in morphological and physiological traits, as well as in chlorophyll, carotenoid, and MDA contents. Highest number of neo-formed shoots and nodes were observed in the plantlets of cv William under AP67 LED followed by NS1 and G2 LED lights respectively as compared to the white light (control), whereas same trend was observed in cv San Giovanni under AP67 LED, but it showed higher shoots and node numbers under control LED lamps as compared to both NS1 and G2. The photosynthetic pigments were significantly decreased in leaves of both cultivars when grown under LEDs as compared to the control fluorescent lamps. Moreover, the AP67 LED light had also significant effects on the protein and MDA contents in the leaves of both cultivars in comparison to all other treatments. This work underlines the importance of the modulation of light sources in relation with different species and varieties, allowing optimizing the proliferation phase and the efficiency of Pyrus communis L. micropropagation protocol. Moreover, this protocol can be improved with further studies to examine the response of the plantlets to the ex-vitro acclimatization because the possibility of using LED light for the micropropagation of pear can be considered as a valuable alternative for its ecologically sustainable production.

Enhanced biomass growth of lactobacillus acidophilus with CdS-NPs under visible light irradiation: Semi-artificial biohybrid system

The bacterial biomass growth in a semi-artificial biohybrid system composed of cadmium sulfide nanoparticles (as a light-harvesting semiconductor) and Lactobacillus acidophilus (as the non-pathogenic electron acceptor bacterium) was investigated. The photo-induced electrons generated from cadmium sulfide nanoparticles within the culture medium efficiently enhanced the biomass growth (about 1.15-fold) and indicated a significant difference (P-value = 0.003 (<0.05)) after 48 h of incubation at 37 °C under white light-emitting diode lamp (12 W) compared to the dark control (i.e. culture grown without nanoparticles and light exposure). Scanning electron microscopy indicated the well-distributed spherical nanoparticles on the smooth surface of the bacterium. Energy-dispersive X-ray spectroscopy revealed the presence of nanoparticles on the bacterium cell surface. The findings of this study revealed that integrating cadmium sulfide nanoparticles with Lactobacillus acidophilus under visible light irradiation had a positive effect on bacterium growth.

Hybrid asset localization using light fidelity and Bluetooth Low Energy.

Recently, there has been increasing interest in the field of indoor localization. This field of research can facilitate building and asset management. Although there are different technologies that can be used for localization, there are many limitations that need to be improved, and therefore there is a need to explore new technologies and alternatives that can improve indoor localization. It has been proven that visible light can be used to transfer data. A German physicist, Harald Haas, introduced the term “Li-Fi”, which stands for “light fidelity”, as a new technology that uses light as a medium to deliver data. Accordingly, in this study, we have proposed a hybrid asset localization system using Li-Fi and Bluetooth Low Energy (BLE). This system utilizes light-emitting diodes (LEDs) and BLE tags to detect the locations of assets in a smart building with the support of crowdsourcing technology. The system can make the management, maintenance, and localization process of equipment inside the buildings more easier. To achieve the required, the paper provides a comparison between different applications that have been developed for indoor localization using Li-Fi technology in order to highlight the limitations that need more improvement. The proposed system consists of a web-based administrator panel that allows the administrator to manage maps, assets, tags, LED lamps, and maintenance requests, as well as a mobile application that enables the user to locate, search and view asset information. In addition, the mobile application performs the process of crowdsourcing to update the assets’ locations. We experimentally explore the system’s functionalities and the results show that the system can accurately localize assets, and can detect Li-Fi signals from 55 lx and above within a range of 1.5 m. In addition, the BLE stickers can be detected up to 7 meters away, however, the crowdsourcing process to update the asset location is performed if the distance between the mobile application and the asset is less than or equal 1 m which gives accurate results.

Integrated PV–BESS-Fed High Gain Converter for an LED Lighting System in a Commercial Building

The demand for electricity is rapidly growing and renewable energy sources such as solar, wind and tidal energy can compensate the demand to a substantial level. Among these, solar energy is abundant, scalable and is cheaper. The generated energy can be used in an efficient way if the DC output is directly supplied to the load instead of converting it to AC. Every electrical system is capable of operating in DC and, for example, energy efficient Light Emitting Diode (LED) lights have become popular as they provides more lumens with less power consumption and also can be directly operated from DC. LED lighting system in large commercial buildings has irradiance levels which vary sigificantly during operation. Extracting maximum power from the energy system and maintaining constant voltage output at different loads is another challenge. This paper proposes a solar Photo Voltaic (PV)-based energy system including Battery Energy Storage System (BESS) for supplying LED lamps to a commercial building through a modified high gain Luo converter. The Perturb and Observe control algorithm has been used for maximum power extraction from a PV cell whereas PI (Proportional Integral) controllers maintain constant output voltage from PV–BESS against different irradiance levels. To supply the desired voltages to the LED lighting system, a modified high gain Luo converter is designed. To make the output voltage constant at different load currents, PI and Sliding Mode Controllers (SMC) are designed with the help of the state-space average model. It is found that the sliding mode controller outperforms the PI controller in terms of behavior in the transient period and tracking capability. The system is simulated using MATLAB/Simulink®. The Sliding Mode Controller has a 95% less transient period and is 75% faster in tracking capability when compared to other controllers. The system could be incorporated with the PV source to obtain green energy.

A pH-Stable TbIII-Based Metal-Organic Framework as a Turn-On and Blue-Shift Fluorescence Sensor toward Benzaldehyde and Salicylaldehyde in Aqueous Solution.

A new polydentate tetracarboxylic acid with a benzothiadiazole unit (4',4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid), H4BTDBA) has been used to prepare a pH-stable three-dimensional TbIII-based metal-organic framework (MOF) with the formula {[(CH3)2NH2]0.7[Tb2(BTDBA)1.5(lac)0.7(H2O)2]·solvents}n (Hlac = lactic acid, JXUST-19). JXUST-19 exhibits a new (4,4,12)-connected topology based on tetranuclear [Tb4] clusters. JXUST-19 can remain stable when soaked in water for at least 1 week and in aqueous solutions with various pH values (2-12) for 24 h. Fluorescence study indicates JXUST-19 can be employed as a rare turn-on and blue-shift MOF sensor toward benzaldehyde (BZ) and salicylaldehyde (SA). To date, JXUST-19 represents the first TbIII-based turn-on MOF sensor toward salicylaldehyde in aqueous solution, and the fluorescence enhancement and naked-eye detection of BZ have been rarely reported. In addition, JXUST-19 based fluorescent test papers, light-emitting diode lamp beads, and portable composite films were developed to realize naked-eye detection of BZ and SA, which has great potential in practical applications.

Alteration in Light Spectra Causes Opposite Responses in Volatile Phenylpropanoids and Terpenoids Compared with Phenolic Acids in Sweet Basil (Ocimum basilicum) Leaves.

Basil (Ocimum basilicum, cv. Dolly) grew under three different light spectra (A, B, and C) created by light-emitting diode lamps. The proportions of UV-A, blue, and green-yellow wavelengths decreased linearly from A to C, and the proportions of red and far-red wavelengths increased from A to C. Photosynthetic photon flux density was 300 μmol m–2 s–1 in all spectra. The spectrum C plants had highest concentrations of phenolic acids (main compounds: rosmarinic acid and cichoric acid), lowest concentrations and emissions of phenylpropanoid eugenol and terpenoids (main compounds: linalool and 1,8-cineole), highest dry weight, and lowest water content. Conversely, spectra A and B caused higher terpenoid and eugenol concentrations and emissions and lower concentrations of phenolic acids. High density of peltate glandular trichomes explained high terpenoid and eugenol concentrations and emissions. Basil growth and secondary compounds affecting aroma and taste can be modified by altering light spectra; however, increasing terpenoids and phenylpropanoids decreases phenolic acids and growth and vice versa.

Power impact and electromagnetic disturbances of different lighting modes from spot LED lamp

Light-emitting diode (LED) lamp has been widely used in recent years for lighting systems due to its environmental friendliness, long life, low power consumption and high efficiency. However, LED lamps are sources of harmonic pollution due to AC/DC conversion by rectifier diodes which results in poor power quality. LED lamps research focuses on improving the power factor (PF) and reducing current harmonics.In this article, we present the study of the harmonics of the current generated by two Spot-type LED lamps of the same brand and of different power. We took the following harmonics measurement cases: 6 W and 12 W lamps, the two lamps in parallel, for the different lighting modes, we need to make measurements for the three lighting modes: white lighting, colored lighting and mixed lighting between white and colored. Then, the electromagnetic disturbances conducted in common mode and in differential mode, using the Line Impedance Stabilization Network (LISN), were determined.

Use of Eco-Friendly UV-C LEDs for Indoor Environment Sanitization: A Narrative Review

Background: The current COVID-19 pandemic has demonstrated the enormous importance of maintaining good hygienic conditions in everyday indoor environments for the prevention of infectious diseases. This includes sanitization methods capable of significantly reducing the microbial load in the air and on surfaces. However, in line with the ecological transition, alternative systems for environmental sanitization with reduced environmental impact are urgently needed. The photocatalytic reaction using UV-C light-emitting diode (UV-C LED) lamps with short wavelengths, especially in the range of 200–280 nanometers (nm), can significantly reduce the microbial load, safeguarding the environment thanks to reduced energy consumption. The objective of this review is to describe the latest innovations in the use of UV-C LED technology in the sanitization of indoor environments, reporting the fundamental principles on which its activity relies. Methods: Two databases (PubMed, Web of Science), were searched, following PRISMA guidelines. Results: A total of 1348 publications were identified, of which 379 were assessed in detail and, of these, 16 were included in the review. Conclusions: This literature review highlighted that UV-C LEDs irradiation represents a valid, eco-sustainable sanitization method that could be exploited as an alternative to chemical compounds to contain indoor microbiological pollution in living and working environments.

Fostering Energy Efficiency Through Street Lighting System Improvement: A Case Study of City-Level in Indonesia

Street lighting can be considered the main energy consumer and greenhouse gas emitter at Indonesia's city level. In addition, public street lighting systems throughout Indonesia still use inefficient technologies, resulting in a significant portion of a municipality’s operating expenditure. We conduct techno-economy analysis and formulate financing mechanisms to support energy efficiency improvements on street lighting systems. In doing so, a pilot case based on a survey in one of the provincial capitals in Kalimantan is performed. From the survey, it is found that around half of the street lighting systems in the observed city are unmetered, dominated by CFL (Compact Fluorescent Lamp) lamps. Efficiency through street lighting system improvement can be achieved through, among others, replacement with a highly efficient light-emitting diode (LED) lamp, power meters installation and the replacement of high-efficiency armatures. Our analysis shows that energy consumption reduction potential from street light system improvements can reach 69% from existing conditions. In the showcase, it can save 9,466,465 kWh, equal to energy costs of IDR 13,676,202,724 and a 7,667-ton emission reduction. From the analysis, we also delivered a financial scheme for the project that incorporated local government and special mission vehicles under the coordination of the Ministry of Finance. Having great potential, a financing support mechanism can become a reference to another local government with a limited budget constraint. These findings can also provide policymakers with important inputs while improving street lighting systems as a key service provided by local and municipal governments.

Cowpea speed breeding using regulated growth chamber conditions and seeds of oven-dried immature pods potentially accommodates eight generations per year

BackgroundCowpea is a dryland crop with potential to improve food security in sub-Saharan Africa, where it is mostly produced and consumed. Contemporary plant improvement technologies, including genome editing, marker-assisted selection, and optimized transformation protocols, are being deployed to improve cowpea characteristics. Integrating speed breeding with these technologies would accelerate genetic gain in cowpea breeding. There are established speed breeding protocols for other important legumes, such as soybean, peanut, and chickpea, but none has been previously reported for cowpea.ResultsWith the aid of regulated growth conditions in two different chamber types, as well as the cultivation of new plant generations from seeds of oven-dried immature pods, we developed and validated, for the first time, an efficient speed breeding protocol that accommodates approximately seven to eight breeding generations per year for 3 cowpea genotypes. The 3 cowpea genotypes were evaluated under controlled growth conditions in light-emitting diode and metal halide lamp chambers to determine the effect of CO2 supplementation on flowering and maturation durations, optimum conditions for plant growth, cross pollination, and pod development. Elevated CO2 concentration had no influence on either flowering time or pod development. Adequate temperature, relative humidity and light intensity improved plant development and the rate of successful hand pollination, and cultivating seeds of 11-day-old immature pods oven-dried at 39 °C for 2 days resulted in at least a 62% reduction in the time between pollination and sowing of the next plant generation. The plants cultivated from seeds of the oven-dried immature pods showed no defect at any stage of development.ConclusionsUsing the speed breeding protocol developed in this study, cowpea breeding cycles can be increased from the traditional one cycle per year in the field to as many as 8 generations per year in regulated growth chamber conditions. This protocol has no special technical requirements; hence, it can be implemented in any standard growth chamber. This would fast-track development, testing, validation, and utilization of improved cowpea cultivars.

Effect of LED lights on the in vitro growth of Pinus pseudostrobus Lindl., plants

Pinus pseudostrobus Lindl. is a species endemic to Mexico and is widely used in reforestation programmes, as it is highly adapted to poor, shallow, limestone soils and has high commercial importance. However, it is necessary to preserve this genetic material since it is in trouble due to high rates of deforestation, land use change, and forest fires, so it is necessary to have effective strategies to obtain good quality seedlings. Due to the properties of LED (light emitting diode) lamps used for illumination in the production of in vitro plants, the effects of two different lighting systems (LED and fluorescent) on an in vitro culture were analysed for the morphological characteristics of the growth and photosynthetic pigment content in P. pseudostrobus seedlings. The length and root size of the seedlings were affected by the type of illumination, where a red LED light was the most effective at 30 days of evaluation. However, a blue LED light was equally effective as a red LED light at 60 days of seedling development. On the other hand, the fluorescent light was better in terms of the number of needles in the first stage, but we found the blue LED light to be better in the second stage. For the photosynthetic pigment content, the highest values were found with the blue LED light. The results showed that the LED lighting system favours the growth, development, and photosynthetic pigment content of the species under study.

The Effect of LED and HPS Assimilation Lighting on Leaf Anatomy, Chlorophyll and Carotenoid Autofluorescence Signals, and Some Physiological and Chemical Leaf Traits Related to the Productivity of Cucumber (Cucumis sativus L.) in High-Wire Cultivation

Supplemental lighting with light-emitting diode (LED) lamps and/or high-pressure sodium (HPS) lamps was applied to increase the activity of the photosynthetic apparatus and thus productivity of greenhouse cucumber (Cucumis sativus L.) in a high-wire growing system. The colocalisation of the chlorophyll of PSII (located mainly in grana) and carotenoid fluorescence signals in chloroplasts of cucumber leaves was studied under confocal microscopy. Leaf anatomy and some chemical quality traits (dry matter, chlorophyll, carotenoids, total soluble solids, total sugars and nitrate reductase activity) as well as selected chlorophyll fluorescence parameters were also investigated and subjected to the multidimensional principal component analysis together with the data on fruit yield. Under LED lighting, a lower correlation between the occurrence of chlorophyll and carotenoid fluorescence signals was observed, especially in older (lower-located) leaves, which may have resulted from changes in the distribution of carotenoids within chloroplasts and/or relative concentrations of chlorophyll and carotenoids. Compared to toplighting with HPS lamps, most commonly used in commercial greenhouse cucumber production, the application of LED interlighting, especially in combination with LED toplighting, led to the increase in chlorophyll and carotenoid content and photosynthetic performance index in older leaves, which was related to the increased cucumber productivity.

Energy consumption, CO2 emissions and electricity costs of lighting for commercial buildings in Southeast Asia

Building energy intensity (BEI) has been used to assess a building’s overall energy performance. However, the energy performance, CO2 footprint and electricity costs due to lighting in buildings are currently required to assist relevant authorities to develop, revise and implement energy-efficient lighting policies that are effective and acceptable for the country. This work presents an estimation approach for lighting in commercial buildings in Southeast Asia and its decarbonisation pathway for benchmarking. Application of this approach to a selected library in Brunei Darussalam showed that an energy-efficient light-emitting diode (LED) lighting system would make the building greener. We projected reductions in lighting energy consumption by 6.7 times (3.98 kWh/m2/year), its associated CO2 emissions by 8 times (0.59 kg CO2/m2/year) and electricity costs by 8.7 times (B$7.07/m2/year) by 2050 if existing lamps in the library are retrofitted with LED lamps.