Lighting Energy Conservation Research Articles

Assessing opportunities for enhanced lighting energy conservation via occupancy and daylight monitoring

Efficient energy utilization in buildings is crucial for sustainability. This work proposes an intelligent system that leverages computer vision techniques and CCTV images to assess indoor lighting energy usage based on occupancy, artificial lighting, and daylight conditions. Object detection models - You Only Look Once (YOLO) version 3 (v3) and v8 are employed to detect people, lights, and windows, achieving promising accuracies of 94.9 ​%, 73.3 ​%, and 98.7 ​%, respectively. The system categorizes scenarios as energy-efficient, wasteful, or neutral by integrating these outputs, highlighting opportunities for improving efficiency by harmonizing lighting infrastructure with occupancy and daylight exposure. Performance analyses, including training and validation metrics, are presented. This study demonstrates the potential of computer vision and AI for optimizing energy utilization, enabling sustainable building operation and promoting energy-positive occupant behaviors through sensor-driven methodologies.

Drought-Stressed Apple Tree Grafted onto Different Rootstocks in a Coastal Sandy Soil: Link between Fast Chlorophyll a Fluorescence and Production Yield

Domesticated apple is a drought-sensitive species that spread from continental to Mediterranean temperate regions, where it can particularly experience prolonged water stress. One strategy to improve drought resistance in apple is engrafting on selected rootstocks. This study explores the potential of fast chlorophyll a fluorescence for the comparison of rootstock sensitivity to drought, looking for significant correlations with fruit productivity. The experiment was conducted in a field located in the coastal Po River Plain, Northern Italy, characterized by a loamy sandy soil, particularly prone to drought (86% sand). Mature plants of apple cv. Superchief® Sandidge engrafted on three different rootstocks (CIVP21pbr, MM106, M26) were monitored throughout the summer of 2021 and compared between irrigated and non-irrigated parcels, and at the end of the season, fruit production was evaluated. Despite soil water tension only reaching −13 kPa, the non-irrigated plants experienced a small but consistent loss of Photosystem II (PSII) activity and a lesser capacity of light energy conservation in the photosynthetic electron transport chain. The fruit weight correlated with PSII photochemical indexes recorded during early drought, particularly FV/FM and PIABS; a correlation emerged between fruit number per plant and median values of electron transport parameters, including PITOT. Although all rootstocks underwent a 40% loss of productivity, the fluorescence parameters revealed a graded susceptibility to drought, M26 > CIVP21pbr > MM106, which matched well with the plant vigour. The least drought-sensitive MM106 produced less numerous but heavier fruits than the other two rootstocks.

How to resolve the contradiction between driving safety and lighting energy conservation in a highway tunnel? − An experiment on linear guiding system

High rates of traffic accidents and lighting energy consumption are significant problems in highway tunnels. To address these problems, this study proposes a linear guiding system that uses line-shaped visual guiding facilities to improve the local luminance and contrast, and outlines the tunnel contour and road alignment. In addition, the principle, function, setting method, and composition of the linear guiding system are discussed. Using the existing highway tunnels as prototypes, we built simulation scenarios with different luminance and conducted driving simulation experiments and questionnaire surveys. We analysed the human factor demands of tunnel driving, studied the change rule of various human factor indicators under different luminance levels, and comprehensively evaluated the impact of linear guiding system on driving safety from multiple perspectives of the driver’s vision, psychology, and behaviour. We introduce the concept of equivalent luminance, quantify the impact of linear guiding system on the driver, and explore the role of linear guiding system in energy conservation. The results showed that the linear guiding system has a positive effect on driver vision, psychology, and behaviour, particularly in low-luminance environments. A linear guiding system can optimise a driver’s visual reference frame, enhance driver visual perception in a tunnel environment, and alleviate driver tension. It helps drivers to accurately perceive their own spatial position and speed, providing a good sense of position, speed, and comfort. A 2.3 cd/m2 luminance highway tunnel with a linear guiding system is equivalent to a 4 cd/m2 luminance traditional tunnel. For highway tunnels with luminance values of 4, 5, 6, and 7 cd/m2, the equivalent luminance values of the linear guiding system are 1.7, 1.8, 1.8, and 2.1 cd/m2 respectively, which can reduce the energy consumption by 30–42 %.

Growth, photosynthesis and antioxidant enzyme modulations in broccoli (Brassica oleracea L. var. italica) under salinity stress

Soil salinity is one of the major concerns that pose serious threats to vegetables and other crops worldwide. The present study was carried out to identify morphological, physiological and biochemical markers that broccoli plant may use as adaptive mechanisms to cope with high NaCl stress. Broccoli plants were grown in a pot culture and exposed to NaCl salinity stress for six weeks. Five levels of NaCl; 0, 20, 40, 60, and 80 mmol L − 1 were established using saline irrigation water. Increased soil salinity led to the increased Na+ and Cl– accumulation which inhibited Ca+, K+, Mg2+, NO3–, total P and PO43– concentrations both in leaves and roots. Moreover, increased NaCl salinity decreased the plant leaf area, shoot length, root length, and shoot and root dry weights, whereas enhanced the antioxidant enzymatic activities like superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Leaf chlorophyll in the form of light energy conservation rate (Fv/Fm) and coefficients of photochemical quenching (qP) and (qL) were significantly affected by increasing the salinity levels. Likewise, NaCl salinity negatively affected the linear electron flow (LEF) and the activity of photosystem-II. Non-photochemical quenching (NPQt) in all stress treatments was significantly improved as compared to the control. In general, 60 mmol L − 1 NaCl level was considered as a threshold for broccoli cultivation under saline irrigation. In conclusion, salt stress primarily controlled the leaf photosynthetic machinery, stimulated redox homeostasis and enhanced the activities of antioxidant enzymes, which enabled broccoli plants to tolerate medium level of NaCl stress.

Assessment of control strategy of adaptive façades for heating, cooling, lighting energy conservation and glare prevention

A movable shading device installed on an adaptive façade is able to change the positions of the shades according to the various control objectives (i.e. daylighting, thermal comfort, glare, energy, etc.) of the occupant. Since the key variables and the control method may change according to the control objectives, it is important to determine the hourly states of the shades in consideration of all of these factors. This study proposes a multi-purposes control strategy of adaptive facades for heating, cooling, lighting energy and glare. To depict the movements of the movable shading devices, the operable range is represented by an n number of fixed shade states having constant intervals. The control strategy entails deriving allowable shade states for glare prevention and energy conservation independently and then deriving the intersection range between the two shade state ranges. A case study was performed to verify the changes in hourly shade states and the energy performance of the envelope obtained by applying the proposed control strategy to an adaptive façade having a movable folding type shading device. The results of the case study show that hourly shade states were determined to satisfy the objectives of glare prevention and energy conservation simultaneously based on weather conditions and indoor requirement settings. From the case study, it can be seen that the proposed method can block the entry of direct solar radiation by lowering the unshaded fraction according to whether or not there would be discomfort glare while increasing the view factor in certain sections to promote the entry of diffuse solar radiation into the indoor space during the cooling and heating periods. The results of the case study also show that there can be large differences in the heating, cooling, and lighting energy performance of the building envelope for each orientation depending on the order of priority given to the objectives of the shading control, i.e. the objective of energy conservation only and the objective of simultaneous glare prevention and energy conservation. However, it was possible to effectively reduce the differences in energy proportions by adopting translucent shades.

Intelligent control and energy saving evaluation of highway tunnel lighting: Based on three-dimensional simulation and long short-term memory optimization algorithm

Traditional tunnel lighting luminance is calculated based on the designed hourly traffic volume and designed speed. This approach first determined the entrance section reduction factor and middle section’s luminance through the look-up table method, then calculated each section’s luminance in proportion. Since the designed value is often higher than the actual traffic flow value, and the calculated brightness value is so high which might lead to tunnel energy consumption. What’s more, the designed value in this method is the piecewise discrete value, which does not meet the requirement of continuous dimming for LED lighting. In this case, under the premise of satisfying operation safety, how to carry out continuous intelligent energy saving control research and energy saving evaluation based on actual traffic value is an urgent problem to be solved in tunnel lighting. This paper first proposed a luminance calculation model for each lighting section which can realize continuous dimming as needed. Using the least squares method fitting the reduction coefficient and the luminance of the middle section to solve the luminance of the entrance and middle sections under the condition of any speed and traffic flow, and realizing the continuous optimization of the luminance calculation. Second, in terms of the shortcomings of the traditional graded dimmer control, this paper offered a highway tunnel lighting intelligent control algorithm with traffic flow, speed and luminance out of the tunnel as the input matrix, which meets the requirement of LSTM (Long Short-Term Memory) neural networks, tunnel lighting characteristics and tunnel lighting section. Considering the objective function of optimization problem in LSTM, three gradient descent methods were introduced to optimize the model respectively. Third, this paper adopted equal proportion to arrange lamps and light distribution, and developed a tunnel lighting simulation environment based on DIALux to meet the energy conservation assessment requirements in operating tunnels. Roadway luminance and its total uniformity are selected as energy saving evaluation indexes. Finally, we established a three-dimensional tunnel model with the real environment of Jinding Lake 2# tunnel, then conducted simulations and experimental verifications of the intelligent control algorithm under sunny and cloudy weather conditions, and verified the performance of the intelligent lighting control algorithm under the three optimizers. The result of energy conservation evaluations shows that compared with traditional lighting design, the tunnel lighting energy conservation algorithm can save 23.61% of energy in sunny days and 31.40% in cloudy days.

Na+-Translocating Ferredoxin:NAD+ Oxidoreductase Is a Component of Photosynthetic Electron Transport Chain in Green Sulfur Bacteria.

Genomes of photoautotrophic organisms containing type I photosynthetic reaction center were searched for the rnf genes encoding Na+-translocating ferredoxin:NAD+ oxidoreductase (RNF). These genes were absent in heliobacteria, cyanobacteria, algae, and plants; however, genomes of many green sulfur bacteria (especially marine ones) were found to contain the full rnf operon. Analysis of RNA isolated from the marine green sulfur bacterium Chlorobium phaeovibrioides revealed a high level of rnf expression. It was found that the activity of Na+-dependent flavodoxin:NAD+ oxidoreductase detected in the membrane fraction of Chl. phaeovibrioides was absent in the membrane fraction of the freshwater green sulfur bacterium Chlorobaculum limnaeum, which is closely related to Chl. phaeovibrioides but whose genome lacks the rnf genes. Illumination of the membrane fraction of Chl. phaeovibrioides but not of Cba. limnaeum resulted in the light-induced NAD+ reduction. Based on the obtained data, we concluded that in some green sulfur bacteria, RNF may be involved in the NADH formation that should increase the efficiency of light energy conservation in these microorganisms and can serve as the first example of the use of Na+ energetics in photosynthetic electron transport chains.

Proposal for Light Shelf System that Applies Biomimicry for Lighting Energy Conservation

Proposal for Light Shelf System that Applies Biomimicry for Lighting Energy Conservation

Animal species identification in parchments by light

Recently, historical and conservation studies have attached an increasing importance to investigating the materials used in historic documents. In particular, the identification of the animal species from which parchments are made is of high importance and is currently performed by either genetic or proteomic methods. Here, we introduce an innovative, non-invasive optical method for identifying animal species based on light-parchment interaction. The method relies on conservation of light energy through reflection, transmission and absorption from the sample, as well as on statistical processing of the collected optical data. Measurements are performed from ultraviolet (UV) to near-infrared (NIR) spectral ranges by a standard spectrophotometer and data are processed by Principal Component Analysis (PCA). PCA data from modern parchments, made of sheep, calf and goat skins, are used as a database for PCA analysis of historical parchments. Using only the first two principal components (PCs), the method confirmed visual diagnostics about parchment appearance and aging, and was able to recognise the origin species of historical parchment of among database clusters. Furthermore, taking into account the whole set of PCs, species identification was achieved, with all results matching perfectly their proteomic counterparts used for method assessment. The validated method compares favourably with genetic and proteomic methods used for the same purpose. In addition to animals’ proteomic and genetic signatures, a unique “optical fingerprint” of the parchments’ origin species is revealed here. This new method is non-invasive, straightforward to implement, potentially cheap and accessible to scholars and conservators, with minimal training. In the context of cultural heritage, the method could help solving questions related to parchment production and, more generally, medieval writing production.

Self-luminous wood composite for both thermal and light energy storage

High efficient energy storage devices for both thermal energy and light energy are scarce in the development of modern society to reduce energy consumption. In this work, a novel self-luminous wood composite based on phase change materials (PCMs) with superior thermal energy storage and long afterglow luminescence (LAL) materials with excellent light energy storage is reported. The obtained self-luminous wood composites shows high latent heat of fusion (146.7 J g-1), suitable phase change temperature at about 37 ℃, favorable thermal reliability and thermal stability below 105 ℃ with excellent shape-stability. More importantly, the self-luminous wood composites can absorb ultraviolet and visible light from lighting source and natural light, and emit green light in the dark for 11 h. More interesting, the addition of LAL particles can improve the thermal conductivity of self-luminous wood composites. All results demonstrate self-luminous wood composites can store both thermal energy and light energy, and have great potential in applications including furniture, emergency light, storage and building energy conservation.

Integrated design and real-time implementation of an adaptive, predictive light controller

Daylight–electric light integrated schemes encompassing soft computing models have been perceived as a lucrative option for lighting energy conservation. This paper exploits the quintessence of design and real-time implementation of an adaptive predictive control strategy for robust control of a daylight–electric light integrated scheme. To elicit daylight variations, occupancy detection and user preferences an online self-adaptive, predictive control algorithm is structured for real-time control of electric lights and window blinds. The adaptive, predictive model entails integration of an online, adaptive daylight illuminance predictor in conjunction with an electric light intensity control algorithm for interior illuminance regulation and a fuzzy-logic based window blind control algorithm to eliminate glare and solar heat gain. The control algorithm modelled with real-time sensor information administers an online process of identification, prediction and parameter adaptation. The prototype controller is successfully implemented in a test chamber. A real-time user-friendly simulator provides an online visualisation of illuminance performance indicators and control of the process. The anticipated synergetic effects of the online control algorithm validated in the test chamber highlights the benefits of the scheme in terms of glare control, illuminance uniformity and energy efficiency.

Conservation and dissipation of light energy in desiccation-tolerant photoautotrophs, two sides of the same coin

Conservation of light energy in photosynthesis is possible only in hydrated photoautotrophs. It requires complex biochemistry and is limited in capacity. Charge separation in reaction centres of photosystem II initiates energy conservation but opens also the path to photooxidative damage. A main mechanism of photoprotection active in hydrated photoautotrophs is controlled by light. This is achieved by coupling light flux to the protonation of a special thylakoid protein which activates thermal energy dissipation. This mechanism facilitates the simultaneous occurrence of energy conservation and energy dissipation but cannot completely prevent damage by light. Continuous metabolic repair is required to compensate damage. More efficient photoprotection is needed by desiccation-tolerant photoautotrophs. Loss of water during desiccation activates ultra-fast energy dissipation in mosses and lichens. Desiccation-induced energy dissipation neither requires a protonation reaction nor light but photoprotection often increases when light is present during desiccation. Two different mechanisms contribute to photoprotection of desiccated photoautotrophs. One facilitates energy dissipation in the antenna of photosystem II which is faster than energy capture by functional reaction centres. When this is insufficient for full photoprotection, the other one permits energy dissipation in the reaction centres themselves.

Sustainability assessment of low carbon technologies–case study of the building sector in China

In order to meet the goals of GHG reduction and sustainability in industry development, strategies are needed that are reducing GHG emissions without compromising other economic, environmental and social priorities. In this paper, existing low carbon and sustainability requirements and evaluation methods are comparatively analyzed based on an in-depth literature review. Based on this analysis, multi-attributive assessment is selected as the methodological basis of our envisaged assessment framework; modified indicators and classified values are designed accordingly. The building sector in China is analyzed as a case study. Eleven main building energy saving technologies are assessed. The results show that under the sustainability criterion, the priority order of the assessed technologies is as follows: geothermal heat pump; solar thermal; solar PV; air conditioning energy saving; central heating system energy saving; building enclosure; lighting energy conservation; electric water heater energy saving, washing machine energy saving, refrigerator energy saving (these three have equal priority), and cooking appliance energy saving. The GHG and sustainability properties of technologies are discussed by comparing the indicator scores of the two aspects. The designed evaluation method can be used in regional cases if data resources are available; and for other sectors after indicator modification.

Light utilization efficiency in photosynthetic microbial mats

Based on combined microsensor measurements of irradiance, temperature and O(2) , we compared light energy budgets in photosynthetic microbial mats, with a special focus on the efficiency of light energy conservation by photosynthesis. The euphotic zones in the three studied mats differed in their phototrophic community structure, pigment concentrations and thickness. In all mats, < 1% of the absorbed light energy was conserved via photosynthesis at high incident irradiance, while the rest was dissipated as heat. Under light-limiting conditions, the photosynthetic efficiency reached a maximum, which varied among the studied mats between 4.5% and 16.2% and was significantly lower than the theoretical maximum of 27.7%. The maximum efficiency correlated linearly with the light attenuation coefficient and photopigment concentration in the euphotic zone. Higher photosynthetic efficiency was found in mats with a thinner and more densely populated euphotic zone. Microbial mats exhibit a lower photosynthetic efficiency compared with ecosystems with a more open canopy-like organization of photosynthetic elements, where light propagation is not hindered to the same extent by photosynthetically inactive components; such components contributed about 40-80% to light absorption in the investigated microbial mats, which is in a similar range as in oceanic planktonic systems.

Research on the System of Lighting Energy Conservation in Public Places

To response the call of “constructing an economical society” and saving electricity consumption of public places, this paper designs an automatic control system of lumination in public places based on time, lighting intensity and personal distribution etc. It’s in low price that it is equivalent to a manual switch. Moreover, it’s low energy consumption, with steady performance, convenient installation without changing original line.

Conversion and conservation of light energy in a photosynthetic microbial mat ecosystem

Here we present, to the best of our knowledge, the first balanced light energy budget for a benthic microbial mat ecosystem, and show how the budget and the spatial distribution of the local photosynthetic efficiencies within the euphotic zone depend on the absorbed irradiance (J(abs)). Our approach uses microscale measurements of the rates of heat dissipation, gross photosynthesis and light absorption in the system, and a model describing light propagation and conversion in a scattering-absorbing medium. The energy budget was dominated by heat dissipation on the expense of photosynthesis: in light-limiting conditions, 95.5% of the absorbed light energy dissipated as heat and 4.5% was channeled into photosynthesis. This energy disproportionation changed in favor of heat dissipation at increasing irradiance, with >99% of the absorbed light energy being dissipated as heat and <1% used by photosynthesis at J(abs)>700 micromol photon m(-2) s(-1) (>150 J m(-2) s(-1)). Maximum photosynthetic efficiencies varied with depth in the euphotic zone between 0.014-0.047 O(2) per photon. Owing to steep light gradients, photosynthetic efficiencies varied differently with increasing irradiances at different depths in the euphotic zone; for example, at J(abs)>700 micromol photon m(-2) s(-1), they reached around 10% of the maximum values at depths 0-0.3 mm and progressively increased toward 100% below 0.3 mm. This study provides the base for addressing, in much more detail, the photobiology of densely populated photosynthetic systems with intense absorption and scattering. Furthermore, our analysis has promising applications in other areas of photosynthesis research, such as plant biology and biotechnology.

Conservation and dissipation of light energy as complementary processes: homoiohydric and poikilohydric autotrophs

The relationship between photosynthetic energy conservation and thermal dissipation of light energy is considered, with emphasis on organisms which tolerate full desiccation without suffering photo-oxidative damage in strong light. As soon as water becomes available to dry poikilohydric organisms, they resume photosynthetic water oxidation. Only excess light is then thermally dissipated in mosses and chlorolichens by a mechanism depending on the protonation of a thylakoid protein and availability of zeaxanthin. Upon desiccation, another mechanism is activated which requires neither protonation nor zeaxanthin although the zeaxanthin-dependent mechanism of energy dissipation remains active, provided desiccation occurs in the light. Increased thermal energy dissipation under desiccation finds expression in the loss of variable, and in the quenching of, basal chlorophyll fluorescence. Spectroscopical analysis revealed the activity of photosystem II reaction centres in the absence of water. Oxidized beta-carotene (Car+) and reduced chlorophyll (Chl-), perhaps ChlD1 next to P680 within the D1 subunit, accumulates reversibly under very strong illumination. Although recombination between Car+ and Chl- is too slow to contribute significantly to thermal energy dissipation, a much faster reaction such as the recombination between P680+ and the neighbouring Chl- is suggested to form the molecular basis of desiccation-induced energy dissipation in photosystem II reaction centres. Thermal dissipation of absorbed light energy within a picosecond time domain deactivates excited singlet chlorophyll, thereby preventing triplet accumulation and the consequent photo-oxidative damage by singlet oxygen.

소규모 사무공간에서 디밍제어를 이용한 조명에너지 절약에 관한 연구

소규모 사무공간에서 디밍제어를 이용한 조명에너지 절약에 관한 연구

A Little Light Provocation and the New Challenges

Current attitudes to daylighting and electric lighting design need reviewing, revitalizing and redirection. Daylighting design methods involving static concepts such as daylight factor and average or mean skies are criticised. Similarly, consideration of electric lighting design as the means of providing uniform horizontal illuminances and glare checks in satisfaction of code requirements are also criticised as limited. Consider the light sources. Fixed spectrum and fixed light output from electric light luminaires on the one hand, and variable spectrum, variable direction and variable, fluctuating, output from sun and sky on the other hand. This is the contrast to be recognised and incorporated in integration of the two light sources. This is one challenge in lighting design in satisfaction of human needs. Many existing computer programs for lighting calculations do not recognise these realities. Static concepts for daylight are not lighting design, and integration of such programs into energy conservation calculations are quite misleading. New computer programs incorporating variability of daylight as it occurs naturally present a further challenge. The Commission internationale de L’Eclairage (C.I.E) International Daylight Measurement Programme (IDMP) aims to provide the necessary daylighting design data for a new approach to lighting design and energy conservation in lighting. Of course, new computer programs will be developed from this data. For this daylight measurements programme special equipment specifications have been defined and participants must comply with strict standards of data acquisition and reporting. In electric lighting design, new work is required to develop design methods for variability in spatial illuminance, and also to build on earlier work involving vector and scalar illuminances in modelling, and applications of semicylindrical and cylindrical illuminance in a 4-dimensional approach to lighting, where the fourth dimension can be considered to be time, or change, or variety/variability in satisfaction of human needs. With changed attitudes in lighting engineers the problems of daylight and electric light, new windows and people, will provide an exciting challenge for the future.

A Model of the Effect of Interspecies Competition for Light on Dry-Matter Production

A model of the effect of interspecies competition for light on the daily dry-matter production of competing species is developed. It describes the absorption of light by the component species, accounting for their different optical properties. Absorption equations are formulated from the principle of conservation of light energy within a unit-leaf-area-index of canopy, and the integral of absorbed light energy is then used to calculate the rate of dry-matter production of each component species. This model proved useful for the analysis of data from experiments in which New Zealand white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) were grown in mixtures. Application of the model enabled the proportion of incident light energy absorbed by each component to be estimated and unambiguous differentiation between the amount of light energy absorbed and the efficiency of use of the absorbed light energy.