Lighting Energy Consumption Research Articles

Performance Evaluation of External Light Shelves by Applying a Prism Sheet

To address the increased use of lighting energy in the building sector, research on the use of light shelves has been increasing. Previous studies have focused on applying operating techniques to improve daylighting performance, which reduces the economic efficiency of light shelves and the building energy savings. This study proposes the use of prism sheets to improve the performance of light shelves, a concept which was validated by evaluating the performance related to saving building energy and improving indoor light uniformity through a full-scale testbed. This study used an external light shelf with no prism sheet, a window with a prism sheet applied, and a window with both an external light shelf and prism sheet applied as Case 1, Case 2, and Case 3, respectively, and analyzed the illuminance distribution and lighting energy consumption required to maintain the optimal indoor illumination for each case. This study also derived the optimal specifications for each case to save building energy and considered the flow of natural light to analyze the performance evaluation results. The main findings are as follows: (1) the optimal specifications to improve daylighting performance were derived for Case 1, requiring the application of operating techniques; (2) Case 2 was not suitable for saving energy and improving light uniformity when compared to Case 1; and (3) Case 3 was effective in saving building energy. In Case 3, even when the light shelf was fixed at 20° without moving, it saved building energy and improved light uniformity compared to Case 1. However, the prism sheet in Case 3 should be detached during winter to maximize building energy savings.

Retrofit guidelines towards the achievement of net zero energy buildings for office buildings in Brasilia

There is an ongoing, global discussion on the ways to obtain Net Zero Energy Buildings (NZEBs). Nonetheless, little attention was given on the application of NZEBs in warm climates, especially in Brazil. Therefore, the aim of this article is to propose retrofit guidelines that meet a net zero energy target for four-story office buildings in the climactic conditions within Brasilia. Through this research 240 office buildings in the downtown area of the Brazilian capital were morphologically characterized, which served as the basis for the definition of a representative model of the four-story office buildings. The model variations – 69 in total – were tested taking in consideration a combination of building skin variables, following recommendations from the literature, and national energy efficiency standards. Simulations were then carried out in Design Builder and Diva to predict final energy consumption for air-conditioning, lighting, and office equipment, and simultaneously, solar photovoltaic energy production on the building skin of the respective models – on the roof, and on the North, East and West facades in PVSYST. Results showed a 46% reduction of the total final energy consumption in the optimized model. This paper showed that it is possible to achieve the NZEB goal in the up-to-four-story office buildings in the climate zone of Brasilia. Thus, the paper provides what was needed to draft a series of guidelines and strategies to use in the energetic renovation of the building complex, buildings towards the achievement of the NZEB goal in the climate zone of Brasilia. The novelty of this research is to apply the concept of NZEB in existing office buildings in Brasilia.

Light transmitting cement-based material (LTCM) as a green material for building

<p>In recent years, light-transmitting cement-based materials (LTCM) have become important in the construction of green buildings because these reduce energy consumption for lighting. LTCMs were prepared by adding polymeric optical fibers (POFs) in a high strength self-compacting mortar (SCM). SCM was formulated from Portland cement, fine sand and water reducing admixture following the EFNARC criteria. LTCMs with a constant fiber content (5%) and three fiber diameter (0.75, 1 and 1.5 mm) were prepared by casting fresh SCM into a formwork designed ad hoc to keep the fibers fixed and aligned. Light transmitting performance of LTCM was tested by optical power measures. The effects of fiber diameter and distance between sample and detector on the optical power were evaluated. The compressive strength of hardened SCM reached a value of 69 MPa at an age of 28 days, while the LTCMs maintained sufficient strength for structural purposes. LTCMs are suitable to produce precast blocks and wall panels for application in building facades, signage and decorative art.</p>

Sustainable approach to energy rating system for residential buildings

Energy rating system can be considered as a key policy instrument that will assist government to reduce energy consumption. Existing rating systems in the world only considered limited factors related to energy consumption, and to provide more accurate rating system, it is proposed that a more sustainable energy rating system should be developed considering all the criteria. This study was aimed at identifying the existing rating systems, which investigate the existing systems, to identify the parameters required for determining the energy performance of residential buildings, and to develop a model for calculating the energy score for residential buildings in tropical climates, and Sri Lanka was selected for case study. The research followed the concept of sustainable energy which comprise of both energy efficiency and renewable energy. The energy efficiency of a residential building needs to consider the energy efficiency due to building properties and energy efficiency of the occupants. To evaluate the energy efficiency of the building properties, the asset rating method was used where the building is modelled and the energy consumption for thermal comfort and lighting is calculated. When developing the occupancy behaviour rate, the average domestic energy consumption in Sri Lanka was used as a reference, without normalising. For the energy source rate, a sustainability index was used, and based on the percentage of contribution of the energy sources to the final energy use, the final energy source rate was determined.

Energy consumption analysis of glass house using electrochromic window in the subtropical region

PurposeElectrochromic window (ECW) has been gradually applied to building engineering in recent years. However, empirical study of this technology used in green building design is still lacking. This study aims to verify the lighting and energy-saving performance of ECW under a specific geographical environment.Design/methodology/approachThe meditation pavilion of Jinwan new materials research institute in Zhuhai is taken for research object. Three kinds of sun-shading techniques, namely, ECW, Low-E window and ordinary glass window, with same specifications are selected as the building facade structure for simulation. Day lighting analysis, sun-shading performance and annual energy consumption are separately simulated in the same environment by the Autodesk Ecotect Analysis software. The energy-saving performance of ECW is obtained by comparisons.FindingsResult shows that the shading performance of ECW is much better than ordinary window and Low-E window. When ECW is used in the east, west or top lighting interfaces of a building, about 40% of the total solar radiation can be reduced during daytime in summer. Taking the ordinary glass window as a basic reference, ECW can save about 90% of the annual energy consumption of the glass house. ECW can effectively reduce the annual refrigeration energy consumption of buildings in the subtropical region.Practical implicationsReasonable use of ECW in the subtropical region can effectively reduce the annual energy consumption of buildings.Originality/valueIt is a precedent study to analyze the lighting performance and energy consumption of a glass house with ECW. The energy-saving characteristics and beautiful appearance of ECW shall make it a future green building technology.

Multi-objective optimization design for windows and shading configuration considering energy consumption and thermal comfort: A case study for office building in different climatic regions of China

As a large energy-consuming part of the envelope, windows and shading system play a significant role in building savings. Once established in the primary design stage, it is difficult to make changes later, especially for high-rise buildings with large areas of glass. Moreover, strongly influenced by solar radiation, the configuration of windows and shading system conflicts with each other in terms of energy consumption and indoor comfort, the optimal configuration of windows and shading system under different climatic regions has not been well solved at yet. This paper proposes an easy-operation, useful, and efficient multi-objective optimization method, using a smart optimization algorithm NSGA-II in combination with DesignBuilder energy simulation software, especially beneficial for non-programming designers. In this research, a typical high-rise office building with a large area window has been selected as a case study. Building orientation, the configuration of windows and shading system, including materials for each layer of the double-layer window, installation angle and depth of overhangs have been taken into consideration, aiming to minimize the heating, cooling, lighting energy consumption and discomfort hours, and to find the mutual relationship between each other. A set of Pareto solutions can be obtained after optimization, and the most recommended variable parameters of windows and shading system in four cities representing severe cold climate, cold climate, hot summer and cold winter climate, and hot summer and warm winter climate can be identified, respectively. Besides, Pareto optimal solutions can give designers different scheme choices based on preferences, which are of great significance to provide guidance and suggestion for designers in the early design of buildings.

Multi-Objective Analysis of a Fixed Solar Shading System in Different Climatic Areas

This study tackles the analysis of fixed external solar shading systems. The geometry of a building and of the shading system has been parametrically defined and a genetic optimization analysis has been carried out to identify an architectural solution that would allow the increase of energy savings, through a suitable window-to-wall ratio and an accurate design of the shading device. A multi-objective analysis has been performed with the aim of minimizing the energy consumption for space heating, cooling and artificial lighting, while ensuring the visual comfort of the occupants. The main goal of the study is to explore the influence of climatic context on the optimal design of shading devices. The analysis has been performed for three different latitudes across Europe. In all analyzed cases, a reduction of the annual energy consumption could be achieved, up to 42% if the optimal shading configuration is used. Moreover, the possibility of integrating the shading system with photovoltaic (PV) panels has been considered and the electricity production has been estimated.

Prediction of Electricity Consumption using Adaptive Neuro-fuzzy Inference System

The electricity consumption has been increasing day to day Exponentially from the invention of electricity and more Over the production of electricity has been fulfilling for the Current population in the world, Electrical loads and energy consumption forecasting are some of the most important tasks in power system operation and planning. However, in some cases, we need to solve this problem in the absence of reliable and adequate historical data. To develop an accurate prediction model of lighting energy consumption, Therefore by predicting the electricity consumption with various parameters based on usage on different climate conditions. The previous papers produce the prediction of electricity consumption by using different models and different data sets. This paper presents the approach using the Adaptive neuro-fuzzy inference system (ANFIS), it considers the previous data and predict future consumption based on weather parameters. The assessment of this model is from weather data and the electricity consumption data available on the internet, the outcome shows that model is effective.

Design and optimization of a novel electrowetting-driven solar-indoor lighting system

Considering the high level of energy consumption for lighting in commercial buildings, the use of solar energy for daylighting is appealing more interests at both research and industrial levels. This study presents a novel daylighting system working on the principles of electrowetting. It integrates electrowetting-driven liquid prisms with existing optical fiber daylighting systems, which not only facilitates flexible regulation of the lighting power but also allows for recovery of excess sunlight that is not used for daylighting. An improved design is firstly proposed for the liquid prism to simplify the fabrication processes, increase its reliability, and facilitate easier maintenance. Liquid prisms are then fabricated using the proposed design, and different functionalities are demonstrated. Based on the optimized component design, the illumination performance and energy-saving potential of the proposed daylighting system is quantified using long-term climatological data. Under the climatic conditions of Singapore, a stand-alone system with 1 m2 solar collector is able to provide an annual illumination time of more than 2260 h for a 10 m2 office. The energy consumption for driving the prism is found to be negligible compared with the illumination power provided. Additionally, recovery of the excess energy would further improve the illumination time by up to 95%, while the energy cost is reduced by 20%.

The negative impact of skylights on light-irresponsive historical sites within archaeological museums: A case study

Most historical sites in archaeological museums have an inorganic origin. According to the specifications prescribed in CIE 157: 2004, these inorganic collections are light-insensitive and can be preserved in an environment without any light restrictions. Roof skylights are therefore widely used in archaeological museums in China to provide natural lighting and reduce lighting energy consumption. However, many of the historical sites in these archaeological museums are not preserved as well as expected due to their unique soil-air coupled preservation environment and the transmission of sometimes intense sunlight into the relic preservation area. This research takes Chengdu Jiangnan Pavilion Street Site Museum as a case study to evaluate the influence of skylights and direct sunlight on historical sites within archaeological museums. An integrated analysis of the negative impact of skylights on historical sites was implemented by comparing the preservation environment in illuminated and non-illuminated areas. The results show that the light intensity at the illuminated area is more than 100 times at the non-illuminated area, the intense sunlight not only induces severe environmental fluctuations where the maximum daily change in temperature and RH reach 9.7 °C and 24%, respectively, but, under the damp conditions at this site, also accelerates salt accumulation at the site surface and stimulates moss growth. Strong sunlight through a skylight can result in deterioration even of light-insensitive historical sites within archaeological museums, and so skylights in archaeological museums should be rationally designed to avoid sunlight directly hitting the surface of historical sites housed within them.

Controlled Dynamic Search for a Mobile Object with Minimum Cost of Light Energy

We consider the optimal control problem for the spatial motion of a dynamic object in order to search for a moving object that performs simple motion in a rectangular region on a plane. As the optimality criterion, we consider a functional that takes into account the energy consumption of a light source located on the searching object. The object in question is considered to be detected when it reaches the light square with a given illumination. We propose a method for controlling the movement of a searching object, as well as the corresponding law of variation of the electric current in the light source circuit, which ensure the detection of the desired object under a guaranteed search time with minimal light energy consumption.

A prediction model coupling occupant lighting and shading behaviors in private offices

Lighting control in office buildings is driven by occupant's demand for indoor light environment. The control behavior not only has a direct impact on occupants’ visual comfort, but also relates with the building lighting energy consumption. However, due to the effect of glare, lighting control is often associated with shading adjustment. In this regard, this paper proposed a prediction model which can accurately describe the lighting and shading coupling control behavior by fully considering the difference and diversity of occupants. The light environment preferences and the usage habits of lighting and shading system of occupants were firstly investigated and classified by means of questionnaire. Markov model and log-logistic survival model were introduced to quantitatively describe the probability distribution of various shading and lighting control behaviors. On this basis, combined with the indoor workplane illumination prediction model, the behavior of occupant's lighting and shading coupling control can be predicted. By comparing the four models considering or not considering the diversity and coupling effect, it is found that the proposed coupling prediction model shows better performance, the maxium error rate is only 13.04% for the lighting energy consumption prediction.

Research on Lighting and Energy Consumption in Large Space of Railway Station in Hot-Summer and Cold-Winter Zone in China

Based on surveys and tests of railway stations in hot summer and cold winter zone in China, analyzed the status quo of railway station buildings. A performance analysis model of the Zhengzhou East Railway Station waiting hall was established to analyse the effects of scattered skylights and different aspect ratios on the lighting environment and energy consumption characteristics, provided reference for the design of Railway Stations in hot summer and cold winter zone.

Model for Thermal Comfort and Energy Saving Based on Individual Sensation Estimation

In office spaces, the ratio of energy consumption of air conditioning and lighting for maintaining the environment comfort is about 70%. On the other hand, many people claim being dissatisfied with the temperature of the air conditioning. Therefore, there is concern about work efficiency reduction caused by the current air conditioning control. In this research, we propose an automatic control system that improves both energy-saving and thermal comfort of all indoor users by quantifying individual differences in thermal comfort from vital information, on the basis of which the optimal settings of both air conditioning and wearable systems that can directly heat and cool individuals are determined. Various environments were simulated with different room sizes, numbers of users in a room, and heating/cooling conditions. The simulation results demonstrated the efficiency of the proposed system for both energy saving and comfort maximization.

Energy savings and daylighting evaluation of dynamic venetian blinds and lighting through full-scale experimental testing

Commercial buildings consume around 20% of the total energy utilized in the U.S. The use of shading devices in buildings has the potential to reduce building energy consumption while also providing a more desirable indoor environment for building occupants. Similarly, lighting device controls help reduce lighting energy consumption as well as internal loads. However, there is lack of full-scale experimental testing of integrated dynamic shading and lighting controls. This study presents full-scale experimental testing data to quantify these energy and daylighting impacts. Testing was performed utilizing two different control strategies, in three different orientations under three different types of sky conditions. The shading device was also used in conjunction with two different types of glazing. An average of 25.4% cooling energy savings and 48.5% lighting energy savings was achieved. Visual discomfort evaluated using Simplified Daylight Glare Probability was prevented more than 85% of time during occupied hours. Improvement in daylight levels evaluated using Useful Daylight Illuminance was also achieved. Finally, analysis of the relationship between the illuminance level measured at the work plane and a ceiling illuminance sensor is performed to translate the real-world applicability of shading device controls.

Energy saving based lighting system optimization and smart control solutions for rail transportation: Evidence from China

As the natural resources are becoming exhausted, energy consumption by metro systems dominates internal transportation resources in urban areas. The comprehensive exploration of energy improvements in lighting system energy is necessary. To evaluate the energy-saving potential and identify the efficiency improvement opportunities for lighting operations in metro systems, an intelligent energy management system for metro stations is examined through a case study in Nanchang city of China. First, the study explores the main factors influencing the lighting energy consumption of metro systems and analyses the lighting distribution in different station regions. Second, DIALux software is employed to optimize and monitor the best illuminating effect for hall lighting in the selected station. Third, an intelligent model is proposed for the lighting system based on the energy-saving scheme and solution using BECH energy analysis software combined with DIALux software. A thermal model is proposed to verify the energy and load performances. Results show that (1) the proper layout by means of DIALux software, can not only meet the functional demands of lighting but also reduce energy consumption; (2) intelligent lighting control system can improve the lighting energy-saving design, and the lighting control framework is capable of refined control; and (3) based on the performance analyses, the solution with the adopted DALI digital light adjustment is helpful for increasing passengers' comfort and realizing the goals reduction.The novelty is to integrate the lighting energy saving solution with software within an intelligent management and verified its valuable application, it is practical for construction emission control.

A method of partition design for open-plan offices based on daylight performance evaluation

Daylight performance has a considerable effect on occupants' comfort and satisfaction of office buildings. Nowadays, open offices are a common typical plan, in which the workstations are separated via partitions. These partitions completely affect daylight performance due to their height, material, and arrangement. Therefore, the optimum design of partitions is vital to boost the daylight performance. The current paper presents a method in form of a tool for designing and evaluating of partitions based on the main daylight metrics. Considering the climatic and urban situation of the building (in form of epw file, and the shading effect of adjacent buildings), in addition to the office characteristics (office layout, window size, and orientation), the used method changes the above-mentioned parameters of partitions and evaluates the daylight availability, visual comfort, and lighting energy demand, presented in the form of a Grasshopper plugin. The developed tool has been used to define the optimum workstation layout for an office building in Tehran. Results indicate that an increasing panels' reflectivity compensated reduction of the received daylight caused by partitions height incensement. 20% reduction in partitions reflectivity, and 0.2 m increase of partitions’ height, decrease the spatial daylight autonomy daylight by 9.47% and 4.36%, while increasing the artificial lighting energy consumption up to 10.01% and 6.27%, respectively. The presented tool provides an evaluation method of partitions arrangement optimization in open-offices for designers and architects during the design and retrofit procedure.

Energy-maintenance optimization for retrofitted lighting system incorporating luminous flux degradation to enhance visual comfort

Retrofitting existing buildings with energy-efficient lighting systems is an effective way to reduce their lighting energy consumption and improve lighting quality. In a lighting system, the illumination level decreases over time owing to the luminous flux degradation of lights. This degradation may cause visual discomfort if proper maintenance is not carried out. Also, energy savings decrease with the degradation of retrofitted lights. Maintenance of lighting devices requires investments for the purchase and installation of new lamps. Therefore, optimum balance is required between maintenance costs and the performance of the lighting system. This study presents an energy-maintenance optimization model, which takes into account the luminous flux degradation. Luminous flux degradation is modeled based on users’ lighting level requirements. Based on the proposed luminous flux degradation model, the energy-maintenance optimization model is formulated to find the optimal number of lamps to be replaced, maintenance schedules, and brightness dimming level, while taking into account users’ lighting level requirements, maintenance budget, and energy savings. An open-plan office is taken as a case study to illustrate the effectiveness of the proposed optimal energy-maintenance plan. It is found that the optimal energy-maintenance plan yields to 31.27 MWh energy savings in 10 years. Compared to the full maintenance, the optimal maintenance plan developed in this study reduces the total maintenance cost by 30%.

Ensemble Learning Model-Based Test Workbench for the Optimization of Building Energy Performance and Occupant Comfort

Buildings consume tremendous energy for the improvement of living and working conditions. Control of daylight-artificial light has the potential to improve energy performance and occupant comfort in buildings. This research proposes an intelligent generalized ensemble learning technique to develop a novel control strategy for Venetian-blind positioning (up-down movement with static slat angle of 45°) of different window orientations. The proposed model helps to maintain occupant comfort and energy saving in a commercial building. The performance of the ensemble learning approach compared against Gaussian process regression, support vector regression and artificial neural network using conventional statistical indicators. Finally, the proposed data-driven model implemented in a real-time Labview-myRIO platform for the experimental validation. The data-driven model is compared with the baseline model and with the uncontrolled blind condition in terms of daylight glare, and energy consumption of lighting and air-conditioning system in the building. The data-driven model is derived using two years of data collected from a fuzzy-based daylight-artificial light integrated scheme. The blind position providing reduced energy consumption and daylight glare along with setpoint illuminance and temperature are validated. A high dynamic range image with EVALGLARE software used to verify the visual comfort based on daylight glare probability. While evaluating the overall energy savings, the ensemble learning model consumes 17% less power than the uncontrolled system and 15% less power than the baseline system. Here, though we are not controlling the air-conditioning system, the experimental validation confirmed that the air-conditioning system significantly reduces its energy consumption.

Conditions for ensuring energy-saving use of translucent structures of exterior wall envelope

The article focuses on determining the translucent structures of exterior wall envelope (TSEWE) properties influence on the total energy balance of the room. The dependence of the energy consumption for artificial lighting on the daylight factor, coefficient of relative penetration of solar radiation (CRPSR) and TSEWE area is determined for Ternopil city. The relationship between the electricity expenses for heating and cooling the room by channel air conditioners on the size and properties of TSEWE is established. Inequalities were obtained that allow us to establish the conditions under which the TSEWE use will have a positive effect on the total energy balance of the office room for the Ternopil city. According to the obtained results, it is possible to determine the thermal resistance, CRPSR and the TSEWE area at which energy savings will occur while observing the climate conditions in the room prescribed by regulations documents.