Energy Demand For Lighting Research Articles

Multi-objective modified satin Bowerbird optimization algorithm used for simulation-based energy consumption optimization of yearly energy demand of lighting and cooling in a test case room

An effective method of optimizing building energy performance through simulation is introduced in this study. The Modified Satin Bowerbird Optimization Algorithm and the DesignBuilder simulation tools are used to find optimal solutions for improving building energy efficiency. Five distinct climatic zones of China are examined in terms of decision variables including window size, overhang characteristics, and building orientation. The objective functions are based on the energy demand for lighting and cooling over a year. Analyses of optimization employing either a single-criterion or a multi-criteria approach delve into the interactions between these functions. According to the results, buildings had a reduction of 24.0 %–42.7 % in their overall yearly energy consumption. 22.9 %, 24.0 %, 35.1 %, 37.2 %, and 42.7 % yearly overall energy consumption reduction are specific to Harbin, Beijing, Guangzhou, Shanghai, and Kunming, respectively. Under varying weather conditions, architectural decision variables have a significant impact on energy consumption.

Impact of Passive Design Strategies on Environment, Cooling and Lighting Energy Demand. A Weighted Least Squares-Based Approach

Abstract The energy transition requires optimal knowledge of the thermal behaviour of different passive strategies. This paper explores the impact of 28 variables representing 4 shading devices, 5 external wall compositions (U w), 3 window types (U w), 4 window-to-wall ratios (WWR), 4 types of climates represented by 4 cities, and 8 orientations. Applying the Latin hypercube sampling method, a campaign of 300 dynamic thermal simulations is performed to assess the impact of the variables selected using the weighted generalised linear regression method for the energy demand for air conditioning, the energy demand for lighting, and the environmental impact expressed in kg of CO2. The model of energy demand for cooling (R² = 0.951) shows that the weather data is the variable that most explains energy demand, followed by the glazing ratio, the thermal characteristics of external walls, and shading devices. The model explaining the energy demand for lighting (R² = 0.945) shows that the WWR and shading devices, the weather data, and the orientation, influence the energy demand for lighting. Finally, the model explaining the embodied carbon footprint (kg of CO2) (R² = 0.989) shows that external walls and window type are the main influencing factors. Finally, the best combination for balancing the cooling-lighting-embodied carbon balance equation is discussed.

Occupant behaviour and the potential of automating lighting control in terms of energy consumption – is there a link for residential buildings?

The implementation of occupancy-controlled and daylighting-dimmed lighting systems has an impact on the energy consumption of residential buildings. The BAC factor method of EN ISO 52120-1 estimates that 8% of the lighting energy can be saved compared to conventional manual control. However, it is assumed that their ability to potentially lower the lighting energy consumption is strongly related to external factors, such as the extent of daylight entrance and the behaviour of the inhabitants. By means of simulations in EnergyPlus, the performances of automated and manual lighting control are compared for an apartment and semi-detached building located in Brussels (Belgium) with variation in the occupant behaviour and orientation.It appears that an automated lighting control including 0-100% dimmer reduces the lighting energy demand for all investigated cases with savings up to 38.4%, whereas a similar control without dimmer does not necessarily reduce the lighting electricity demand. However, the results show a considerable variation, making prediction methods as the BAC factor method highly inaccurate. The actual relative energy performance depends on the automation system, type of building, orientation and occupant behaviour (i.e. number of inhabitants and occupancy rate). Hereby, the number of inhabitants has the most considerable impact on the relative energy performances with differences up to 50%, while the occupancy rate shows a significant correlation, especially for low numbers of inhabitants.

Assessment of the impacts of window-to-wall ratio and overhangs on building energy performance – Kabul, Afghanistan

Windows have the potential to save energy in a significant way. Therefore, the analysis and optimization of the Window-to-Wall Ratio (WWR) play an important role in improving energy efficiency in buildings. Windows are always beneficial to utilize daylight and reduce lighting energy demand. However, solar heat gain is advantageous during cold days and disadvantageous on hot days. As the configuration of the window areas varies according to the geographical location, the objective of this study is to evaluate the impact of WWR on the energy performance of buildings in the cold semi-arid climate of Kabul, Afghanistan. In this study, various energy simulations were conducted for three types of building shapes (Square, Rectangle, and “L”-Shape) to determine the most energy-efficient proportion of windows and overhang sizes in different cardinal directions. Based on the simulation results, windows on south façades have notable energy-saving potential in Kabul's climatic conditions. However, increasing the window size on north, east, and west façade leads to an increase in the total heating and cooling energy consumption. The optimal WWR of the south façade window for square, rectangular, and “L”-Shaped is 0.7, 0.55, and 0.55, respectively. Additionally, the findings indicate that overhangs in all orientations slightly affect the total energy demand as they only reduce cooling load. The study concludes that optimizing the windows on the south façade reduces energy demand by up to 8.13% if no windows are provided in other directions, while the total energy consumption rises by up to 36% as the WWR on the north, east, and west façades increase from 0 to 0.8.

Advances in the design of an alternative power generation device using piezoelectric

This article will give the progress of the project of design of a device of alternative energy generation using piezoelectric, applied in the improvement of the lighting of an urban dwelling. Giving the background of the piezoelectric effect, a diagnosis of the conditions of the housing unit in terms of the energy demand for lighting, its vehicular capacity and road conditions, as well as the proposed solution to the demand for electrical energy, indicating the necessary electronic components in the first proposal and ending with the initial design and technical analysis, to conclude with the results of the research project. It is also important to consider that within the 13 modules that are required to form the speed reducer when a vehicle passes it will not pass through the 13 modules, but only a few, so the energy generated will also have variations in the results; unless a way is sought that when the vehicle passes over the reducer, all modules are pressed at the same time.

Towards the construction of a sustainable rural energy system: Case study of an indigenous community in Mexico

One of the challenges that rural communities face is the satisfaction of their energy demand through sustainable processes, where the production, distribution and final consumption of energy are involved in an efficient, affordable, and non-polluting way. This proposal analyzes, for a rural community in Mexico, the economic and environmental impacts associated with meeting the energy demand for lighting, cooking, entertainment and technology needs, hygiene, education and mobility; by formulating three different scenarios: (a) estimation of current energy consumption (baseline) (b) satisfaction of said needs through locally available renewable energy resources, and (c) satisfaction of needs and their potential impacts by making use of efficient technologies with respect to current technologies, for refrigeration, firewood combustion, and lighting. The results show a current distribution in energy consumption of 66.8 % for cooking, 26.2 % for hygiene, 6.6 % for mobility, 0.8 % for lighting, 0.6 % for entertainment and technology, and 0.03 % for education. In total economic expenditure, the percentages by type of need are 58 % for mobility, 28 % for cooking, 11 % for hygiene, 2 % for lighting, 1 % for entertainment and technology, and 0.1 % for education. The environmental impact in terms of nitrogen oxide (NOx), methane (CH4), and carbon dioxide (CO2) emissions is, like the energy consumption, oriented to a greater extent towards energy needs that require thermal energy. Our evaluation of these scenarios has shown that the available energy resources are sufficient to supply all the local energy demand, through technologies such as solar panels, LED lights and efficient combustion stoves; and only less than 5 % of the total production of wood residues that the community generates is required to achieve this satisfaction. Finally, some guidelines are suggested for an energy management strategy that is based on the scenarios proposed for the studied community. This article provides information for the construction of sustainable rural energy systems and for the development of energy management schemes in rural and self-governing communities.

Photovoltaic Roundabouts for Enhancement of Self-Sufficiency and Resiliency

Roundabouts have become a common type of intersection design in many countries. The area of the center island can be used to install a photovoltaic system to power local loads such as lighting systems. The objective of this study is to evaluate the degree of self-sufficiency that a roundabout can achieve depending on the availability of the area for the installation of a photovoltaic system and the energy demand for lighting. The methodology is divided into five steps aimed at calculating the parameters required to characterize the roundabouts from the point of view of the electricity that can be generated by the photovoltaic systems installed, and then to evaluate the energy consumption required to operate the different system solutions for lighting. The mini roundabouts are not considered as a location for the photovoltaic system; in fact, the minimum diameter must be between 29 and 34 m. Considering the available irradiance in Italy, systems with monocrystalline silicon modules are sufficient to ensure energy self-sufficiency at diameters of 24 m or more. Systems with polycrystalline silicon modules are suitable to ensure energy self-sufficiency at diameters of 25/26 m or more. Photovoltaic (PV) technology continues to make progress in increasing efficiency, such as bifacial PV modules. This means that even smaller roundabouts could be eligible for a PV system sized to meet local electricity needs.

Theoretical Impact of Building Façade Thickness on Daylight Metrics and Lighting Energy Demand in Buildings: A Case Study of the Tropics

In daylighting design, variation of building façade thickness (f) will result in variation of the daylight opening areas, which in turn will modify the values of daylight metrics within the space. However, studies dedicated to investigating the impact of varying f on indoor daylight metrics are relatively scarce. This study, therefore, aims to assess the theoretical impact of various façade thicknesses on various daylight metrics and lighting energy demands in a reference office space. Analytical calculations are performed using an outdoor diffuse illuminance profile of a tropical city. The building façade thickness values are varied within 0–0.50 m, at window-to-wall ratios (WWR) of 25%, 50%, and 75%. Based on sensitivity analysis, it is found that variation of f yields different impacts on the observed metrics, with sDA300/50% being the least influenced. Among all metrics in the central calculation point, DA300, UDI-a, and UDI-a′ yield relatively small coefficients of variation, and thus, have the lowest uncertainty with respect to f. Among all metrics for the entire room, sDA300/50% and sUDI-a50% have the lowest uncertainty, with interquartile ranges of no more than 0.4%. Overall, the contribution of this study is providing insight into the impact of façade thickness on various daylight metrics in indoor spaces, particularly in the worst-case scenario under the standard CIE overcast sky.

Passive system optimization in office buildings using a reference testbed building

AbstractThe purpose of this research is the application of a passive design strategy for office buildings, the wall-window-ratio optimization under moderate climate. A simplified thermal and lighting simulation model of an office research building served as reference testbed for thermal comfort, daylight factor and illuminance as well as heating, cooling and lighting energy demand assessment. These six performance types of similarly oriented room groups are evaluated via a self-developed weighting process to determine the orientation dependent optimal wall-window-ratio of all room groups. This multi objective optimization applies in a broad range of office buildings under moderate climate.

A tool for generation of stochastic occupant-based internal loads using a functional data analysis approach to re-define ‘activity’

In building energy simulation (BES), internal loads are typically defined as hourly schedules based on occupant-related ‘activities’ assigned to each building zone. In this paper, a data-centric bottom-up functional data analysis model is used to examine how activities in a building correlate with energy demand for plug loads and lighting. Functional principal component analysis and hierarchical clustering of the principal component scores have been used to explore the links between the data and zone activity. The results show that plug loads show limited links to activity to the extent that the activity determines the variability of the data. The lighting loads show little correlation with zone activity but instead are determined primarily by the building control system. A novel methodology is proposed for the generation of stochastic load data for input into BES. This methodology has been developed into a tool for stochastic load generation which is available online.

Thermal-energy and lighting performance of aerogel glazings with hollow silica: Field experimental study and dynamic simulations

The excellent thermal insulation properties of aerogel glazing systems make them an interesting building solution, especially in cold climates. When aerogel glazing systems provide less solar heat gain factor, they could be useful in warm and hot regions (such as Tokyo, Rome and so on) because buildings in such areas are often designed to minimize cooling energy demands. If a sort of opaque powder is mixed with aerogel granules, able to stick to each granule and to cover the aerogel surface discontinuously, the mixture can thus reduce solar transmittance, contributing to daylight usage with less glare risks and cooling energy demand reduction, without shade or blinds, keeping as high thermal performance as aerogel. This innovation is examined in the present paper, by presenting the following solution: a double glazing unit with a mixture of silica granular aerogel and hollow silica powder in the gap (AGS), in order to reduce the solar factor. The solution is tested through in-field experimental campaigns and numerical analyses, making available a set of data not found in literature, where mixtures of aerogel and powder were never studied. The air temperatures in the test Room with AGS, especially the peak values, are lower than the ones in the reference one with installed a standard glazing system (SGS). The same behaviour is observed in several experimental campaigns in different seasons: in mid-season 1 the highest differences are of about 6–7 °C, whereas in summer they reach 12–16 °C. Significant differences in terms of illuminance are also observed: the calculated Useful Daylight Illuminance (UDI) shows AGS values 57% higher than SGS, highlighting the aerogel ability to diffuse light and to reduce glare. Experimental data were used for energy analyses of a reference building in Tokyo. AGS outperforms a low-e glazing in terms of heating energy demand: the reduction varies in the 22% (North) − 62% (South) range. The lighting energy demand is quite similar: electricity demand increases in the 3–6% range. Finally, the internal shade on the reference glazing has a significant impact on the estimated energy demand, both for cooling and heating.

Financial feasibility of solar PV lanterns for households of a remote village cluster without access to electricity

In this study, the financial feasibility assessment of adopting state-of-the-art designs of solar PV lanterns by the households of a remote village cluster in the state of Rajasthan, India has been undertaken. LED-based solar PV lanterns are expected to save kerosene and meet their lighting energy demand. Based on a survey of the village cluster, the household level requirement of solar PV lanterns (three numbers each with a 3-W LED lamp), annual kerosene saving (approximately 100 litres) and the values of several measures of financial performance include discounted payback period (merely 4.7 years), net present value (Rs. 11263/-) and benefit to cost ratio (2.37) has been estimated. From a financial perspective an investment in the solar PV lanterns by a household appears to be quite attractive and may be explored by energy service companies. The results of detailed calculation undertaken have been presented in the paper and discussed.

Energy savings in greenhouses by transition from high-pressure sodium to LED lighting

Greenhouses in high latitudes consume vast amounts of energy for heating and supplemental lighting. Light emitting diodes (LEDs) have been suggested as having great potential for reducing greenhouse energy use, as they are extremely efficient at converting electricity to light. However, LEDs emit very little heat, which must be compensated by the greenhouse heating system. Thus, it is unclear how much energy can be saved by LEDs when the need for extra heating is taken into account. This study presents a first analysis of the energy demands for greenhouses transitioning from high-pressure sodium (HPS) to LED lighting, providing a quantification of the total energy savings achieved by LEDs. Model simulations using GreenLight, an open source greenhouse model, were used to examine a wide range of climates, from subtropical China to arctic Sweden, and multiple settings for indoor temperature, lamp intensity, lighting duration, and insulation. In most cases, the total energy saving by transition to LEDs was 10–25%. This value was linearly correlated with the fraction of energy used for lighting before the transition, which was 40–80%. In all scenarios, LEDs reduced the energy demand for lighting but increased the demand for heating. Since energy for lighting and heating is often derived from different origins, the benefits of a transition to LEDs depend on the environmental and financial costs of the available energy sources. The framework provided here can be used to select lighting installations that make optimal use of available energy resources in the most efficient and sustainable manner.

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Haematococcus pluvialis is one of the most abundant sources of natural astaxanthin when compared with other microorganisms, and has attracted the interest of the market thanks to its health benefits. We investigated the environmental performance of the cultivation of H. pluvialis and the astaxanthin production processes through a comprehensive Life Cycle Analysis (LCA). This study compares the potential environmental impact of three photobioreactors (PBR) available on the market: the flat panel airlift , the green wall panel , and the unilayer horizontal tubular PBR . These systems have different technical settings: the flat panel airlift has a double-sided light emitting diode (LED) illumination system and is placed inside a building; the green wall panel is located outside and equipped with one-side LED lighting; the unilayer horizontal tubular is placed outside without any artificial lighting. Two different functional units were considered: one kg of H. pluvialis (80% dw) and 1 kg of astaxanthin. Where 1 kg of astaxanthin was selected as functional unit, as the content of astaxanthin in the biomass is low, the system expansion method was applied.The LCA results, based on original data from pilot-scale production, indicate that the system design, and the energy mix used have a significant environmental impact, due to differences in algae productivities and energy demand. For indoor systems, even with light-emitting diodes (LED), the energy demand for lighting is the main contributor to climate change. This contribution decreases significantly if the share of renewable energy increases. In the case of the green wall panel another main climate change contributor is the material used for the diode production, including tin and molybdenum. Although the astaxanthin yield is higher in the flat panel airlift and green wall panel, electricity production systems still constitute an environmental burden. For this reason, the system with the lowest environmental impact is the unilayer horizontal tubular, i.e. the photobioreactor where no artificial light is used.

Optimization of the design of the primary school classrooms in terms of energy and daylight performance considering occupants’ thermal and visual comfort

One of the top priorities in the building design process is minimizing energy consumption. Moreover, the level of occupants’ comfort directly affects their learning ability Therefore, this paper uses a multi-objective approach to optimize the architectural design features, including some newly examined ones, that define the geometry of a classroom. Furthermore, to create a practical methodology for minimizing lighting energy demand, we put the technique of dividing the class into independent, controllable lighting zones into practice for the first time. This research aims to introduce an optimized primary school classroom that meets both inhabitants’ comfort needs and energy efficiency. For this, we first developed a parametric model using the Grasshopper plug-in for Rhino. Afterward, the environmental plug-ins of Honeybee and Ladybug were employed to evaluate energy performance and thermal comfort and find optimized solutions. The last step was assessing the occupants’ visual comfort for each of these optimized solutions and selecting the final optimum designs. This two-phase optimization procedure has led to the reduction of total energy demand, up to 47.92 kWh/m2, and improvement of occupants’ thermal and visual comfort. The results show that the proposed methodology can provide designers with a guideline for designing a sustainable classroom that fulfills their preferences as well as encouraging them to use innovative ways for energy conservation.

Measurements and Simulation Study of Daylight Availability and Its Impact on the Heating, Cooling and Lighting Energy Demand in an Educational Building

This paper deals with the impact of the use of daylight on the overall energy demand for heating, cooling, and lighting in educational buildings. The energy performance of buildings is currently of the utmost importance as current European regulations, starting from 31st December 2020 impose that all new buildings must meet nearly zero-energy building requirements. This paper presents a study of the illuminance distribution in an educational room obtained from measurements and simulation results using two different models. One of the models, integrated with a thermal simulation software, was used to estimate the impact of daylight on the energy demand. The analysis included the use of various window types, lighting control system, reference point location, and daylight calculation model for a sample room in an educational building. Results of the analysis indicate that, due to the high share of lighting demand (reaching up to 78% of the primary energy balance), there is a need to take into account the efficiency of lighting systems during the design process to correctly determine the actual energy balance of a building, increase the quality of the design of lighting systems, as well as to select the optimal parameters of windows.

The Energy Saving Potential of Wide Windows in Hospital Patient Rooms, Optimizing the Type of Glazing and Lighting Control Strategy under Different Climatic Conditions

If not properly designed, the adoption of large windows can sometimes have a negative impact on building energy demand. For this reason, aggravated by the outdated building envelope of the healthcare building stock, large fenestration systems are usually avoided in hospitals, especially in old structures. However, with appropriate glazing specifications, the adoption of wider openings can result into significant energy savings, lower costs and strong positive effects on patients and staff well-being. The present study investigates how different window sizes and types of glazing affect heating, cooling and lighting energy demand in a hospital patient room. The objective is to evaluate the energy savings that may be obtained when installing larger windows and to identify the glazing properties allowing one to reach the maximum energy reductions. Simulations were carried out using nine diverse glazing systems, already available on the market, and their energy performance was evaluated in relation to two different window areas: a common size opening, characterized by a 25% Window-to-Wall Ratio (WWR), and a floor to ceiling window, with 77% WWR. The analysis was conducted taking into consideration four different orientations in four Italian cities, supposing two artificial lighting control strategies. The results highlighted how the adoption of wider windows with appropriate glazings and a daylight-linked dimming lighting control strategy may lower the primary energy demand up to 17%.

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.

Multi-criterion optimization of integrated photovoltaic facade with inter-building effects in diverse neighborhood densities

Inter-building effects have been proved to have significant impacts on the energy and indoor environmental performance of adjacent building developments in densified urban environment. Therefore, this study presents a multi-criterion design optimization and decision-making approach for an integrated PV facade design considering miscellaneous inter-building factors as well as corresponding criteria specification in major green building assessment schemes. The impact of the surface reflectance and façade geometry is quantified for the lighting energy demand, HVAC energy demand, photovoltaic (PV) energy supply and indoor visual discomfort time respectively with a robust global sensitivity approach in diverse urban density scenarios. Wall reflection is determined to be the most important urban design factor contributing to 34%–66% variation of different performance indicators as per the availability of solar radiation on different building surfaces. Multi-dimension parametric analyses and design optimizations of PV envelope design parameters are then conducted for different neighborhood densities with fixed surface properties of peripheral building facades. Sensitivity indices of window and shading design parameters are subject to significant variation when considering surface properties of peripheral buildings. Furthermore, the performance of two different decision-making strategies (i.e. Technique for Order of Preference by Similarity to Ideal Solution and Minimum Distance to the Utopia Point methods) is compared based on criteria weightings from green building assessment schemes. The final optimum solution closest to the ideal is then determined by two-dimensional charts of objective functions. The integrated design optimization considering peripheral reflection can change the estimated net energy demand by up to 8.84% (mainly in PV supply and lighting demand). These research findings can promote the integration of synergetic energy and indoor environment design strategies and expand the penetration of renewable applications in urban areas.

Energy efficiency improvement in hospital buildings, based on the example of a selected type of hospital facility in Poland

Energy demand in hospitals is of highly diverse nature: heat energy, cool energy and electricity. A guarantee of energy supply is required to ensure continuity of medical procedures. Taking care of the lowest possible costs of hospital operations, special attention should be paid to energy efficiency of the installations used in the hospital buildings. The paper presents an analysis of energy demand for heating, cooling, ventilation and lighting in an example hospital in Poland. The selected object was considered a reference as it was built according to a repetitive construction plan, according to which several dozen other hospitals were built in Poland. On the basis of data from 2013-2017, a summary of heat, cold and electricity demand for the hospital in its current technical condition was prepared. Concepts of technical and economic modernization of systems using energy in the analysed facility were proposed, assuming different ranges of changes for individual installations in the hospital. After the analysis of various modernization options, a project was proposed combining the use of heat pumps, photovoltaic installations and generation of heat and cooling in trigeneration, all of which allowed to reduce the costs of operation of the hospital energy systems by about 31%.