Daylight Factor Values Research Articles

The Implementation of Shaft Parts of Lighting Wells as Light Reflecting Elements in Multi-Storeys Industrial Buildings

The article discusses the problems of daylighting environment in multi storey industrial buildings. According the former scientific studies, these problems are being considered in relation to the socalled “lighting wells”. These design elements improve the quality of the indoor environment, mainly by establishing better contact between workers and the environment. The structural upgrading of original type of lighting wells is suggested. The tops of the lighting wells, which are the light supplying elements in the skylights form, are transformed to a “mining skylights”. The lower portions of the lighting wells, adjacent to floors, should be furnished with light-reflective elements. Due to this structural enclosing elements, which is additionally reflecting daylight flows to interiors, the daylight factor values increased. But such a design solution requires an additional study to prove a theoretic offering presented.

The Analysis of Natural Lighting-based Visual Comfort for Classrooms Building by Using Velux Daylight Visualizer

This study aims to determine the level of natural lighting at a school building carried out with the use of the Velux Daylight Visualizer (VDV) software. VDV is a software for analysing natural lighting on building model. The output is Daylight Factor (DF) or Daylight Natural Lighting Factor and Illumination (E). E value is the main indicator of the level lighting and visual comfort in the room by referring to simulation results referring Indonesian’s Standard of SNI 03-2396-2001 for visual comfort. Results shown the existing conditions in the classroom have a low level of lighting with majority measurement points having average lighting level below 250 lux. To improve the natural lighting quality in the classrooms, variations of walls-to-windows ratio (WWR) applied the model. The variation of WWR is conduct an experiment to substitute its value in regression equation. With the increasing size of the opening at WWR 30%, the distribution of DF values at measurement distance 1 meter and 2 meters increases compared to WWR 20%. Trend also continues to occur at WWR 40% to WWR 60%, the DF value has increased quite significantly, especially at several points blocked by walls or meeting points between light from 2 adjacent windows.

The impact of aspect ratio of buildings implementing Horizontal light pipe and shading systems on daylight performance

ABSTRACT Deep-plan buildings limit daylight use in spaces far from the building perimeter, leading to uneven daylight distribution. Integrating a Horizontal Light Pipe (HLP) as an optical daylighting system, reflective light shelves, and blinds as shading systems can reduce excessive daylight levels at the perimeter area of a building and improve daylight uniformity. Earlier investigations of HLP daylight performance concentrated on fixed building geometries, but few studies focused on the building aspect ratio, one of the design variables of building geometry that greatly influences daylight performance. This study aims to investigate the impact of the aspect ratio of buildings implementing HLP and shading systems on daylight performance. The research method was experimental, using IES-VE simulation as a tool. The daylight factor (DF), uniformity daylight factor (UDF), and useful daylight illuminance (UDI) of various aspect ratios and depths of office buildings implementing HLP and shading systems were analyzed. The results show that increasing the building aspect ratio from 1:1 to 2.1:1 sequentially increased the average DF and UDF values by 18.47% and 17.2%, respectively. Improving the building aspect ratio from 1:1 to 2.1:1 along the east-west axis improved the UDI by 3%, whereas the north-south axis decreased it by 10.2%.

Investigation of the Efficacy of Horizontal Hollow Light Tubes for Energy Conservation in Illuminating Buildings

This study investigates the properties of light transmission and distribution, examining how incident light angles impact illuminance distribution and daylight factor. Light tubes are acknowledged as promising tools to enhance lighting conditions and reduce energy consumption in building design. The study involved installing horizontal hollow light tubes, each measuring 0.5 m in length and 0.30 m in diameter, on a wooden test model. A 20-watt LED lamp was employed as the light source, and an illuminance meter recorded the values at various horizontal and elevation angles. The study’s assessment included calculating the average illuminance and daylight factor to obtain light transmission efficiency and energy-saving potential. The findings revealed that both aluminum alloy and zinc alloy tubes experienced a decrease in illuminance as incident elevation angles increased, with the most effective light transmission occurring at a horizontal angle of 90°. Notably, the aluminum alloy tube outperformed the zinc alloy tube, demonstrating more than a 15% increase in light transmission efficiency. Furthermore, the daylight factor values from both types of tubes aligned with established standards for residential and office activities, underscoring their potential as energy-efficient lighting solutions for spaces lacking natural light or with limited illumination.

STUDY OF HORIZONTAL LIGHT PIPE WITH DYNAMIC REFLECTOR IN THE TROPICS

Horizontal light pipe (HLP) is a sustainable strategy for improving daylighting quality in buildings. The reflector is one of the HLP elements that collect and direct the incoming light in the pipe. Several reflector studies of HLP systems have been carried out in the last three decades under specific sunlight conditions at certain altitudes and azimuths or static conditions. This study proposes a dynamic reflector model in response to the movement of the sun angle. This study aimed to examine the impact of the dynamic reflector tilt angle on improving the quality of light by adapting the sun angle. The method used is an experimental simulation using IESVE software. This research is located in Surabaya, with a tropics climate. The results showed that modifying the reflector to be dynamic could increase the illuminance levels up to 29.9%, daylight factor values ​​up to 29.2%, and uniformity ratio values ​​up to 33.3%.

Dynamic analysis of daylight factor, thermal comfort and energy performance under clear sky conditions for building: An experimental validation

This work focuses on daylighting performance analysis and its energy savings potential for residential building by using dynamic simulation and its experimental validation. The thermal performance of nano building material and its comparison with conventional building material has also been analyzed. The daylight factor was found in between 1 and 11% and 1–21% for the floor and wall, which is within the thermal comfort limit. The theoretical model results are compared with experimental values. The best building orientation was found to be 180° from the north or towards the south. Wind speed was found to be more than 30 kmph, which is used effectively in the natural ventilation of the building envelop. It leads to optimization of the room temperature. The heat transfer parameters, including the quantity of heat lost and gained through fabrics, thermal properties of nanomaterial have been compared with conventional building materials. The U value (heat loss coefficient) of building material defines building performance at a particular orientation. The U- values decreased to 8 times in-wall and 8.67 times in the roof of the building envelope compared to conventional building material. The model was experimentally validated, and there is close agreement between simulated and experimental daylight factor values with root mean percentage error of 1.24%. The total uncertainty in experimental measurement was found out to be 0.1421%, which is within the expectable range. Present study can be implemented in any building design with minimum modifications in any part of the world.

Shading and daylighting strategies in classrooms: a comparative study in the four climate zones in Greece using Daylight Factor values

The present work focuses to the efficient use of daylight in school buildings, which has been proved that is able to create a pleasant atmosphere, increase student productivity and comfort and also contribute to energy savings if combined with a daylight-responsive control system. The architectural-bioclimatic design contributes to the creation of technical solutions that provide daylight in existing classrooms, taking into account the climatic conditions and the needs of users. The purpose is to investigate the most prevalent shading and light redirection systems in a typical Greek classroom, in every climatic zone of Greece and come up with the most efficient ones. Research takes into consideration the distribution of daylight on working level and the total heating energy consumption throughout the school year, ensuring conditions of visual comfort. After evaluating and comparing the data, the outcome of this research demonstrates the most efficient shading system for each climatic zone, in order to achieve visual comfort and energy savings.

The effectiveness of dayligting through the toplighting design in large-volume building models

The utilization of daylighting as an effort to reduce the usage of building energy needs to be optimized. This is because, low-rise buildings with large volumes require specific strategies for proper light distribution throughout the space. Hence, this study aims to explore and compare the effectiveness of daylighting in the openings design of skylight, roof monitor, and sawtooth in large-volume buildings in Bandung. The effectiveness is assessed by examining lighting performance based on distribution patterns, the value of Daylight Factor (DF), and the Coefficient of Uniformity (CU). Experimental research method with simulation program known as Velux Daylight Visualizer 3.0 is used to present and analyze the lighting data. The results showed that the type, position (openings' height and distance), as well as the opening direction affected the distribution patterns and daylighting performance. Based on the simulation, the skylight opening is the most effective in meeting the standard value of Daylight Factor (> 2%) and Coefficient of Uniformity (CU min. 0.3 and DF min. 0.8%). Thus, space and openings model with a percentage roof area of 16.3% in the simulation can be used as a reference for large-volume buildings because, it meets the requirements of Daylight Factor value and sufficient Coefficient of Uniformity.

Influence of the Adaptation of Balconies to Loggias on the Lighting Climate inside an Apartment Building under Cloudy Sky

The reconstruction of balconies and loggias is a key element of the renovation of apartment buildings. Artificial light will never replace natural light. Every day, one must make full use of the potential of daylight and enjoy an advantage—free-of-charge natural light entering the interior. When renovating balconies, people often change the character of this protruding structure from a façade to a loggia. This is also the subject of this paper. For the evaluation of the daylighting conditions prevailing in residential building, the Daylight Factor (DF) was considered as the parameter for indicating the quantity of admitted daylight. The DF values and illuminance—CIE overcast sky were calculated using DIALux 9.1 software. The aim of the paper is to compare two variants of the level of daylight in the rooms of the residential building. One option to bring in even more natural light than a window is a variant with balconies. Loggias are satisfactory in terms of static and thermal technology, but daylight conditions are deteriorating. The article provides an insight into the solution of the renovation of balconies and loggias in a specific apartment building. The result shows their influence on changes in the conditions of natural daylight in the interior of two selected rooms.

Effective Use of Daylight in Office Rooms

The rational use of daylight can significantly reduce the cost of electricity for artificial lighting. This research aims at investigating the parameters of translucent structures of building envelope, and the value of daylight factor, for which maximum efficiency of daylight usage is achieved in office rooms. The study analyzes the dependence duration of daylight autonomy in office rooms, on the value of daylight factor for four European cities. The specific daylight autonomy (h/(year∙m2)) of office rooms were found. It was proved, that regardless the size of the rooms, the maximum specific daylight autonomy in Ternopil city (at illumination of 300 lx, which is prescribed by regulations), with lateral daylight, occurs when the daylight factor is in the range of 1.7% to 1.9%. Maxima – at 1.8%. At illumination of 500 lx, the maximum specific daylight autonomy will occur at a daylight factor range of 2.6% to 3.0%. Maxima – at 2.8%.

Influence of Roof Windows Area Changes on the Classroom Indoor Climate in the Attic Space: A Case Study

Windows are a complex part of building design and provide a considerable benefit, including to school buildings. For the evaluation of the daylighting conditions prevailing in classrooms, the daylight factor (DF) was considered as the most appropriate parameter for indicating the quantity of admitted daylight. The DF values and CIE overcast sky were calculated using Velux Daylight Visualizer 3 software. The task of the paper is to compare various roof window openings in relation to the level of daylight in the attic, looking to optimize the use of the attic for teaching. The indoor air temperature has a general influence on comfort in the interior, in addition to daylight. In winter, the situation is not critical. The thermal insulation properties of packaging structures are sufficient. The situation is worse in summer, due to the fact that the heat-storage properties are undersized and there is excessive overheating of the indoor air. Four variants of roof windows and their influence on the overall microclimate in the attic are compared. The variant without roof windows is a suitable solution with regard to minimum overheating, but the worst situation for daylight. In order to receive even more light from the window (by moving windows to the top of the roof), we can use variant 2. Based on a combination of daylight calculations and summer temperature, a graphical dependence on window size prediction in terms of top and combined lighting is derived. This was hypothesized without shading the windows. Of course, the shading elements of these windows or cooling are expected in the summer. Finally, the energy required for cooling is compared depending on the size of the windows and achievement of the permissible temperature.

PENGARUH ELEMEN DESAIN BANGUNAN TERHADAP PERFORMA PENCAHAYAAN ALAMI PADA LAPANGAN BULUTANGKIS INDOOR BUMI PANCASONA KBP BANDUNG

Abstrak- Desain lubang cahaya yang baik pada bangunan bisa dilakukan untuk memaksimalkan potensi pencahayaan alami pada negara tropis. Bangunan olahraga bulutangkis merupakan salah satu fungsi bangunan bentang lebar yang sensitif terhadap pencahayaan alami dan membutuhkan teknik khusus dalam memasukan cahaya alami ke dalamnya karena bentangnya yang lebar. Terdapat tiga aspek kenyamanan visual yang harus dipenuhi oleh desain pencahayaan pada bangunan olahraga bulu tangkis yaitu daylight factor 2%, persebaran illuminasi dan efek silau. Ketiga aspek kenyamanan visual tersebut akan menjadi titik berangkat penelitian ini sebagai variabel penelitian.Penelitian ini bertujuan untuk mengetahui pengaruh elemen desain terhadap performa pencahayaan alami pada objek studi Bumi Pancasona sport center dengan cara eksplorasi elemen desain. Penelitian dilakukan dengan cara mengevaluasi performa objek studi, dan menganalisa pengaruh elemen tapak dan bangunan terhadap performa pencahayaan alami pada bangunan. Dari evaluasi performa pencahayaan alami pada objek studi, akan diketahui elemen desain yang paling berpengaruh terhadap pencahayaan alami pada lapangan bulutangkis. Elemen desain yang berpotensi meningkatkan performa pencahayaan alami pada objek studi akan di eksplorasi. Eksplorasi dilakukan dengan simulasi program komputer Velux untuk menciptakan keadaan terkontrol.Berdasarkan hasil evaluasi, objek studi belum mencapai standar kenyamanan visual yang berlaku dengan nilai daylight factor 0.1%, persebaran illuminasi yang kurang merata, dan tidak terjadi silau. Elemen desain yang berpotensi meningkatkan kenyamanan visual pada bangunan adalah posisi jaring pada interior bangunan, luas bukaan dan posisi bukaan pada bangunan, tiga elemen tersebut akan dieksplorasi lebih lanjut sebagai upaya meningkatkan kenyamanan visual. Hasil eksplorasi yang memberikan nilai paling mendekati standar adalah eksplorasi desain jenis saw tooth, dengan nilai daylight factor 1.1%, persebaran illuminasi paling merata di antara semua eksplorasi dan tidak terjadi silau pada lapangan sepanjang tahun. Berdasarkan hasil eksplorasi, setiap elemen desain yang di eksplorasi akan meningkatkan performa pencahayaan alami yang berbeda tergantung kebutuhan pada bangunan dan aktivitas ruang.sarana yang ada.

Analysis of Point Daylight Factor (PDF) Average Daylight Factor (ADF) and Vertical Daylight Factor (VDF) under various unobstructed CIE Standard Skies

The usual method for computing natural illuminance for a given location in a building is the daylight factor (DF) approach, which is based on the traditional overcast sky without sunlight, as defined by the International Commission on Illumination (CIE). In 2003, the CIE adopted a range of 15 skies as international standard models that represent the actual skies of many places and cover the whole probable spectrum of skies found in nature. Previously, we developed a number of calculation tools to predict daylight illuminance for rooms facing different orientations under various CIE Standard skies. This paper presents the work on the calculation of the point DF (PDF), average DF (ADF) and vertical DF (VDF) under various overcast and non-overcast skies. The strong correlations between these three DF types can help to estimate the required DF values for architectural and daylighting designs and evaluations.

The influence of sun-protective devices on natural Light distribution in premises

The article observes the new approach to a lighting environment in premises of civil buildings in hot and sunny climatic conditions. Under such conditions, the use of sun-protective devices (SPD) of different types and geometrics becomes traditional way of passive climate control in interiors. However, the authors determined, that the most traditional types of external SPD (such as canopies or awnings) have a different effect on indoor lighting environment due to the conditions of external natural illumination under overcast sky vault or clear sky conditions. In the first case, the stationary SPD act as shadowing elements, which block the light flows from the CIE standard overcast sky. In the second case, which corresponds to a clear sky sunny conditions, such SPD block the solar radiation, decreasing overheating and reflect sun beams to an interior, increasing the value of daylight factor (DF) at least in the furthest from windows areas of a premise. The proposed solutions allow reducing electric power consumption in buildings.

Improvement of the internal light environment on the objects of transport infrastructure with aid of sun-protective devices

The article analyzes the problems of outdoor stationary sun-protective devices (S.P.D.) and their influence on the natural daylighting levels in the premises of civil objects of transport infrastructure under the hot and sunny climatic conditions of the environment. It is noted, that with clear sky, typical for the said climate, non-uniform luminance of the sky differs seriously from the luminance of standard overcast sky with diffused light, recommended by C.I.E. (Commission International D’Eclairage).A conclusion is made, that with clear sky conditions, a sun-protective devices in the form of stationary canopies (awninas) help to improve the lighting environment in the premises considered. This becomes possible due to reflected sun flow from the surfaces of SPD employed, as well as due to rise of a daylight factor values in farmost from windows zones of interiors, because of the increase of luminance factor values of the sky areas, observed from these zones. Thus, the SPD considered, in the hot and sunny climatic conditions are able not only to carry out their main function of passive method of solar radiation and thermal control in the interiors, but also to act as an efficient measure to improve lightning environment of the premises in question.

The effect of opening on building envelope toward daylight performance in Betang House at Central Borneo

The traditional house is able to adapt the climate around them and it can reduce the burden of energy use to adjust the comfort of occupants. The development pattern of occupants’ activity adjusts to a modern life that indirectly affects the function and condition of the building. This gives rise to a new phenomenon, whether development sheath openings in buildings can still meet the needs of lighting for the activity of the occupants. This research was conducted with the aim to clarify and identify the deployment sheath openings in buildings on the performance of natural lighting in Betang House. The method experiment with the help simulation is used to find a causal relationship from deployment sheath openings in Betang House building performance against natural lighting. The experiment is conducted with the simulation using Autodesk Ecotect Analysis 2011. The final result of the research indicates deployment openings in the facade have natural lighting performance that already meet the standards of the lighting for the activity. Deployment openings with the addition of extents openings could increase illuminantion and daylight factor space by 10% and 14%, but the value of the resulting illuminantion uniformity is not too high. The addition of height can increase the value of daylight factor of 13%. The ratio of lighting uniformity additional height opening is higher, but that resulted being lower illuminantion 0.3%. Rumbak tahansengan deployment at facade can improve the ratio of the lighting uniformity for activity up to 9.6%.

Integrated Lighting Efficiency Analysis in Large Industrial Buildings to Enhance Indoor Environmental Quality

We present observations from evaluation of internal environmental quality of industrial halls with priority on daylighting in combination with the integral lighting. The physical parameters related to indoor lighting in large industrial halls in winter and summer periods were analyzed using in situ measurements and computational methods. These are part of a comprehensive research on indoor environmental quality of industrial halls with the aims of saving energy and providing a comfortable environment for the workers while improving the productivity. The results showed that the procedures used for evaluation of residential or office buildings may not be used for industrial buildings. We also observed that the criteria of occupants’ comforts for indoor industrial buildings may differ from those of other kinds of buildings. Based on these results, an adequate attention is required for designing the industrial buildings. For this reason, appropriate evaluation methods and criteria should be created. We found the measured values of daylight factor very close to the skylight component of the total illumination. The skylight component was observed on average 30% that of the measured daylight factor values. Although the daylight is not emphasized when designing the industrial buildings and its contribution is small, but it is very important for the workers psychology and physiology. The workers must feel a connection with the exterior environment; otherwise, their productivity decreases.

Light distribution in air-supported pneumatic structures: Comparison of experimental and computer calculated daylight factors

This study examines daylight distribution and illumination levels with daylight factors (DFs) inside an air-supported (pneumatic) structure (50.0 m long, 25.0 m wide and 11.0 m high). The DFs values were determined experimentally for 45 different points on the playground floor. Two sets (set1 and set2) of time dependent illuminance measurements were performed at overcast but variable (5400-2400 lx) sky conditions similar to the CIE overcast sky. Results revealed that the DFs values were in the range from 1.1% to 1.7% and were not evenly distributed across the interior, with the greatest values at the centre and the smallest at the edges of the playground floor. Composition of the membrane was studied with SEM micrographs and by measuring the Raman and Infrared spectra. Hemispherical (total) transmittance (TT(λ)) and reflectance (TR(λ)) spectra (300–2500 nm) of the membrane used were measured and averaged over the visible spectral region giving TTvis and TRvis and haze, the latter confirming that fabrics strongly scattered the incoming solar radiation. The surface of the fabrics was characterized by contact angle measurements which indicates that the fabrics were weakly hydrophobic and strongly soiled. Daylight factor values obtained from the DAYSIM computer simulations matched well the experimental ones allowing further studies of daylighting inside the translucent dome. It was found that various colour patterns substantially affected the DFs values. DAYSIM calculations also demonstrated the possible use of aerogel insulation blanket as composite fabrics for air-supported structures.

Assessment of the Entropy of Spatial and Time Distributions of Rooms Daylighting: a Possible Tool for a Sustainable Design

The indoor visual comfort of subjects faced with indoor ambient lighting varies with the position of the subject and is not constant over time. Average performance indexes, such as the mean value of Daylight Factor and Daylight Autonomy, are commonly used to analyse lighting distribution. These indexes, however, don’t properly take into account either the spatial or the time distribution of values affecting the non-uniformity of environmental lighting. Indeed, these are limited to the definition of a mean value or to the assessment of time availability of daylighting. This paper examines spatial and temporal non-uniformities in indoor lighting as possible causes of discomfort for occupants. The goal is to propose and verify possible supplementary tools to integrate traditional methods of evaluating ambient indoor lighting. Use of the entropy theory with a probabilistic approach can help to obtain more detailed information about the environment. The authors have developed a case study of several sample environments and have analysed the relationships between lighting parameters and typical indices of information theory. Results show that this approach could be a useful way for predicting possible indoor visual comfort issues and for developing a preliminary assessment to a sustainable building design.

Courtyard housing in midrise buildings: An environmental assessment in hot-arid climate

This study is an evaluation of the environmental impacts of courtyard integration in midrise housing in the hot-arid climate of Dubai, The United Arab Emirates. Computer simulation is utilized to determine the overall energy consumption, energy savings potential and available daylight levels. The study is carried out in three steps. First, a comparison between conventional and courtyard buildings is conducted. Second, the effects of number of floors, type of glazing, wall thickness and insulation type & thickness on the performance of a courtyard type building are simulated. Lastly, an optimized courtyard model encompassing the best of each of the parameters studied in the second step is generated and tested. Converting a six-floor building from the conventional form to a courtyard form, keeping all building materials and parameters the same, resulted in a 6.9% reduction in the year-round total energy consumption. The optimized courtyard model, including variations on building materials, resulted in 11.16% reduction in the overall year-round energy consumption when compared to the reference conventional form building. Comparison between the daylight performance of the two forms showed that the courtyard form was better than the conventional form during both winter and summer test days with daylight factor values close to those recommended by the USGBC, which means that the courtyard form provides more usable daylight without excessive glare.