JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING https://doi.org/10.1080/13467581.2022.2160636 BUILDING STRUCTURES AND MATERIALS Improving illuminance performance by implementing a kinetic façade system: case study of office building in Dubai a b Hanan M. Taleb and Rudy Moarbes a b Faculty of Engineering, British University in Dubai, Dubai, UAE; Master’s of Sustainable Design of Built Environment, Faculty of Engineering, British University in Dubai, Dubai, UAE ABSTRACT ARTICLE HISTORY Received 11 January 2022 Buildings incorporating kinetic architecture are designed to allow parts of the structure to Accepted 16 December 2022 move without reducing the structural integrity of the building. This is believed to substantially improve both energy efficiency and lighting performance. The aim of this study was to KEYWORDS investigate the advantages of employing a kinetic façade system and achieving a comfort Kinetic; façade; office illuminance level. A G + 7 office building was chosen as the case study for this research. DIVA- building; Dubai; lux; for-Rhino simulation software was used to determine how the proposed kinetic system was luminance; DIVA-for-Rhino integrated and compare it to the baseline case. The results show that kinetic louvers can help to achieve light levels in the range 100–300 lux, and a brightness level of 250 to 350 cd/m2. The total energy used decreased by 21.3% and the Unified Glare Rating (UGR) fell from 29.5 to below 10. In addition, Kinetic louvers achieved 100 – 300 lux and a brightness level of 250 to 350 cd/m2. Furthermore, it was found that an annual reduction of 12% occurred on the east side. More detailed analysis is provided in the paper which will help architects and designers to integrate the kinetic system in the façade of their buildings and achieve visual comfort. 1. Introduction Buildings account for nearly 40% of all greenhouse gas shown that the average energy consumption per emissions (GHGs), according to Architecture 2030. capita is 11,766 kWh and that the demand for energy A building’s capability for motion can enable it to continues to grow. For instance, Figure 1 shows that respond to various environmental conditions and per- electricity consumption by the commercial building form a variety of functions that would be difficult for sector in Dubai is very high, representing 47.55% of a static structure. In the 20th Century, interest in kinetic the total energy demand (DEWA (Dubai Electricity and architecture grew alongside a strand of thought emer- Water authority) 2017). Exterior dynamic shading ging from the Futurism movement (Fortmeyer and devices installed on “kinetic façades” can generate Linn 2014). A kinetic façade that interacts with the shaded areas on windows that vary according to the outdoor environmental surrounding it was thought shape of the shading elements and their direction of to achieve better energy efficiency and lighting com- movement. Finding a solution to lower energy con- fort (Aksamija 2013). Recent statistics in UAE, have sumption in the building sector is therefore imperative. CONTACT Hanan M. Taleb email@example.com Faculty of Engineering, British University in Dubai, PO Box 345015 Dubai International Academic City, Dubai, UAE © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of the Architectural Institute of Japan, Architectural Institute of Korea and Architectural Society of China. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 2 H. M. TALEB AND R. MOARBES Figure 1. Electricity consumption by sector in Dubai 2017 (DEWA (Dubai Electricity and Water authority) 2017). Of equal importance for office buildings is that wise supply (Formentini and Lenci 2018). Another study lighting design will make all work tasks easier. in Korea classified the kinetic façade into six types Appropriate lighting, without glare or shadows, can according to the shape (i.e., horizontal, vertical, and reduce eye fatigue and headaches; it can also prevent plane) and the movement direction (i.e., length, rota- workplace accidents by increasing the visibility of mov- tion, and aperture) of the shading elements. The ing machinery and of other safety hazards (Li and Lam shaded fractions were accurately calculated using 2001). Therefore, it is important to investigate the the positional relationships of the sun, the shading advantages of implementing a kinetic façade system device, and the window involved (Choi, Lee, and Jo and achieving a comfortable illuminance level. 2017). Further studies have proposed a reduction Consequently, the aim of this paper is to investigate factor for the shading system for various types of the advantages of such implementation and of achiev- shading devices (e.g., no shading = 1.0, internal ing a comfort illuminance level, and of the potential venetian blind = 0.5, and external awning blind = 0.4) energy reduction. (Kim and Jarrett 2011) In Algeria, researchers examined and evaluated the effect and performance of smart façades in the context 2. Literature review of indoor thermal comfort and energy efficiency. They found that the new façade system minimized exposure 2.1. Current global status of kinetic façades to direct radiation by 17.9% baseline and significantly Many international researchers have investigated the reduced energy consumption of baseline case to 43% use of kinetic façade systems, either involving real (Ben Bacha and Bourbia Oct, 2016) experiments or simulations, in order to improve the Previous research in Jordan has highlighted the architectural and energy performances of buildings substantial impact that shading devices have on the (Mahmoud and Elghazi 2016). The diversity of inno- thermal and daylight performance of offices in hot vative techniques employed could help us use less climate regions. They found that an egg-crate design energy by the middle of the 21st Century (Mawada improves the level of daylight, diagonal fins reduce and Ahmed 2015). An experimental study was con- illuminance in the morning to a low level, and vertical ducted in Italy using a rectangular planar metal plate fins to shield offices from much of the afternoon sun supported on four corners. The material used for the (Freewan 2014) panel was aluminum while nitinol was used for the Another research study conducted in Egypt wire. This provided the necessary force to open the employed a kinetic façade system in residential build- panel and to provide a sustainable façade that ings and found that this system improved and reacted to thermal variations without an energy decreased the internal temperature of the building JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 3 by approximately 2–3°C. This saved about 18–20% of 2011) of a kinetic façade system based on research, the energy used for air-conditioning in a standard simulations, and a built prototype that improves building without a shading system (Mostafa et al. upon current practice and provides an efficient 2016). façade for traditional curtain-walled office build- Finally, a team of researchers collected built ings. Another study using a simulation tool examples to assess the current state of the art in demonstrated the analysis of kinetic motion for terms of adaptive façade systems and their environ- daylight optimization at the early design stage, mental performance. They concluded that, for adap- and suggested possible configurations for daylight tive façade systems, a large amount of energy is performance (Sharaidin, Burry, and Salim 2012). required to activate the sensors and actuators. Another study (Casini 2018) stated that dynamic Ideally, this should be lower than the amount of glazing, by modulating the entry of near infrared energy saved. These aspects will have to be radiation and visible light, can lead to significant addressed to ensure the sustainability of such sys- energy savings, as well as ensuring better visual tems (Barozzi1 et al. 2016). thermal and visual comfort for building users. In a study (Jones, Hou, and Li 2015) conducted in Zurich, Chongqing and Abu Dhabi, the authors 2.2. An overview of dynamic shading tried to achieve zero carbon design in offices by integrating smart facades, ventilation, and surface The application of dynamic systems is not only exclu- heating and cooling. Many authors believe that the sive to windows. They have been utilized to enhance application of a kinetic façade system is both photovoltaic power generation (Blaifi et al. 2019). adaptive and sustainable (Barozzi et al. 2016). Windows are a crucial part of a building envelope, Although the UAE has an exemplar of a kinetic where heat exchange takes place. Many researchers façade (Attia 2016), there is a shortage of such (Zhai et al. 2019) have tried to optimize to improve research in the UAE region. Therefore, attempts the performance of windows in the building façade. have been made to fill a knowledge gap in the Automated shading systems decrease energy use and building literature. The findings will help architects improve occupant visual comfort (Colaco et al. 2008). and researchers to take action to exploit the Motorized blinds make up the majority of the systems kinetic façade system to achieve visual comfort. examined, whereas the analysis of new emerging ideas The generalizability of the research findings is pos- on deployable and foldable façade systems is limited sible and the findings may be applicable, not only (Konstantoglou and Tsangrassoulis 2016). A dynamic in the UAE, but in any country with a similar envir- shading study in Korea on a mock-up room indicated onmental and climatic context. A study (Nielsen, that, in summer, a blind slat at an angle of 30° (static Svendsen, and Jensen 2011) investigated angle) or dynamic shading is suitable for an energy Quantifying the potential of automated dynamic efficient and anti-glare control strategy (Yun, Yoon, solar shading in office buildings through inte- and Kim 2014). Another interesting simulation study grated simulations of energy and daylight, despite using the Rhino/Grasshopper environment software, the solar energy contribution, the dynamic shading helped to achieve 20–80% net energy saving by the showed a reduction of total annual energy demand use of dynamic shading compared to an equivalent of approximately 13%. Similar studies (Skarning, static system (Jayathissa et al. 2017). An experimental Hviid, and Svendsen 2017) in Rome and study of daylight glare probability in offices with Copenhagen quantified the effect of dynamic dynamic window shades concluded that simple sun- solar shading on energy, daylighting and thermal light protection strategies cannot prevent glare, comfort in a nearly zero-energy loft room, it was despite maximizing daylight utilization (Konstantzos, concluded that dynamic shading could mainly Tzempelikos, and Chan 2015). To conclude this part, improve comfort by 10–15%. Many studies have dynamic shading has a great deal of potential in hot been published on building envelopes; however, sunny regions like the UAE. It is of the utmost impor- there has been a relative lack of published tance to remember that daylight generates energy research on the use of kinetic façades in the UAE. savings by decreasing the dependence on electrical Nevertheless, one notable project in Abu Dhabi lighting, but the increase in solar energy can strain entitled “In Al Bahar Tower” explored how origami- HVAC systems and diminish occupant comfort. inspired structures obey kinematics in a manner similar to that of traditional paper-based origami, yet are also fundamentally different in that they 2.3. State of the art are typically not made of a continuous piece of material. Moreover, their relatively low rigidity has Many researchers have covered the topic under limited their widespread use as structural elements consideration in the last decade. For instance, (Suk 2019). there has been a study (Kensek and Hansanuwat 4 H. M. TALEB AND R. MOARBES Table 1. Research Variables. Base case Which is more energy efficient and has (Building as is) Research statement greater visual comfort? Levels (Building with kinetic façade) Independent Variables (1) Sun path Winter January Spring/autumn (Same sun altitude) March Summer August (2) Orientation East West South (3) Timing Morning 9 am Noon 1 pm After noon 5 pm Dependent Variables To test the performance of the Measured by lux devices and simulation façade and detect the illuminance levels 3. Methodology the independent variable. Table 1 illustrates the dependent and independent variable in this research. The process of designing a kinetic façade requires a high level of technology and a significant amount of time, including considerations regarding the design 3.1. Research approach of the external movable shading device, its operating A real office building construction was chosen as type, the real-time control of the shading elements, a baseline for this research 25°15′47″N 55°17′50″ a review of the construction of the shading device, E. A site visit was conducted to collect the required the structural stability of the shading device, and the data, including data in relation to various sorts of energy performance. Simplicity and the application of façade, building elements, architectural drawings, habi- an intelligent behavioural system is key to a successful tation arrangements, and the energy utilization profile, and effective kinetic facade. Making the right decisions values obtained for the building construction materials, and choosing the right techniques are therefore essen- glass properties, HVAC equipment, and magnitudes and tial in developing kinetic façades that serve the design schedules for occupancy, internal loads and tempera- objective (Kamil and Flora 2012) . By comparing the ture set points. This study will focus on the mechanical base case building as it is to a kinetic façade system, kinetic modification method. In the first stage, the base the study aims to determine which is more energy case was modelled and simulated. The simulation com- efficient and has greater visual comfort. The indepen- prised a single workplace area within a standard glass- dent variable is the cause. Its value is independent of façade business building. In the second stage, a kinetic other variables in this project. Whereas, the dependent louver system was proposed (see Figure 2). For the base variable is the effect. Its value depends on changes in case and the kinetic louvers, a simulation was carried Figure 2. Details of a dynamic window (Source: Author). JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 5 Figure 3. The location of the indoor and outdoor measurements with regard to the case study building. out on three selected 9-hour working days during Many authors have adopted the real measure- the year: the 15th January, the 15th March, and the ments technique with specific instruments such as 15th August. These span all four seasons as autumn is the case with this study (Bilbao et al. 2014) and spring are considered the same in terms of sun where the authors compared the measurements path and latitude. Simulations were conducted at three- of solar irradiance and atmospheric compounds hour intervals for each of the above-mentioned days, using the software package “MATLAB Corrcoef”. demonstrating the day by day functionality of each case. To validate the DIVA-for-Rhino software, real mea- In every simulation, three directions were studied: surements were taken on site on the 15th August south, east, and west. The suggested simulation techni- for the lux level and temperature, and compared que is a parametric algorithm created by coordinating with the predicted readings of DIVA-for-Rhino. The various forms of advanced simulation software includ- authors were required to obtain permission in ing Rhinoceros, Grasshopper, and DIVA-for-Rhino. The order to conduct the measurements. The device specific goal was to study the performance of the kinetic used was an Extech instrument entitled ‘CO240 envelope in offering visual comfort and in terms of for Outdoors. This device measured the exact tem- decreasing the level of energy utilization. The simulation perature and relative humidity at the case study involved building the model using Rhino/Grasshopper location. For the lux value, the authors used Extech software and then simulating illuminance ratios and 45,170 on the fifth floor, just adjacent to the win- registering the output information retrieved from DIVA- dow glazing at 12:00 noon on 2 May 2018 (See for-Rhino. Simulating the kinetic louvers involved using Figure 3) for the locations of the indoor and out- the same model in Rhino/Grasshopper, running DIVA for door test that was relevant to the case study. All different kinetic façade arrangements to determine readings were collected at 12:00 noon for the which was ideal, and then recording the outcomes in whole year, from March 2018 until March 2019. terms of illuminance and energy annual consumption. The monthly average was calculated for tempera- Three results were produced: (1) illuminance in lux; (2) ture, relative humidity and lux values. All readings luminance in cd/m and (3) the energy consumption were later compared to the readings generated by (overall building performance including the HVAC and the DIVA-for-Rhino software. Figure 4 illustrates the lighting) when outcomes were schemed for all cases. comparison between the actual measurements and Workplane illuminance was also discussed in the paper. those of the DIVA-for-Rhino software in terms of temperature (For the year of 2018). The highest discrepancy was found in the month of 3.2. Validation of the DIVA-for-Rhino software December, while other months showed minimal differences. By having another look at the month Verification and validation are the process of of September, obviously, the temperature on site checking that a piece of software meets the speci- shows 46 °C whereas it was 45 °C in the simulation fications, and that it fulfils its intended purpose. 6 H. M. TALEB AND R. MOARBES Figure 4. Discrepancy analysis of temperature ( C) between actual measurements and DIVA-for-Rhino. Figure 5. Discrepancy analysis of relative humidity (%) between actual measurements and DIVA-for-Rhino. tool. It could be argued here that the simulation the authors noticed an internal vertical blind on takes the average of 5–6 years which is why it is 1° the glazing but one which was not used at all, and C less. Having a look at Figure 5 in May, the was gathered on the sides. It is believed that it relative humidity (RH), which is the amount of partially reduced the lux. Figure 7 presents the water vapour present in the air expressed as discrepancy analysis of the cooling load per year. a percentage of the amount needed for saturation It is important to note that one neutral zone on at the same temperature, the onsite measurement the north side was then specified, and information showed 48.7% whereas the simulation suggests it retrieved from Diva-For-Rhino to calculate the was 48%. The link between the previous tempera- cooling load, and to compare this to real utility ture onsite might explain the discrepancy, with the bills. The actual utility bills were obtained directly one C increasing the RH by enhancing the eva- from the owner who shared the Dubai Electricity poration. Figure 6 shows the discrepancy analysis and Water Agency DEWA bill of one year from of the illuminance reading. The actual illuminance January 2018 till December 2018 for the whole of nd on site reading in March was 790 lux, where it is 38 the 2 floor. Notably, the highest discrepancy was lux less in the software. By observing the office, found in the month of June, with the over- JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 7 Figure 6. Discrepancy analysis of illuminance (lux) between actual measurements and DIVA-for-Rhino. Figure 7. Discrepancy analysis of cooling load (kWh) between actual measurements and DIVA-for-Rhino. dependence on the HVAC system being the main that there were fewer errors than expected, and reason. By having informal interviews with the that it will provide accurate results. All Figures 6–9 employees, it turned out that they bought 5 extra contain tables of the actual measurements and the air-conditioning indoor units which they placed predicted data of the software as well as the dif- next to their desks. The overall discrepancy ferences, the dotted line between the columns between the actual measurements and the soft- represents average trendline which evens out fluc - ware suggest that the software is reliable, that tuations in data to show a pattern or trend more there were fewer errors than expected, and that clearly. All Figures 6–9 contain tables of the actual it will provide accurate results. On the other hand, measurements and the predicted data of the soft- this paper attempted to take the measurement for ware as well as the differences, the dotted line the whole month and the average was calculated between the columns represents average trendline then compared against the software. The overall which evens out fluctuations in data to show discrepancy between the actual measurements and a pattern or trend more clearly. Figure 9 illustrates the software suggest that the software is reliable, the actual cooling load and not average, however, 8 H. M. TALEB AND R. MOARBES Figure 8. Kinetic Façade modelling for 90, 75, 60, 45, 30, and 15-degree folding. the discrepancy indicates that the software is accu- Glare Rating or UGR which has the following rate and will predict the results accurately. The equation: weather input of the software was used for this � � �� 0:25 L ω simulation. UGR¼ 8 log L = Background luminance in cd/m , calculated from 3.3. Mathematical set-up Eind/π with Eind as the vertical indirect illumination at 3.3.1. Unified glare rating the observer’s eye. It is important to note that glare occurs solely when L = the sum of light luminance, in cd/m of the light- the eye is exposed to the luminous element of emitting surface of each light in the direction of the a luminaire. When this occurs, the amplitude of the observer’s eye. glare can range from barely noticeable to extremely ω = the sum of the solid angle from the viewer’s line discomforting and can be quantified by the Unified of sight. Table 2. Base Case “lux” Performance – East Direction. East direction 9:00 am 1:00 pm 5:00 pm 43% > 2000 lux 0% > 2000 lux 0% > 2000 lux 37% > 2000 lux 6% > 2000 lux 0% > 2000 lux 33% > 2000 lux 10% > 2000 lux 0% > 2000 lux 15 August 15 March 15 January JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 9 Table 3. Base Case “lux” Performance – West Direction. West Direction 9:00 am 1:00 pm 5:00 pm 0% > 2000 lux 0% > 2000 lux 69% > 2000 lux 0% > 2000 lux 3% > 2000 lux 76% > 2000 lux 0% > 2000 lux 8% > 2000 lux 76% > 2000 lux Table 4. Base Case “lux” Performance – South Direction. South Direction 9:00 am 1:00 pm 5:00 pm 24% > 2000 lux 25% > 2000 lux 13% > 2000 lux 8% > 2000 lux 16% > 2000 lux 12% > 2000 lux 7% > 2000 lux 12% > 2000 lux 2% > 2000 lux p = the Guth/ position index depending on their indicated high visual discomfort. For this study glare spatial deviation from the main line of sight. was calculated for a single orientation at a single posi- The UGR values are in the range of 10 (“no glare”) to tion. The following section will present the lux perfor- 30 (“unacceptable discomfort glare”). The larger the mance after a kinetic façade system was integrated UGR value, the greater the probability of glare. These that responded to the path of the sun. limits are assigned to specific activities and space func- tions, and must not be exceeded (evo.support 2017). 3.3.2. Light level or illuminance The UGR was manually calculated for the zone, and Illuminance is the total luminous flux incident on the average for the base case UGR was ≥29.5, which a surface per unit area. The area – the work plane – is 15 August 15 March 15 January 15 August 15 March 15 January 10 H. M. TALEB AND R. MOARBES Table 5. Kinetic Louver “lux” Performance – East Direction. East direction 9:00 am 1:00 pm 5:00 pm o o o 11% > 2000 lux 45 0% > 2000 lux 90 0% > 2000 lux 90 o o o 9% > 2000 lux 60 0% > 2000 lux 90 0% > 2000 lux 90 o o o 4% > 2000 lux 60 0% > 2000 lux 90 0% > 2000 lux 90 Table 6. Kinetic Louver “lux” Performance – West Direction. West Direction 9:00 am 1:00 pm 5:00 pm o o o 0% > 2000 lux 90 0% > 2000 lux 90 16% > 2000 lux 30 o o o 0% > 2000 lux 90 0% > 2000 lux 90 8% > 2000 lux 30 o o o 0% > 2000 lux 90 2% > 2000 lux 90 9% > 2000 lux 30 where the most important tasks in the room or space Φ = luminous flux – the quantity of light emitted by are performed. a light source (lumen, lm) Illuminance can be expressed as A = area (m ) According EN 12464 light and lighting (CIBSE 2017) – E ¼ Φ=A lighting of workplaces -indoor work places, the minimum illuminance is 50 lux for walls and 30 lux for ceilings. where Earlier it was common to have light levels in the range E = illuminance (lm/m , lux) 100–300 lux for normal activities. Today the light level is 15 August 15 March 15 January 15 August 15 March 15 January JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 11 Table 7. Kinetic Louver “lux” Performance – South Direction. South Direction 9:00 am 1:00 pm 5:00 pm o o o 8% > 2000 lux 60 4% > 2000 lux 60 10% > 2000 lux 45 o o o 0% > 2000 lux 90 4% > 2000 lux 90 0% > 2000 lux 90 o o o 0% > 2000 lux 90 2% > 2000 lux 90 0% > 2000 lux 90 Table 8. Comparison of Luminance between Base Case and Kinetic Louvers. East Direction West Direction South Direction Ti 9:00 am 1:00 pm 5:00 pm me more commonly found in the range 500–1000 lux – on one floor. The floor covers an area of 1765 square depending on the activity. For precision and detailed meters in which a closed office of 7.7 m x 11.9 m dimen- work, the light level may even approach 1500–2000 lux. sions is located. The office room is covered with a glazing curtain wall with no shading system being implemented. (1) Case study The height of the floor is 3.5 m from slab to slab. The office building is located on Sheikh Zayed road in Dubai. The principal façade of the building faces in 3.4. Modelling a westerly direction towards Seaview (West Direction). The design factors and characteristics of the base Within the building there is a ground floor with model were assigned and defined as follows: infil - a mezzanine and 6 typical floors with a plot area of tration of air per hour was 0.5. The occupancy level approximately 3674 square meters. The building is typical for the office was 10 m /occupant, the minimum of the design for an 8-story office building of similar level of light was 300 lux, and the indoor tempera- height. The research focuses on a single module located ture was fixed at 23 °C. The prototype office room Kinetic Louvers Base Case 15 August 15 March 15 January 12 H. M. TALEB AND R. MOARBES Table 9. Workplane illuminance level of office zone in the Base Case (static shading at 90°) on South th Façade on 15 August without artificial lighting. Figure Angle Mean Without artificial lighting Rendering & workplan Hour e illuminan ce ( lux ) 90 307 Base case 8:00 am 90 453 10:0 am 90 605 12:0 pm 90 595 1:00 pm 90 481 3:00 pm 90 297 5:00 pm modelled for a volume of 7.7 m x 11.9 m x 3.5 m 4. Results and findings was located within the three sides of the building 4.1. Base Case lux Performance as mentioned above. Hence, the simulation was systematically generated for the three facades. In terms of the east side at 9:00 am in the morning for all The nine working hours from Sunday to Thursday seasons, the performance of the zone shows a high value were 8:00am to 6:00pm. The louver configuration of 420 lux due to the sunrise (Table 2). It is important to began at an angle of 90° and was then reduced to note that solar radiation in the UAE is significant, and angles of 75°, 60°, 45°, 30°, 15° and 0° (the latter is a total of 3568 average annual solar hours corresponds to full shading, meaning full obscurity). Figure 8 sum- an average annual solar radiation of approximately 2285 marizes the details for all scenarios. kWh/m . At 1:00 pm the illuminance typically began to JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 13 Table 10. Workplane illuminance level of office zone in the Base Case (static shading at 90°) on South th Façade on 15 August with artificial lighting. Figure Angle Mean With artificial lighting Rendering & workplane Hour illuminance ( lux ) 90 598 Base case 8:00 am 90 711 10:0 0 am 90 876 12:0 0 pm 90 853 1:00 pm 90 746 3:00 pm 90 572 5:00 pm spread, and at 5:00 pm the light illuminated the zone 4.2. Kinetic façade with different louver more dimly during all seasons. Conversely, on the west inclinations side (Table 3) the lux value gradually increased, reaching The results indicate that the excess light decreased as high as 400 lux. The highest values were recorded in dramatically, which reduced thermal gain and thus January at 5:00 pm due to the lower position of the sun in the dependence on air-conditioning in the office. the sky which extended the light inside the zone. For the Regarding lux performance, Table 5 shows that the south side (Table 4), there was a relatively improved configuration used to reduce the illuminance level uniformity ratio inside the zone, where the highest con- over 2000 lux was 45 degrees (see Figure 2 again). th th trasts being on 15 January at 9:00 am and 15 August at With this configuration, the illuminance level over 5:00 pm. 2000 lux was reduced from 26% to 11%. Although A comparison of Tables 2 and 3 shows that the East this can be reduced further to 5% with a 90-degree and West side at 9:00 am has much greater exposure to louvre configuration, this may not be ideal due to the the sun as it is 24% higher than in the west (where is reduction of sunlight and the subsequent increase in almost 0% in January). In the same month, large differ - the need for artificial light, which increases the ences were also evident at 5:00 pm. For instance, the demand for power. In the west direction (Table 6), lux level dropped by 2% at 5:00 pm, whereas in the the kinetic façade initially worked strongly and clearly west the percentage jumps to 76%. during the afternoon. The proportion of spaces 14 H. M. TALEB AND R. MOARBES th Table 11. Workplane illuminance level of the office zone with kinetic folding on South Façade on 15 August without artificial lighting. Figure Angle Mean Without artificial lighting Rendering workplan Hour illuminan ce (lux) 15 7.5 8:00 am 30 82 10:0 am 90 605 12:0 pm 45 200 1:00 pm 60 224 3:00 pm 75 177 5:00 pm covered by an illuminance level over 2000 lux fell from 4.3. Comparison of luminous intensity between 64% to 16%. This could be reduced to zero percent base case and kinetic louvers with an angular configuration of 15 degrees; however, Luminance is a photometric measure of the luminous natural light is recommended to minimise power con- intensity per unit area of light travelling in a given sumption. In the south direction (Table 7), the kinetic direction. It describes the amount of light that passes façade had only a slight impact, as less than 10% of through, is emitted, or is reflected from, a particular spaces were covered by an illuminance level of more area, and falls within a given solid angle. Selected for th than 2000 lux. For the south side during January, the this purpose are the lux performance on 15 August at th louvre angle was maintained at 60 to 45 degrees 9:00 am from the east direction, 15 March at 5:00 pm th throughout the day. Because the best practice for from a west direction, and 15 January at 1:00 pm (Suk 2019) workplace offices should be an average from a south direction. Table 8 presents the results in level within 200 lux, the kinetic façade therefore mod- terms of luminous intensity performance with the cd/ erated the lux level while reducing the glare. m units. Based on the Table 8, the luminance value reduced especially at 9:00 am and 1:00 pm, this mini- Furthermore, an average UGR < 10 (Mushtaha et al. mised the variation which indicates low contrast and 2022) represents an improved reading compared to helped to achieved uniformity ratio of light the base case (See Tables 9,10,11,12). JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 15 th Table 12. Workplane illuminance level of the office zone with kinetic folding) on South Façade on 15 August with artificial lighting. Figure Angle Mean With artificial lighting Rendering workplane illuminance Hour (lux) 15 359 8:00 am 30 435 10:00 am 90 876 12:00 pm 45 550 1:00 pm 60 570 3:00 pm 75 526 5:00 pm distribution which also indicates better visual comfort. artificial lighting (See Table 9). The second scenario Studies (Suk 2019) stated that for the background was to test the workplane in the base case with static lighting on the walls the maximum luminance should horizontal shading at an angle of 90° with artificial be limited to 1000 cd/m a luminance on the ceiling of lighting (See Table 10). The third scenario was to test the work plane with kinetic shading at different angles 250–500 lux is perceived as comfortable, this means without artificial lighting (See Table 11). The fourth the kinetic case is much better than the base case. scenario was with kinetic shading at different angles with artificial lighting (See Table 12). Other angels 4.4. Comparison of workplane illuminance represent the angles of the kinetic movement. They were manually introduced in the simulation each case Workplane is defined as a horizontal plane located at will represent the performance of angel specified. The the nominal working height in an interior space. highest mean workplane illuminance was recorded at Daylight factors and illuminance measurements and an angle of 90° at 12:00 pm in the second scenario and calculations are made for points on this plane in fourth with a reading of 876 lux and 853 lux at 1:00 pm order to provide visual comfort for the workers. The 15 August 2018. These readings indicate that artificial height of the workplane (desk) is 0.85 m in the base lighting is not needed as it might cause glare. Another case, which matches European standards. The first scenario was test the workplane in the base case with point worth noticing was that the kinetic shading static horizontal shading at an angle of 90° without helped to moderate the high fluctuations. 16 H. M. TALEB AND R. MOARBES Figure 9. Annual Energy Consumption before and after application of the kinetic louver system. The base case (Table 9) shows that at 9:00 am in 5. Discussion an east direction, the intensity reached 1900 cd/ Figure 9 indicates that the main factor affecting the m , which was reduced by 45% using kinetic lou- overall energy used is the cooling energy in UAE. One vers (same table). The uniformity ratio was weak zone was taken from East, West and South directions. due to the high contrast. The discrepancy was The Energy consumption was calculated before and more significant in the west direction where after applying the kinetic shading. The total energy 1900 cd/m luminance occupying 50% of the consumption of base case of East zone was 12,361 whole zone fell dramatically with the kinetic lou- 2 kWh. The total energy consumption of base case of vers providing luminance between 100–300 cd/m . West zone was 11,430 kWh and finally the energy The glazing of the south direction in the base case consumption of base case of South zone was 11,315 offered a brightness of 700–900 cd/m with the kWh. After apply the kinetic shading, the total energy kinetic louvers. Typical brightness ratings ranged consumption of kinetic case of East zone was 10,867 from 250 to 350 cd/m for monitors that per- kWh which means that kinetic shading helped to formed general-purpose tasks. This was especially reduce the energy by 12%. The total energy consump- obvious in the south direction at 5:00 pm with the tion of kinetic case of West zone was 11,039 kWh which kinetic louvers. JOURNAL OF ASIAN ARCHITECTURE AND BUILDING ENGINEERING 17 means that kinetic shading helped to reduce the considered too lit and might cause a glare. It is there- fore concluded that kinetic louvers can help to achieve energy by 3.5%. Lastly, the total energy consumption light levels in the range of 100 to 300 lux, and of kinetic case of South zone was 10,664 kWh which a brightness level ranging from 250 to 350 cd/m . means that kinetic shading helped to reduce the Moreover, the total energy can be decreased by energy by 5.8%. These results indicated that the East 21.3% and the Unified Glare Rating (UGR) can be and probably the South elevations have a priority of made to fall from 29.5 to below 10. The limitation of implementing the kinetic shading. Whereas, the West this study is focusing on one type of building with has the least priority due to low benefits. The overall specific region. It is recommended as future research total reduction in annual cooling energy from the base to include different type of building with different case of the three zones could reach to 21.3 %. The climatic contexts and regions. Vertical shading is also kinetic shading did not contribute that much to future research recommendation. lower the equipment energy at all in South direction, but it lowered the equipment energy by 10% in East direction and by 1.5% than the base case. In the next Disclosure statement section, a reflection of the work done will be demon- No potential conflict of interest was reported by the strated. Back to section 2.3, a study (Nielsen, Svendsen, author(s). and Jensen 2011) that managed to lower the energy consumption by 13%, this study managed to do better reduction by 8.3%. However, the study of the Abu Notes on contributors Dhabi case (Kamil and Flora 2012) where they lowered Hanan M. Taleb is a professor in Sustainable Design of Built the energy demand in West direction by 25.2%, this Enviroment at the British University in Dubai, UAE. Her study couldn’t reach this reduction. This might due to reserch interest includes passive design, sustainable urban the height of the two case buildings, the Abu Dhabi deign and building evelope design. case is high rise building where this study is only G + 7. Rudy Moarbes has Masters of sustainable Design of built This indicates that the kinetic shading potential enviroment, faculty of Engineering at the British University increase with the increase of the building height. in Dubai, his reserch interest is Facade systems. 6. Conclusion References Many new genres of kinematic architecture are now Aksamija, A. 2013. Sustainable Facades. Design Methods for high-performance Building Envelopes. Bognor Regis: John emerging. 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Journal of Asian Architecture and Building Engineering
– Taylor & Francis
Published: Sep 3, 2023
Keywords: Kinetic; façade; office building; Dubai; lux; luminance; DIVA-for-Rhino