Room Dimensions Research Articles

Dynamic analysis of office lighting smart controls management based on user requirements

Daylight dynamic metrics provide an alternative approach for the assessment of the energy savings promoted by lighting control systems. This research aims to quantify the energy savings allowed by lighting smart controls using continuous and overcast daylight autonomy, novel metrics tested monitoring a mesh of illuminance-meters in test cells over a one-year period. Three types of smart controls are proposed, based on switches and dimmers, some of which were managed by illuminance-meters and irradiance detectors. Energy savings are assessed according to weather data, room dimensions, inner reflectances, window size and user requirements—illuminance needs and working hours. The results show a reduction in the average energy consumption of electric lighting of up to 23%, suggesting the suitability of the smart controls proposed. Smart controls without illuminance-meter feedback are only recommended for shallow rooms with low requirements, while dark deep rooms demand a complex dimming system managed by external illuminance-meters.

Modeling a representative room to evaluate sound power measurement methods for ASTM ISR testing

ASTM ISR (Impact Sound Rating) test method suffers from non-reproducibility problems, especially in lower frequency bands in smaller rooms where the sound field is non-diffuse. The problem arises from the fact that Sound Pressure Level is measured in these rooms, which is dependent on the room dimensions if the sound field is non-diffuse due to low modal density. Currently, this non-diffusivity is ignored. We propose to measure sound power radiated from the ceiling instead of volume-averaged sound pressure level, which is independent of room dimensions regardless of the type of sound field in the receiving room. This study evaluates sixteen different ideas to measure sound power levels in the receiving rooms through a simulation model of a representative room using Simcenter 3D. Each method's pros and cons in the simulation are used to downselect methods to test in the field.

A Numerical Study on Indoor Air Quality (IAQ) Designs for Hospital Waiting Room in The Context of COVID-19 For Hot and Warm Humidity Climate

COVID-19 is a virus originated from Corona Virus which can severe acute respiratory syndrome (SARS) symptoms such as chest pain, dry cough, fever, and difficulty breathing. The AC and ventilation system is not only important for the thermal comfort occupants but to ensure the room is safe and free from infectious virus. Thermal comfort is important measurement in indoor space which influenced by temperature, Relative Humidity (RH), airflow velocity and others. This research was executed and focused on lecture room in Bilik Persatuan 10, Universiti Malaysia Perlis (UniMAP) instead of real hospital waiting room. It comes with the room dimensions 11.87m (Length) × 5.17m (Width) × 2.93m (Height) for the numerical study. In addition, Computational Fluid Dynamics (CFD) analysis is used to investigate the air flow pattern and temperature distribution inside the room. By using software Ansys FLUENT 19, field experimental and simulation work can be compared which have 14.55% difference in temperature distribution. It is expected by increasing the air velocity of the AC inlet diffuser influence the pattern of airflow in the room, but average temperature remains same for all these conditions.

Optimum external shading system for counterbalancing glare probability and daylight illuminance in Sydney's residential buildings

PurposeOptimisation of daylight admission through window is crucial for alleviating glare while maintaining useful daylight levels in order to enhance occupants' health, visual comfort and moderating lighting energy consumption. Amongst various solutions, fixed external shade is an affordable solution for housing spaces that need to be sophisticatedly designed, especially during the period of increasing home spaces as working environments. In the humid subtropical region, daylight control plays an important role in indoor comfort, particularly with areas with a high window to wall ratio (WWR). Due to the insufficient amount of such study on non-office spaces in Australia, shading-related standards are not addressed in Australian building codes.Design/methodology/approachThe chosen methodology for the research is a quantitative data collection and analysis through field measurement and simulation simultaneously. The first step is a multi-objective optimisation of shading elements through a non-dominated sorting genetic algorithm (NSGA-II) on parametric modelling via Rhino3D CAD and simulation engines (DIVA and ClimateStudio). In the second phase, the Pareto front solutions are validated by experimental measurements within a room with a single north-facing window (the most probable for the daytime glare in Sydney) for the seven most common local window configurations.FindingsThrough the simulation of ten genes, 1,560 values and 2.4 × 1,019 of search space, this study found an optimum shade for each local common window layout, resulted in +22% in (UDI) and −16% in views with discomfort glare on average. Moreover, an all-purpose polygonal shade showed an average of 4.6% increase in UDI and a 5.83% decrease in the percentage of views with discomfort glare.Research limitations/implicationsThe findings are subject to the room dimensions, window dimensions and layouts, and orientation of windows for selected residential buildings in Sydney.Originality/valueThe study contributes to the development of highly accurate fixed external shading systems with rectangular and tapered-form external shapes. A real-time measurement by luminance-metre sensors and HQ cameras located at six eye levels is conducted to corroborate simulation results of the visual comfort.

A Simulation Analysis of LEDs’ Spatial Distribution for Indoor Visible Light Communication

Visible light communication (VLC) is a promising technology that can jointly be used to accomplish the typical lighting functionalities of the light emitting diodes (LEDs) and data transmission, where light intensity is modulated with the aid of a high rate data that cannot be noticed by the human eye.qu In this paper, a VLC simulation framework to study the effect of LEDs’ distributions on different room dimensions is proposed by considering the performance metrics such as light intensity quality in accordance with the International Organization for Standardization (ISO) recommendation, and data transmission efficiency measured in terms of bit error rate (BER). To achieve that, a VLC communication system is designed that modulates the data, transmits it over the room utilizing the communication channel that is modeled using an accurate ray-tracing algorithm, and receives it. Our work is different from most of the published works, which studied either the data transmission efficiency or lighting quality but not both. In addition, our study investigates the effect of having different rooms dimensions and different number of transmitters on data transmission quality and light illumination. Consequently, this paper can be used as a methodological study to design an efficient VLC system that satisfies the ISO lighting requirement and the VLC application-specific BER requirements. Furthermore, a video transmission use case has been demonstrated, which shows how video quality can be significantly improved when the number of transmitters is increased. However, considering the ISO lighting requirements, one can put a limit on the number of LEDs that can achieve the required application BER and lighting requirements, thus achieving both objectives efficiently.

Re-evaluation acoustic quality in lecture halls using G and C50: University of Sharjah Case Study

In our previous studies, we focused on the common approach of measuring Reverberation Time (RT) for assessing acoustic quality in various types of lecture halls at the University of Sharjah (United Arab Emirates). The absorbing surfaces at the lecture halls at the University of Sharjah are limited to one surface (hanging ceiling), which has been shown in the literature to affect the accuracy in the description of the acoustic response as a result of the introduced uncertainty in the measured reverberation times. Because of these reasons, it has been highlighted in the literature that RT is considered not a good predictor of acoustic quality, namely speech intelligibility, in the lecture halls. Therefore, additional acoustic parameters need to be measured of calculated to accurately predict the acoustic response in lecture halls, especially speech intelligibility during activities that takes place within the lecture hall. The focus of our current research is to extend our precious work on RT to calculate additional acoustic parameters, namely the acoustic strength, G, and the speech clarity, C. Our goal is to investigate the practical use of G and C to describe acoustic response in the examined lecture halls. In addition to special variations with frequency, we will examine the effects source position, room dimensions at different locations within the lecture hall. The measurements were conducted in the same lecture halls under the same conditions including the acoustic absorbers and sound diffusers, which have shown to influence measured acoustic parameters. The results were compared to standards for the purpose of providing recommendations for range of acoustic parameters to support adequate speech communication during various teaching and learning activities in lecture halls.

Employing DIALux to relieve machine-learning training data collection when designing indoor positioning systems.

We propose and demonstrate using the DIALux software with our proposed linear-regression machine-learning (LRML) algorithm for designing a practical indoor visible light positioning (VLP) system. Experimental results reveal that the average position errors and error distributions of the model trained via the DIALux simulation and trained via the experimental data match with each other. This implies that the training data can be generated in DIALux if the room dimensions and LED luminary parameters are available. The proposed scheme could relieve the burden of training data collection in VLP systems.

Housing Spaces in Nine European Countries: A Comparison of Dimensional Requirements.

Modern housing units must meet new needs and requirements; housing dimensions and functional characteristics are relevant issues, mainly considering population ageing and disability. The housing standards of nine European countries were compared to analyze their ability to satisfy new population need, in terms of size. The regulations were downloaded from the websites of the official channels of each country. A wide variability in room size was observed (e.g., single room: from 9 m2 in Italy to 7 m2 in France, to the absence of any limit in England and Wales, Germany-Hesse, and Denmark). Italian and French legislations define housing dimension considering the room destination and the number of people. The Swedish regulation provides performance requirements and functional indications but does not specify the minimum dimensions of habitable rooms. The rooms’ minimum heights vary between 2.70 m in Italy and Portugal and 2.60 m in the Netherlands, but no limits are established in England and Wales. A diverse approach among European countries regulations is observed: from a market-oriented logic one (e.g., England and Wales) in which room minimum dimensions are not defined to a prescriptive one (Italy) and one that is functionality-oriented (the Netherlands). However, considering the health, social, environmental, and economic trends, many of these standards should be revised.

Performance analysis of R290 as a substitute for R404A on 12,000 Btuh cold storage capacity

Cold Storage is a machine that has a very low temperature:-30°C which is used for the freezing process. Cold storage used for this research has a capacity of 18,000 Btuh with R404A. This refrigerant does not contain ODP but still contains a very high GWP: 3940 compared to R290. R290 (propane) is GWP:4 and ODP:0. But this refrigerant has flammable properties between LFL-UFL: 2-10%. The cold room dimensions: 3 x 1.5 x 2.5:11.25m3. The testing methodology by comparing the performance of R404A with R290 cold storage conditions was tested without using a cooling load with a room temperature setting of -29°C, room temperature of 35°C and RH: 70%. Time Testing is carried out for 90 minutes. From the test results obtained data: evaporator temperature: -29°C with a time of 68 minutes for R290 and 95 minutes for R404A, LP: R404A / R290: 12/6 Psig, discharge pressure: 215 / 175 Psig and the amount of refrigerant entered in the system: 3500/1800 grams and electric current: 4.1/2.9 Amperes. From the data analysis, it can be concluded that R290 has better performance, energy-saving, and environment friendly compared to R404A.

Experimental Study of the Effect of Confining on the Development of Fire in a Closed Compartment

Backdraft is a complex phenomenon which occurs during cases of confined fires. It appears by a fast deflagration which occurs after the introduction of oxygen into a compartment filled with hot gases rich in unburned combustible vapor. Practically, this situation could occur at the time of intervention of firemen who break the door or when a window breaks under the action of thermal stresses. Based on a strong experimental campaign, the present paper aimed to make a quantitative investigation of the effect of confining on a totally closed fire. With this focus, fire tests were carried out in a completely closed room of dimensions 1.20 m × 1.20 m × 1.02 m, with five sources of fire of different heat release rates. The same fire sources were also tested in a free atmosphere in order to get reference data. After a statistical study of data, a comparative analysis between both results has been done. Its outcome is that confining has a major impact on the quality of combustion and on the fire duration. More precisely, it has been noticed comparatively to fire tests in free atmosphere that confining increases the fire duration by 14.85 percent while it decreases the heat release rate by 21.72 percent.

Geomechanical justification of room-and-pillar dimensions for rock salt and polymineral salt mining

The key target of room-and-pillar planning for mining rock salt, polymineral salt and polyhalite at the minimized loss of minerals in pillars is optimization of the dimensions of rooms and rib pillars. The authors compare some variants of mining with rooms and rib pillars, as well as with honeycomb mine structure. The theoretical and experimental studies prove efficiency of room-and-pillar dimension optimization by combination of analytical estimation with numerical analysis and physical modeling of the stress–strain behavior of underground structures (honeycomb mine structures). It is found that the honeycomb mine structures feature higher resistability of structural components to external loads. The research into secondary stress field generation and influence on structural elements of the roomand- pillar mining systems made it possible to calculate stable parameters for the conventional and innovative mining systems. The study was supported by the Russian Science Foundation, Project No. 19-17-00034.

Modelling the Effects of Boundary Walls on the Fire Dynamics of Informal Settlement Dwellings

Characterising the risk of the fire spread in informal settlements relies on the ability to understand compartment fires with boundary conditions that are significantly different to normal residential compartments. Informal settlement dwellings frequently have thermally thin and leaky boundaries. Due to the unique design of these compartments, detailed experimental studies were conducted to understand their fire dynamics. This paper presents the ability of FDS to model these under-ventilated steel sheeted fire tests. Four compartment fire tests were modelled with different wall boundary conditions, namely sealed walls (no leakage), non-sealed walls (leaky), leaky walls with cardboard lining, and highly insulated walls; with wood cribs as fuel and ISO-9705 room dimensions. FDS managed to capture the main fire dynamics and trends both qualitatively and quantitatively. However, using a cell size of 6 cm, the ability of FDS to accurately model the combustion at locations with high turbulent flows (using the infinitely fast chemistry mixing controlled combustion model), and the effect of leakage, was relatively poor and both factors should be further studied with finer LES filter width. Using the validated FDS models, new flashover criteria for thermally thin compartments were defined as a combination of critical hot gas layer and wall temperatures. Additionally, a parametric study was conducted to propose an empirical correlation to estimate the onset Heat Release Rate required for flashover, as current knowledge fails to account properly for large scale compartments with thermally thin boundaries. The empirical correlation is demonstrated to have an accuracy of ≈ ± 10% compared with the FDS models.

Actual Visual Acuity Demands in the Classroom

Purpose: To address the knowledge gap regarding the actual acuity requirements needed in typical kindergarten through grade 12 classrooms by determining an actual logarithm of the minimum angle of resolution (logMAR) and contrast sensitivity requirements in a sample of classrooms for kindergarten through grade 12 in New York City. Methods: Measurements of classroom dimensions with specific attention to viewing distances were made in public and private school classrooms, at various grade levels from kindergarten through grade 12, in New York City. The dimensions of typical text shown to students on classroom smartboards and whiteboards was measured and the mean and range of logMAR values were calculated for various seating locations within the classrooms. Contrast between text and background was estimated by comparing digital images of actual classroom text to Pelli-Robson contrast sensitivity charts. Results: Fourteen classrooms in five schools were evaluated. Classroom dimensions varied from 8 × 10 feet to 23 × 23 feet. Mean logMAR values of lower case text on smartboards and whiteboards varied from 0.93 ± 0.29 (range: 0.83 to 1.32) in the center of the front row to 0.46 ± 0.21 (range: 0.10 to 0.79) in the center of the back row ( P < .001). Contrast was also variable, being highest for black markers on whiteboards (0.00) and lowest on smartboards (0.15 to 0.60). Neither logMAR nor contrast sensitivity values varied significantly by grade level or school ( P > .50 for both). Conclusions: The data reveal that logMAR demands and contrast vary substantially from classroom to classroom and within a classroom based on room dimensions and seating. Although generally supporting current acuity-based pediatric vision screening referral guidelines, the data also provide insight into the potential impact of reduced visual acuity and seating location on visual performance in the classroom. These findings suggest the need to develop logMAR and contrast standards that optimize visual content in classrooms while accommodating a wider range of visual capabilities. [ J Pediatr Ophthalmol Strabismus . 2021;58(1):48–54.]

Energy Saving Analysis for Mud Wall Construction

In building construction, the energy saving is very important for coming day. Energy saving is closely related with conservation of energy. The consequences of conservation of energy related to efforts reduce to consumption of energy. A certain amount of energy may be saved , when critical thickness of insulation is used in building walls. The purpose of thermal insulation is to keep the indoor temperature constant due to variation of atmospheric temperature. The main aim of mud wall construction is to save considerable amount of energy by providing a more stable temperature and reduces the heat losses through outer boundary of walls. Mud is act as a thermal mass due to it absorbs sun heat during day hours and keep the building warm during night. The energy saving by using mud insulation and straw material for the analysing the mud wall constructed room dimension (10 m x 8 m x 7 m) situated at Ghaziabad near Salimar Garden has been selected. The studies are carried out for varied thickness of insulation mud dung slurry. This study found that mud wall insulation is most economic insulation. In this analysis, it is observed that 51 % of energy is conserved by the application of mud dung slurry insulation for mud wall construction. In our result, 0.068 m optimum thickness of mud wall construction has been calculated, when insulation is used.

Potential and control method of bioaerosol emission at composting process in TPST Diponegoro University

Laboratories in university particularly related to biological process have the potential to emit bioaerosol. The composting process in the lab is one of those that produce complex bioaerosol. This study is aimed at analyzing the potential bioaerosol emissions from the composting process at TPST and proposing efforts to reduce emissions toward outside the lab room. To calculate the emission potential of bioaerosol, specific emission factors from the literature are used.The room dimensions for composting are 2.46 x 1.38 x 0.7 m, and there are 18 spaces for the composting process. Based on the the measured dust concentration in the composting room were on average above the ambient air quality standard for TSP (230 ug/m3). Hypotetically, emissions from the composting process at TPST reach a highest point of 4x106 CFU/m3, peak at a distance of 7 m from the source of the composting process. However, the health risks associated with bioaerosol emissions are relatively small because the period of exposure to TPST operators near the composting area is quite small. Control efforts by installing a windbreak fence can minimize the amount of emissions that leave the composting area by 80%.

Light Wave Propagation Model for Indoor Visible Light Communication Systems Employing Small LED Sources

The aim of the present work is to build a robust and computationally efficient model for the light wave propagation in indoor visible light communication (VLC) systems. It is assumed that a small (point) LED source is used inside a room of relatively small dimensions (room area ≤ 5m × 5m). The light wave is treated as an electromagnetic wave suffering multiple reflections on the walls of the room. The Geometrical Theory of Diffraction (GTD) is applied for evaluation of the light wave reflection on the rough walls of the room. Also, the present work is concerned with developing a new computational method for the assessment of intersymbol interference (ISI) encountered in such indoor VLC systems. The signal strength, the power of ISI, and hence, the signal-to-ISI ratio (SISIR) are evaluated over the horizontal plane of the mobile units (at a height of about 1m above the room floor). The effects of the room dimensions and some structural parameters such as the reflectance of the side walls on the SISIR are numerically investigated.

DEVELOPING A SPACE SYNTAX-BASED EVALUATION METHOD FOR PROCEDURALLY GENERATED GAME LEVELS

Procedural content generation (PCG) has been an essential catalyzer in the last decade with its efficiency in creating game elements such as textures, game levels, and maps. Despite being successfully applied in various studies, new reliable evaluation tools are still needed to assess the quality of the generated game content. One example limitation of procedurally generated game worlds is the lacking spatial configuration. To address this issue, in this study, an assessment method was developed to evaluate the spatial quality of procedurally generated game worlds. For this purpose, Space Syntax was used, which incorporates a set of methods to analyze spatial configurations and movement. The analyses were applied to a new game developed by the authors —the Haunted House— and the performance was evaluated in terms of integration, connectivity, and depth distance. Results show that changing the room dimensions (i.e., 15x15, 25x25, and 35x35 units) modifies the performance measures as well as game design parameters —number of the spawning points (ranging from 1 to 4), critical axes (1 to 5), to name a few. The proposed approach is a first attempt to create various improved spatial configurations and provide an evaluation tool to analyze the PCG algorithms in level design.

Airflow and thermal comfort evaluation of a room with different outlet opening sizes and elevations ventilated by a two-sided wind catcher

Wind catchers as passive cooling systems contribute to the enhancement of air quality, thermal comfort, and reduction of energy consumption in the residential sector. In this paper, the indoor flow structure, crossflow ventilation characteristics, and thermal comfort of a room integrated with a two-sided wind catcher is numerically investigated. A mixed-climate condition and experimentally validated room dimensions are utilized to define the physics of the problem. 3D steady-state RANS CFD simulations, with different turbulence models for a reference case are simulated, and their performance is compared with the published literature. The following analyses are conducted based on a validated SST k-ω model and a fixed reference case dimensions with (1) five different room outlet elevations (top, reference case, middle, front of room inlet opening, and floor) and (2) four different outlet areas to the wall ratio (10%–40%). The results show that the room outlet mass flow rate increases up to 26% by decreasing the room outlet elevation from the top to the floor; the front and floor outlet elevations obtained the optimum thermal comfort metrics. At a specific room outlet opening elevation, increasing the room outlet area to wall ratio increases the mass flow rate; the 30% aspect ratio obtained the desired temperature stratification and velocity field. These results can be combined with architectural metrics towards improving user comfort in the buildings.

Ventilation performance of a naturally ventilated double-skin façade in buildings

Using a double-skin facade for natural ventilation is not a new idea, but the behind mechanism and impacts of those environmental and designing factors on its performance are still unknown and critically needed. Therefore, through this study, the influences of the façade and room configurations, together with the environmental factor on buoyant-driven natural ventilation, are addressed. An experimentally validated numerical model has been adopted to analyse the airflow characteristics inside the NVDSF and the room caused by combined radiation and natural convection. Results reveal that the primary influence comes from the dimensions of NVDSF, followed by the size of window openings. For the analysed NVDSF, an optimal gap depth is found at 0.2 m, and an optimal vent height is around 0.2–0.3 m. More gap depths result in more counterflows at the top, while a taller vent unnecessarily weakens the heat transfer. Besides, influences from room/window configurations also cannot be overlooked. Windows on the sidewall are found to deliver better indoor airflow coverage, although it gives around 2.5% less ventilation rate. Compared to a ‘no room’ condition (i.e., all the openings of the NVDSF are directly connected with outdoor but not room), our models with room only achieved 85–93% of the airflow rate depending on window sizes. It highlights the importance of considering room and windows for an accurate and practical assessment. Although the window locations and room dimensions draw minor impacts on the ventilation rates, the changes in airflow distribution prove their own importance in terms of air quality assessment.

Optical Power Distributions for 4×4 MIMO Visible Light Communications in Indoor Environment

Visible Light Communication (VLC) has emerged as a powerful technique for wireless communication systems. Providing high data rate and increasing capacity are the major problems in VLC. Recent evidence suggests that Multiple Input Multiple Output (MIMO) technique can offers improved data rates and increased link range. This paper describes the design and implementation of visible light communication system in indoor environment exploring the benefits of MIMO. The specific objective of this research was to implement a 4×4 Multiple Input (LEDs) Multiple Output (photodetectors)-VLC communication system, where a 16 white power LEDs in four arrays are setting up at transmitter and four RX modules are setting up at receiver side without the need for additional power or bandwidth as well as analyze a mathematical model for a VLC- 4×4 MIMO with different modes such as the suitable angles to cover the entire room. The research designs practically an electronic circuit for the transmitter and receiver with inexpensive components. The power distribution of different propagation modes is calculated for Single Input Single Output (SISO) and MIMO channels in typical room dimensions. The results in this paper indicate that the power is distributed uniformly for entire room when implemented VLC-MIMO as compared to VLC-SISO. Furthermore, a 4×4 MIMO implementing VLC is compared in term of BER vs. SINR with SISO communication system for both Line of Sight (LOS) and Non Line of Sight (NLOS) propagation modes. Comparing the two results of LOS and NLOS, it can be seen that a 4×4 MIMO implementing VLC for LOS perform better than the same system with NLOS due to decreasing in the received power resulted from the multipath effect.