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A previously healthy 30-year-old man presented to the emergency department with a 3-day history of worsening right-sided swelling of floor of mouth with odynophagia. According to him, this was his first episode. There was no prior trauma, fever, toothache, foreign body ingestion or dental extraction. No associated neck swelling, shortness of breath or constitutional symptoms were found. On examination, patient was not septic looking, floor of mouth was raised on right side, erythematous with non-discharging punctum (figure 1). Bimanual palpation revealed hard …

All we know, that technology plays a vital role in every work environment. IT facilitates accelerates the process of working and increases the productivity in every place including universities and academic centers. Specially, the internet as a source of knowledge paved the way for academic staff in universities to communicate, research, browse for scientific papers, use digital library and it serves them as an information provider and connector to worldwide. In addition, providing computer labs and delivering IT training for students are prominent for an academic institution. Hence, existing of an IT center in academic campus is an essential requirement, that we cannot ignore it. Afghanistan as a third world countries need to complete its path of maturity for IT infrastructure, which is acceptable right now, and must be developed for the future. Currently, Afghanistan universities are poor in the viewpoint of IT infrastructure (Buildings) except few of them that have it, especially in major cities. Therefore, it’s a need for Afghanistan to establish basic and standard IT centers in coming years for all cities to meet the demands of time, students and staffs. So as a result, prior to construction we need to have a manual or at least a paper to start this mission. Hence, this article provided the basic and standard requirements, along with proposed a simple architectural layout and detailed accommodation for networking and duct system including raised floors and suspended ceiling for IT centers in the context of Afghanistan, hope this paper will be used as a guideline for engineering and construction of IT centers for the future and existing universities.

In order to optimize structural design and balance heat distribution of the raised floor heating system heated by a burning cave, an unsteady heat transfer process of the raised floor was analyzed and discussed. An unsteady heat transfer model of the raised floor heating system was established to solve the problem of inner natural convection by air coupled with radiation and conduction heat transfer between two floor surfaces by computational fluid dynamics (CFD). Moreover, heating intensity, structural size and position of the heat source (burning cave) impact on the heat transfer performance and heating effect were discussed, which can provide a theoretical basis for parameter matching and structure optimizing. The results indicate that the best position of burning cave is under the center ground of a rural house, where the reasonable heat intensity of the burning cave is about 200 W/m2. The calculated temperatures and velocities are in reasonable agreement with measurements on the model house, which can provide a basic data support for the engineering practice of raised floor heating system.

Commonly encountered thermal management challenges of today’s rapidly changing power density, raised-floor hot/cold aisle data centers include typically uncontrollable tile flow non-uniformity along the above-floor cold aisle. For example, the operational cooling provision intensity near the Computer Room Airflow Conditioner (CRAC) unit can be far less than that on the other side (far away from the CRAC unit). This undesired trend leads to an unbalanced aisle-level air cooling and subsequent inefficient power consumption. In this study, the CRAC turbofan blower flow boundary conditions were thoroughly investigated. Computational Fluid Dynamics (CFD) based simulations were employed to describe and evaluate the differently configured CRAC turbofan blower flow conditions (i.e., normal, angled, and sheared CRAC flow patterns) as well as their impacts upon the air cooling performance. This work indicates that the considered turbofan blower boundary condition, together with their underlying transportation mechanism within the plenum, might contribute an essential influence to the flow structure adjacent to the tile perforations. In particular, it was found that the sheared CRAC turbofan blower airflow pattern is capable of giving rise to favorable tile flow straightening manners. This finding further promotes an improvement of the consequently obtained aisle-level air cooling effectiveness and efficiencies, contributing to more advanced data center thermal management in the future.

Many tile modeling studies have been proposed in the past, among which the most popular were body-force based models. Body force-based models applied a momentum source to simulate the effect of exiting jet of a perforated tile. Such imaginary momentum source terms would also add pressure to the system which does not exist in reality. In a circuit analogy of the fluid flow system, the pressure loss of perforated tiles is the resistance of the system. The change of pressure loss in the system inevitably changes the flow rate distribution on perforated tiles. However, most of past studies neglected the raised floor plenum in their models. The flow rate of perforated tiles was prescribed as a boundary condition. Consequently, the pressure changes due to the imaginary momentum source did not affect the flow rate on tiles. The additional pressure added by the source term needs to be offset if the plenum is modeled. This paper presents an improved Computational Fluid Dynamics (CFD) model for perforated tile in a data center with raised floor plenum. In this paper, a pressure compensated body force model was proposed and examined for perforated tiles in a full-featured data center laboratory at operating conditions. The air flows predicted by the new model was compared with experimental measurement with good agreement. The model’s effectiveness in predicting tile air flow distribution in the data center is demonstrated and analyzed.

Data centers are widely recognized for demanding many energy resources. The greater the computational demand, the greater the use of resources operating together. Consequently, the greater the heat, the greater the need for cooling power, and the greater the energy consumption. In this context, this article aims to report an industrial experience of achieving energy efficiency in a data center through a new layout proposal, reuse of previously existing resources, and air conditioning. We used the primary resource to adopt a cold corridor confinement, the increase of the raised floor’s height, and a better direction of the cold airflow for the aspiration at the servers’ entrance. We reused the three legacy refrigeration machines from the old data center, and no new ones were purchased. In addition to 346 existing devices, 80 new pieces of equipment were added (between servers and network assets) as a load to be cooled. Even with the increase in the amount of equipment, the implementations contributed to energy efficiency compared to the old data center, still reducing approximately 41% of the temperature and, consequently, energy-saving.

The purpose of the management of air distribution systems is to solve the problems in the cooling of data centers through minimizing the hot air recirculation and cold air bypass. In this paper, experimental and numerical analyses are conducted for the AUT data center. The data center performance indices have been compared between experimental and numerical solutions. According to temperature contours at a height of 1 m from the raised floor, recirculation of hot air to the cold aisle enclosure has occurred. For enhancement, the thermal management of the data center, cold aisle enclosure with decreasing supply airflow temperature to 18 , and hot aisle enclosure with return hot air from plenum ceiling to CRAC units were investigated. With the decrease in the total airflow supplied by CRAC units in the cold aisle enclosure and hot aisle enclosure models, the problem of Super-micro servers that experience about 50% more airflow than defined airflow for them in the base model, has been solved. The load on the cooling systems decreased from 13.2 kW up to 7.8 kW in hot aisle containment, the result is a hot aisle is a more suitable and appropriate configuration for the data center

Electromagnetic conducted noise that propagates through metallic cables often causes communication problems, such as interruptions in communication systems. When such a problem occurs, the frequency and strength of the conducted noise are investigated in order to determine the source of the conducted noise. We herein propose a method by which to measure the voltage to the ground of electromagnetic noise on metallic cables using shoe-shaped wearable devices to make the investigation easier. In the proposed method, maintenance personnel will stand on the devices and hold the signal cable to be investigated. The capacitive coupling between the feet and the floor is measured by the device, and the voltage reading of the measurement apparatus is adjusted using the capacitance in the measurement loop. The measurement accuracy and influence of the posture of the maintenance person are evaluated in a typical office with a raised floor with metal panels that form the return path of the conducted noise. In the present study, the measurement error was generally less than 3.85 dB, which is the expanded uncertainty allowed for measurement using a capacitive voltage probe, and the variation caused by the posture of the maintenance person was less than 2.6 dB.

The 33 full-factorial design is used in this study to investigate the effects of design parameters on the temperature distribution in a typical raised-floor data center quantitatively. Besides, the interaction effects of those parameters are researched. The design parameters include the computer room air-conditioning (CRAC) units layout, the cold aisle mode and the cold aisle width. In order to show the influence of different factors on the temperature distribution more intuitively, the heat mixing index (HMI) is utilized to characterize the temperature distribution in the rack. All operation models are conducted with a three-dimensional, non-isothermal steady-state computational fluid dynamic (CFD). The CFD software contributes to the qualitative study of the effects of design parameters. Results show that the CRAC units layout has the most significant effect on the temperature distribution. The second is the cold aisle mode, while the cold aisle width plays only a minor role. And the effect of the interaction between cold aisle mode and cold aisle width is estimated as being significant.

Energy efficiency is one of the most important issues in the design and operation of data centers. Energy efficiency implies efficient and environmentally friendly use of energy, namely heat recovery, flexible cooling management, use of terrain climate to beneData centers should not have transit communications (heating, water, sewer). However, for rooms containing servers, there are requirements for the level of humidity, so the presence of water is necessary at all times. The risk of flooding can be reduced by waterproofing. Y Servers require constant, round-the-clock cooling and heat removal, even if the data center is located on a pole. Therefore, the room must be equipped with an artificial climate system. Temperature and humidity must be monitored. Cabinets and racks should be arranged in an alternating pattern, so that the front side of the cabinets/racks in each row faces the front side of the other row, creating “hot” and “cold” passages. Cold air comes from under the raised floor, hot air goes to the ceiling: this is how air circulation occurs.fit infrastructure, carbon reduction, solar panels, etc.

Building Industries contributes to a great number of carbon footprint through all these years. Through a proper planning, this industry can reduce the impacts to the earth generally and towards the environment specifically. This study was dedicated to propose an old traditional design found in 400 years building to be reapplied in modern construction as a “passive design” system. Raised timber flooring was commonly applied in South East Asia’s traditional buildings due to the availability of the material and suitability for the climate. Masjid Kampung Laut was chosen as the case study due to its excellent reputation compared to the age period of the building. Till this moment, Masjid Kampung Laut is still function very well and benefit excellently to the community where it was located; Nilam Puri, Kelantan. This study was conducted in qualitative method, involving several types of data collection. The intention of this research whereby proposing towards the architects, designers, developers, engineers, and all the main players in the construction industry to reuse the design element of “raised floor” in modern buildings such as residentials, resorts and hospitality, mosques, retails, transit shelters and terminals, restaurants, schools, office buildings and etc. This revolution in design will at the end push the authorities to consider the design to be used in government buildings, as it also represent our architectural identity, energy sustainable, as well benefits the environment. In conclusion, the traditional architecture element of raised timber flooring could be redesigned and recommercialised to suit the future buildings. This design should be given a chance as it surely can benefit the building itself, the users, and the environment globally.

A data center cooling system consists of a hierarchy of systems with dedicated control algorithms dictating their operational states. There exists a wide range in spatial and temporal parameter space in an ensemble of non-linear dynamic systems, each executing a control task, while the global objective is to drive the overall system to an optimum operating condition i.e. minimum total operational power at desired rack inlet temperatures. Certainly, it is beneficial in optimizing workload migration at temporal scales but, solving the instability of the cooling systems operating at design points helps in understanding the whole system and make predictions to have better control strategies. Several techniques are available to realistically capture and make predictions. Datadriven modelling/Machine learning is one such method that is less expensive in terms of cost and time compared to other methods like validated CFD simulation/experimental setup.The objective of this study is to develop a control framework based on predictions made using machine learning techniques such as Artificial Neural Network (ANN) to operate multiple Computer Room Air Conditioning Units (CRAC) or simply Air-Cooling Units (ACU) in a hot-aisle contained raised floor datacenter. This paper focuses on the methodology of gathering training datasets from numerous CFD simulations (Scenarios) to train the ANN model and make predictions with minimal error.Each rack has a percentage of influence (zones) based on the placement of ACUs and their airflow behavior. These zones are mapped using steady state CFD simulation considering maximum CPU utilization and cooling provisioning. Using this map, ITE racks are targeted and given varying workload to force the corresponding ACU that is responsible for provisioning, to operate at set points. Number of such scenarios are simulated using the same CFD model with fixed bounds and constraints. Using large samples of data collected from CFD results, the ANN is trained to predict values that correspond to the activation of the desired ACU. Such efficient control network would minimize excessive cooling. The validated prediction points are used to model a control framework for the cooling system to quickly reach the operating point. These models can be used in real-time data centers provided; the training data is based on in-house sensor values.

With the explosion in digital traffic, the number of data centers as well as demands on each data center, continue to increase. Concomitantly, the cost (and environmental impact) of energy expended in the thermal management of these data centers is of concern to operators in particular, and society in general. In the absence of physics-based control algorithms, computer room air conditioning (CRAC) units are typically operated through conservatively predetermined set points, resulting in suboptimal energy consumption. For a more optimal control algorithm, predictive capabilities are needed. In this paper, we develop a data-informed, experimentally validated and computationally inexpensive system level predictive tool that can forecast data center behavior for a broad range of operating conditions. We have tested this model on experiments as well as on (experimentally) validated transient computational fluid dynamics (CFD) simulations for two different data center design configurations. The validated model can accurately forecast temperatures and air flows in a data center (including the rack air temperatures) for 10–15 min into the future. Once integrated with control aspects, we expect that this model can form an important building block in a future intelligent, increasingly automated data center environment management systems.

Modern data center facilities administrators are finding it increasingly difficult to lower the costs incurred in mechanical cooling of their IT equipment. This is especially true for high computing applications like Artificial Intelligence, Bitcoin Mining, Deep Learning, etc. Airside Economization/free air cooling reduces the mechanical cooling costs by using outside air to cool IT equipment under favorable ambient conditions. In this process, administrators risk their equipment to the exposure of fine particulate/ gaseous contaminants that might enter the data center facility with the cooling airflow. Literature suggests that the nature of failures caused by particulate contamination is very intermittent which makes the failures tough to predict. While the recommended filters can remove PM 10-2.5 , it's the fine and ultra-fine particulates like DPM (Diesel Particulate Matter), corrosive salts of high ionic content like sulfates and nitrates with low DRH (Deliquescent Relative Humidity) values that are the cause of concern. The present investigation utilizes a 3 - D CFD modeling of particle-laden flow in a rectangular flow domain, imitating the flow through floor tiles as in a raised floor data center. Literature was reviewed to study various numerical models that have been used for simulating particle dispersion and particle deposition in ventilated rooms, air ducts and particle behavior across physical obstructions of various geometries. A Discrete Phase Modeling approach was chosen using ANSYS FLUENT to calculate trajectories of the dispersed contaminants. 6SigmaRoom was used to predict accurate boundary and flow conditions of the fluid flow leaving the floor tiles.

As the world is moving toward edge computing, the need for small scale, widely distributed data centers became more critical. The traditional raised floor cooling techniques might not be applicable in these data centers and it could be more efficient to use in-row coolers. Recently, a small-scale data center was built at Binghamton University. This data center consists of ten cabinets and six in-row air cooling units combined into a single cold aisle enclosure. In this study, a CFD model for this data center is built considering all components using Future Facilities CFD tool (6SigmaRoom). After that, this model is utilized to conduct a detailed computational heat transfer analysis. These analyses include: the data center heat load, IT-equipment different configurations, in-row coolers supply air temperature, in-row coolers airflow rate, the data center running cost and some instructions to improve the data center performance. Moreover, behaviors that could harm the IT-equipment were identified and proposed solutions to ensure the IT -equipment reliability were presented. Results showed that the data center heat load should be limited to 156 kW (15.6 kW per cabinet) and the supply air temperature should not exceed 23°C. In case of installing switches, cabinet load should be limited to 14 kW.

To keep pace with the growing energy demand, legacy air-cooled data centers begun implementing energy efficiency strategies: Perfecting air flow management, enhancing cooling air delivery and collecting (re-using) waste heat. However, one may wonder: What is the magnitude of these energy savings? Is it worth the effort? The second law of Thermodynamics offers unique insights about energy wasteful practices by estimating the Exergy Destruction in a system. Exergy is equivalent to the “available energy”, hence the presence of inefficiencies “Destroys Exergy”. In this work, we numerically modeled the behavior of the airside in an existing data center laboratory (CEETHERM) using the commercial Finite Volume software 6SigmaDCXTM. The collected numerical data were used to post-process two Exergy Destruction approaches (Direct and Indirect method), whose behavior was tested against: (1) A simplified study case and (2) Actual data center flow. Both approaches worked well against the study case, although for case (2) the Indirect Method–which neglects turbulence effects–predicted zones of artificial negative Exergy Destruction. The Direct Method permitted associating large inefficiencies in the airflow to hot–cold airstream pre-mixing and important pressure drops in the raised floor. The airside Exergy Destruction encompassed a significant amount of the total irreversibilities in the system, suggesting that mitigating (or eliminating) it, can substantially improve energy saving efforts, especially in legacy data centers.

Airflow management in the data center is one of the most researched topics to achieve uniform airflow for effective thermal management. Recently, the Fan Wall Cooling (FWC) system is popular in air-cooled data centers due to the advantage of no raised floor plenum. In this research, a validated CFD model is used to study the FWC performance with different configurations to gain insights for the optimum design. Five new configurations are proposed to optimize the FWC performance along with ordinary FWC. Each of them has a different rack-tilted and row-tilted angle. The results show that tilting the rack by 15° towards the supply air direction can increase the rack air flowrate by 2.5% (800 CFM), and reduce the maximum normalized server temperature ( T s e r , m a x ∗ ) by 7% from 1.30 to 1.21. The CFD simulations also reveal that all new configurations can effectively mitigate the airflow maldistribution. Lastly, the FWC exhibits superior thermal performance compared to the conventional Underfloor Air Delivery (UFAD) and the Overhead Air Supply (OHAS) methods.

Recently, the rapid growth in both data center power density and scale poses great challenges to the cooling system. On one hand, the data center operators try to over provision cooling resources for fear of server failures induced by accumulated heat. On the other hand, they also want to reduce the energy cost as the cooling system takes up a significant portion of overall energy consumption. Among all available cooling solutions, air cooling dominates the data center industry due to its simpleness. However, its cooling efficiency has been questioned due to the low air density and specific heat. In this paper, we provide an overview for current endeavors to improve the air cooling efficiency. We group existing researches according to the locations where they can be applied from the perspective of air flow cycle. We also discuss the thermal measurement issues. We hope this paper can help researchers and engineers to design and control their data center air cooling systems.

Data centers are large facilities housing numerous IT equipment and supporting infrastructure. Frequent variations in IT load, continuous removal/addition/replacement of IT equipment for business requirement, cooling equipment, air supply settings, design layout, etc. make Data centers dynamic. Such complexities lead to overcooling and increased energy consumption. To reduce the energy consumption of the data center, a real-time control framework based on various thermal parameters inside the data center is imperative. Accurate prediction of various variables affecting the thermal behavior of the data center, especially for the small-time horizon, using computational fluid dynamics (CFD) simulations requires a large number of computational resources and physical time, making them unfeasible for real-time control of the data centers. Data-driven modeling especially, the Artificial Neural Networks (ANN) can be potentially helpful in such cases. This study aims to examine the ANN-based model with Multi-Layer Perceptron (MLP) to predict thermal variables such as rack air temperature inside data centers. The ANN-based models for the rack and facility-level system were trained and validated on the experiments and validated CFD data. The optimum delay for each case was found using cross-correlation between the input and output parameters of the ANN. The response of the multi-input multi-output ANN model was validated using R-value and mean square error (MSE). R-value for all the cases was approximately 0.99. This study recommends the use of ANN models for fast and accurate prediction of thermal parameters for real-time energy-efficient control of the data center system.

Perforated tiles are widely used in raised-floor data centers. The cooling air across the perforated tiles must be distributed properly to adequately cool the equipment. This paper aims at investigating the dependence of the pressure loss coefficient across perforated tiles with respect to the geometrical factors and flow parameters. Numerical simulations of flow distribution of perforated tiles were performed for different pore-type and flow parameters. The pressure loss coefficient upon the Reynolds number, the tile area, the porosity, the diameter of the hole, the thickness of the hole and the arrangement is studied. The fitting equation was provided to calculate the pressure loss coefficient. And experimental tests were taken to verify the validity of the model, comparison with the other empirical equations is provided. Based on the comparison, the fitting equation is more applicable to study the pressure loss coefficient for perforated tiles in data center.

This paper deals with the prediction of airflow and temperature distributions in data centers with the goal of achieving proper cooling of the computer equipment. The focus is on raised-floor data centers, but the material is equally applicable to other designs. First, the concept of a raised-floor data center is introduced and the cooling challenge is described. In this arrangement, cooling air is supplied through perforated tiles. The flow rates of the cooling air must meet the cooling requirements of the computer racks placed next to the tiles. These airflow rates are governed primarily by the pressure distribution under the raised floor. Thus, the key to modifying the flow rates is to influence the flow field in the under-floor plenum. Computational Fluid Dynamics (CFD) studies are presented to provide insight into various factors affecting the airflow distribution and the corresponding cooling and to explore various methods for controlling the airflow distribution. Then attention is turned to the above-floor space, where the focus is on preventing the hot air from entering the inlets of computer servers. Different strategies for achieving this prevention are considered. CFD modeling is ideal for understanding the behavior of these strategies and for determining their effectiveness. Some recent studies in these areas are summarized.

Data center thermal management is one of the focused research areas worldwide to optimize system performance to reduce electric power consumption [1]. One of the ways is effective airflow management by aisle containment. To achieve this, in this study we proposed vortex hot aisle containment first time in data center research community. The rack arrangement is designed in such a way that the hot aisle airflow can create the vortex due to pressure gradients. To characterize this airflow, we performed initial CFD simulations [2] and started the experimentation. This paper focuses on the experimental details of this study. Four 32U racks with 6U server simulators were tested in raised floor plenum data center facility at School of Commuting in the National University of Singapore. Initial steady-state experiments were performed for vortex hot aisle containment to monitor the rack inlet and outlet air temperature for varying heat load and server fan speed. Results show the favorable pressure variations to generate the vortex airflow inside the vortex hot ails containment and expect to give more insights with some more experiments.

Silo, in Brighton, was conceived in 2014 as a direct response to the huge amount of waste involved in the production and consumption of food around the world. Founder Douglas McMaster looks for alternative sources of nutritious foodstuffs from varied local and regional sources. Silo doesn’t accept plastic or non-biodegradable packaging from its suppliers, and reduces road, sea and air miles associated with the transporting of food by growing as much as it can on site. Tables are made from galvanised steel ‘tiles’, formerly a raised floor in a commercial office space. There is a bit of reprocessing involved in the manufacture of Silo’s plates: they are formed from old plastic bags and surprisingly look great and function perfectly. Described by McMaster as supporting ‘a pre-industrial food system’, Silo aspires to reacquaint us with sources of foodstuff that have been neglected for centuries or longer.

Optimizing data centers for energy efficiency plays a key role in the successful operation of modern data centers. One important factor is the proper management of airflow. In most air-cooled data centers, the required airflow for cooling of IT equipment is supplied from a raised floor to server racks through perforated tiles. In recent years, different approaches have been implemented to increase the efficiency of air delivery through tiles such as the use of directional tiles, adding understructure scoops or using air dampers [1]. Because the IT load of each rack in the data center is constantly changing due to the processing demands of the IT hardware at a given time, simultaneous manual tuning of the airflow at the panel level is impossible or at least impractical. The amount of airflow delivered to the Cold Aisle Containment (CAC) can be adjusted using Variable Airflow Panels (Dampers) that can be controlled remotely. In this study, a fuzzy control system is designed and optimized to control the open area ratio of air dampers in order to adjust the local airflow rate in the ES2 data center.

World over, power consumption by “server farms” or data centers is a growing concern. With time dependent job arrival rates at the servers, the power dissipation, and concomitantly the cooling requirements are dynamic. However, due to the lack of more efficient control algorithms, cooling systems are set to conservatively pre-determined set points, which result in sub-optimal energy consumption. An important step in the development of smarter control algorithms is detailed knowledge about the dynamic behavior of the data center system, which is missing in the open literature. In this paper, we have conducted transient experiments and CFD modeling to understand data center behavior for a broad range of time-varying input parameters such as CPU utilization, cooling air temperature and flow rates. Experiments at the server, rack, and facility level of raised floor plenum data centers were designed to record system responses to these input variable perturbations. The output responses were rack inlet-outlet air temperatures & CPU temperatures. A transient CFD model was validated with experiments. We foresee that these experimental results and the validated CFD model can be used in designing smarter control algorithms as a next step., by Yogesh Fulpagare, Atul Bhargav and Yogendra Joshi

Airflow is crucial for air-cooled data centers. Its flow path and distribution influences the thermal environment and energy efficiency of raised-floor data centers. This paper provides a review of the topic including the aspects of airflow factors, numerical study, airflow performance metrics, and thermal optimization. Based on the multi-scale characteristics of the data center, the thermal environment is categorized into room-level, rack-level, and server-level environments. For the room-level thermal environment, the main factors include layout, raised floor plenum and ceiling height, and perforated tiles. For the rack level, the effects of the porosity ratio of rack door, airflow rate/temperature, server population, server arrangement and power density are considered. For the server level, airflow rate and server fan speed are investigated. Moreover, numerical studies have been widely employed to understand the thermal environment of data centers. The selections of simulation tool and the methods for simplifying and validating the models are key to predicting the data center's thermal behavior correctly. In addition, airflow performance metrics and multi-scale thermal optimization are summarized and discussed. This review aims to emphasize the importance of the airflow in data centers and thus serve a guiding reference for airflow design and energy efficiency in data centers. Some recommended topics for future research are also provided.

This paper investigates a novel terminal unit that integrates a radiant cooling floor (RCF) with an underfloor air distribution system (UFAD). The unit consists of rectangular modules that are installed above the standard structural floor of the building, creating a raised floor. The upper face of these modules incorporates a grid for easy installation of the pipes of the RCF, while the space between the raised floor and the structural slab is used as the air supply plenum of the UFAD system. The proposed system presents some advantages over the standard air systems: (1) it allows increasing production and zone set point temperatures, which improve the efficiency of the chiller plant, (2) improved comfort, and (3) improved air quality due to reduced mixing within the occupied zone. The proposed system can also solve or mitigate some of the drawbacks of cooling floors: (1) prevent water condensation over the surface of the floor, (2) increase the cooling capacity of the floor, and (3) reduce the response time to changes in the space thermal loads. The interactions between the RCF and the UFAD are not evident. In this paper, the thermal behavior of the combined unit is investigated by means of a numerical model implemented in COMSOL Multiphysics. The accuracy of this model is checked against three experiments undertaken in laboratory using a scale model of the system. In the first experiment, the air above the floor is kept quiescent and the cooling capacity is measured. The maximum relative error between the predicted and measured capacities is 19.5%. The numerical model is then used to study how the air movement within the plenum modifies the transient thermal response of the unit. The second and third experiments are designed to quantify the temperature change of the air circulating within the plenum (thermal decay or TD). In nominal operating conditions, TD is about 2.7 °C. In short, the new terminal unit is like a radiant cooling floor and a UFAD system working separately, but integrated in the same terminal unit.

Natural and environmental conditions were the main factor that caused people make adjustments to their residences. People need houses with the reasons are usually to meet the needs of privacy, comfort, storage of possessions, acquisition, storage and preparation of food, shelter from the weather protection from insects and/or pests, safety, kinship and social, gathering and travel, and movement. The condition of balance is achieved by the design adjustments made so that the buildings cause the least amount of impact on the surrounding environment. The advantages of the stage house for a hot and humid climate area of West Kalimantan is done to responds the ecological advantages of surrounding environment. The raised floor feature has been the best mitigation feature not only to keep dry from constant flood but also to built into the nature whilst living near riverside area. The stage house with modern concept can be designed to allow for cross ventilation, natural lighting, thermal comfort, privacy (visual and social), functionality and the effective cost for house handling.

Raised floors with hot-aisle/cold-aisle configurations have grown to be a critical arrangement for data center cooling. However, more sophisticated techniques are still desired to achieve proper thermal management for improving energy effectiveness and efficiency. The application of fan-assisted perforations may yield a smarter cooling solution accommodating non-uniform power densities and heat load demands to optimize the cooling performance in raised-floor data centers. The present research includes the construction and thermal analysis of a basic raised floor with compact fan assisted perforations modeled using computational fluid dynamics (CFD). The flow straightening effect of the fan-assisted tile and the fan-to-tile distance were treated as the critical design aspects under investigation. The field cooling performance affected by the parametric variation were carefully discussed and compared. Moreover, a full factorial design was employed to obtain and verify the qualitative and quantitative characteristics of the main and interaction effects of the design variation. Well-constructed fan-assisted perforations may satisfy an advanced cooling solution to better manage and optimize the heat and mass transfer in data centers.

The widespread use of data centers, the dramatical increase of the data center power density and the need for improving cooling system efficiency to maintain reliable operation temperature and save cooling energy make the study of data center thermal management an urgent issue. In the current paper, three different configurations for thermal management solution of high power density data centers are investigated, compared and evaluated. A scaled physical model data center has been designed and constructed for the sake of the study using the theory of scale modeling of air flow experiments. The results showed that (i) by using aisle partition and aisle containment the rack inlet temperature can be reduced by 3–13% and 13–15.5% for aisle partition and aisle containment configurations, respectively; (ii) the intake air temperature reduction increases with increasing power density; and (iii) using aisle partitions and aisle containment with raised floor improves the data center cooling performance.

The COVID-19 pandemic has shown that the current ventilation design, especially in residential buildings, may not provide healthy air exchange. Since current buildings in tropical climate only focused on cooling, its have become sites of rapid COVID-19 transmission. In order to avoid indoor SARS-Cov-2 transmission, some studies recommended an increase in air supply with a higher air exchange rate and to reduce the usage of the air conditioner. Flores has been designated one of the top Indonesian tourism destinations. However, access to transportation is still tricky. Analysis of local materials, culture, and weather can reduce the building cost and preserved local value to become the area's identity. Vernacular housing in Indonesia has adapted well to climatic conditions in different locations by using natural ventilation that ensures thermal comfort. We propose a ventilation design with natural ventilation from Mbaru Niang's traditional house. It was found that raised floor, verandah, and sun shading can reduce the hot temperature from solar radiation and hot wind from the sea breeze. This modern building concept can become a practical, healthy, and environmentally friendly solution for building in Flores, Indonesia. Introduction

The growing number, size, complexity, and energy density of data centers result in considerable energy challenge. The implementation of efficient and eco-friendly cooling systems, strategies, and methods that can help reduce the energy consumption of traditional cooling systems is imperative for data centers. In this study, an innovative concept of a solar chimney-based direct airside free cooling (SC-DAFC) system is proposed for data centers to achieve energy saving. A theoretical model of the SC-DAFC system is developed to evaluate the indoor thermal environment, ventilation flow rate, and heat recovery of the data center under given climate conditions. 3D numerical simulations are carried out to investigate the effects of raised floor height and turbine pressure drop on the cooling performance of the system. An economic analysis is also conducted by calculating the net present value and dynamic investment recovery period of the project. Results indicate that the thermal environment in the SC-DAFC data center can meet the cooling requirements under favorable climate conditions, and such project has strong profitability. The SC-DAFC system is technically and financially feasible, thereby providing efficient solutions that reduce energy consumption and operational costs.

Data centers are energy-intensive facilities, and their thermal environment and energy efficiency are key research areas. In this study, the airflow distribution and energy consumption of a campus data room were experimentally investigated, and the results pertaining to raised-floor (before retrofitting) and row-based (after retrofitting) cooling were compared. The thermal environment was evaluated in terms of the rack cooling index (RCI), return temperature index (RTI) and supply heat index (SHI), and the energy efficiency was estimated using the power usage effectiveness (PUE) and mechanical load component (MLC). The results indicated that row-based cooling corresponded to a better thermal environment and higher energy efficiency compared with those of raised-floor cooling. The SHI decreased from 0.79 to 0.31, and the difference in the PUE and MLC values before and after retrofitting was 0.27 and 0.14, respectively. These benefits can translate into a total energy saving of 110,829 kWh per year. However, row-based cooling involves certain limitations, such as the presence of vortexing airflow, uneven air supply temperature, and interaction among different modules, which must be further examined. This paper proposes an index that can be used to evaluate the interaction among different modules.

This study presents the flow of cooling air in a single rack data centre test bench with 40 servers with cold/hot aisle containment and a raised floor with a floor tile. The inhomogeneous pressure and velocity field in the cold aisle and the effect on the local server fan power were assessed. Computational fluid dynamic simulations as well as measurements were performed. Due to the cold/hot aisle containment, the floor jet caused a low pressure region for the lowest rack positions 1–10. In the simulation this led to a predicted increase in server fan power consumption of up to 6% for the lower rack positions. In the experiments, an increase of the server fan power for lower rack positions was likewise noticeable but was blurred due to the variance between individual servers. The influence of the vertical pressure distribution on the total server fan power consumption was minor (below 2%) if leakage is neglected. Six partially covered floor tile configurations were investigated. Partially blocking the floor tile to redistribute the flow showed no beneficial effect in homogenising the vertical pressure distribution because of the resulting increase in floor jet velocity. The simulations over-predicted the vertical pressure inhomogeneity in the contained cold aisle because leakage was not taken into account.

This paper aims to introduce a quantitative method to builders for the most appropriate material selections based on multiple attributes and integrate decision group member opinions throughout bidding process. In this respect, a new model used together with the Analytic Hierarchy Process (AHP) and fuzzy Multi-Objective Optimization on the Basis of Ratio Analysis (MOORA), multi-criteria decision methods are proposed. In a real decision process, there are many uncertainties and ambiguities. In fact decision makers cannot always provide practical guidelines and especially precise judgments due to time limitations. The intelligent model proposed demonstrates that the AHP and fuzzy MOORA approach can not only be used easily to imitate the decision duration in the material selection but also the results obtained from this work provide contractors valuable insight into the material selection problem. At the same time, the quantitative analysis method based on the appropriately raised floor materials along the bidding process enables the builders to use their restricted resources more expeditiously and enhances considerably the possibility of winning agreement, as one of the most striking points deduced from the present study. In short, the model with AHP and fuzzy MOORA approaches can assist the builders to improve resolutions for the bidding. © 2018 The Author(s). Published by VGTU.

In this paper hard floor and raised floor cooling of servers are numerically compared. Both time-averaged and transient distributions of velocity and temperature fields are investigated with the use of computational fluid dynamics. The geometry and boundary conditions are based on Module 2 of the RISE SICS North facility located in Lulea, Sweden. Results show that for hard floor configurations, it is important to ensure that the hot air does not enter the server inlets on the return to the cooler unit. For raised floor configurations, the interplay between inlet air velocity and server fan speed should instead be considered. Flow fields further indicate that flow direction control of the outlet air in hard floor configurations and inlet air in raised floor configurations can be applied to improve the energy efficiency of the server room. Regarding transient effects, the hard floor configuration show overall larger velocity oscillations while corresponding temperature variations are comparatively small.

Underfloor air distribution (UFAD) systems use the underfloor plenum beneath a raised floor to provide conditioned air through floor-mounted diffusers, which typically discharge cool air with both horizontal and vertical momentum components. These systems usually create a vertical temperature stratification when in cooling mode and this has an impact on energy, indoor air quality and thermal comfort. The purpose of this study was to characterize the stratification performance of a previously unstudied type of floor diffuser that discharges air horizontally, with almost no vertical velocity component, and that aims to combine the benefits of both UFAD and displacement ventilation (DV) strategies. We performed 19 full scale laboratory experiments in which we varied the number of diffusers and the internal loads over a range of values typically found in office spaces. We quantified the amount of thermal stratification by measuring the dimensionless temperature at ankle height and found a degree of stratification that is typical of DV systems – higher than is typical in UFAD systems. We developed a model based on these results that can be used to simulate these systems in whole building energy simulation tools, such as EnergyPlus, and simplified UFAD design tools.