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Nowadays Best Estimate Plus Uncertainty (bepu) methods are applied in nuclear safety investigations with thermal-hydraulics system codes. Their applications remain challenging because (1) many semi-empirical parameterized models are relevant in a given accidental scenario, (2) model parameters probability density functions are often only determined by expert judgement, and (3) models exhibit discrepancies. Inverse uncertainty quantification methods, such as Bayesian calibration, have recently been used to inform model parameter probability density functions based on Separate Effect Test Facility (setf) experimental data. In this paper we present the application of hierarchical Bayesian calibration to choked-flow experimental data from two setf s, provided in the context of the oecd/nea atrium project. This calibration can accommodate boundary conditions varying from one setf to another and account for code inadequacies by inflating the model parameter uncertainties. As such and contrary to standard Bayesian calibration, the method yields a unique joint posterior probability density function validated on similar experiments and applicable for forward uncertainty quantification of an accidental scenario. • PDFs of TRACE choked-flow parameters derived with Bayesian calibrations (BC) • BC performed using standard and hierarchical methods • BC calibration was performed with data from several SETFs • Standard BC posterior PDFs cannot capture data from all SETFs • Hierarchical BC captures well the variability between data of different SETFs • Hierarchical BC yields validated posterior PDFs [ABSTRACT FROM AUTHOR]

Abstract Traditional observation analysis techniques are widely used by researchers to analyze public spaces, in terms of visibility, and movement patterns. This method enables the researcher to have realistic results, however it depends mainly on the researcher's views. The main aim of the research is to reach a more reliable method for evaluating and analyzing connectivity by integrating traditional observation techniques with a more accurate analysis technique, like Depthmap software analysis. The study highlights the importance of applying this technique along with observation method to assist and validate the results. The research was conducted by applying the two analysis techniques on two atria, inside "City Stars Mall" shopping center, located in Cairo city. Both atria are similar, however, the first atrium has a larger scale, while the second has a smaller scale. Results show that Depthmap analysis technique is better in smaller scaled atrium spaces, while observation is more realistic in larger scaled spaces. Each technique has its advantages over the other. However, the paper proves that in order to reach a clear and accurate analysis, both techniques must be applied together for accurate and reliable results. [ABSTRACT FROM AUTHOR]

Highlights • CFD simulations were carried out to investigate the smoke management in a mall. • The smoke layer height, smoke mean temperature, and mean soot density were studied. • The material of the fire source is wood with total heat release rate 3.65 MW. • Fifteen simulations were carried out and an optimum scenario was reached. Abstract This paper shows a numerical investigation on smoke management techniques inside a large building. Fifteen numerical simulations were carried out using fire dynamic simulator FDS software. The effect of adding a mechanical exhaust louver on the roof inside the building is studied. This was carried out by varying the exhaust ACH and the configuration of the exhaust openings. Also, the effect of injecting fresh air into the building was examined by investigating the effect of changing the make-up air ACH and the location of the make-up air. All cases were analyzed by studying the smoke layer height, mean soot density and the mean temperature of smoke. It was observed that the smoke hazard decreases by increasing ACH, using multiple exhaust points, and adding make-up air. As compared to no smoke management, this enhancement reaches 71.18% for the smoke layer, 31.6% lowering the average temperature, and 38.4% decreasing the average soot density. These results were achieved when six opposed supply louvers and one exhaust louver were used for the smoke management system. [ABSTRACT FROM AUTHOR]

Abstract: Building integration of photovoltaics (PV) has long been acknowledged as a key application for PV in developed countries. The avoided use of comparably priced alternatives such as polished or cut stone in commercial facades enables PV to be applied often at little or no additional cost. The use of semi-transparent PV modules within commercial atria represents an interesting application in this respect as they can be used to replace traditional shading solutions which often have a high maintenance burden. However, compared to standard double glazing, an element incorporating either mono or poly crystalline PV cells in a glass–glass construction comes at a cost premium. To justify such an application there must be significant added value in the PV solution. This paper critically appraises a semi-transparent PV atrium which links two administration buildings at the University of Southampton, enclosing the main campus reception desk. Choosing PV laminates for the atrium roof has multiple benefits for the building users and the wider University, such as electricity generation, solar shading, environmental and technology statements, enhanced comfort and prestigious office workspace. This paper compares alternative shading solutions for the atrium and discusses user perception of the building and the atrium’s impact on their personal workspace. It is shown that PV in commercial atria does not always have to be considered as a ‘luxury’ option. With appropriate consideration of added value factors its selection can be justified in terms of both cost and carbon footprint. [Copyright &y& Elsevier]

This paper presents an analysis of the impact of selected design alternatives on the thermal and energy performance of atriums based on the methodology outlined in the accompanying paper. Computer simulation programs were used to predict the impact of the selected design alternatives on the design performance outputs of atriums. Design alternatives focused on fenestration glazing types, fenestration surface area, skylight shape, atrium type, and interaction of the atrium with its adjacent spaces. Design performance outputs, evaluated with respect to a basecase design, included seasonal solar heat gain ratio, cooling and heating peak load ratios and annual cooling, heating and total energy ratios. Design tools were developed to quantify the impact of the design alternatives on the performance outputs. The design tools were cast into two-dimensional linear relationships with the glazing U-value and SHGC ratios as independent parameters. The results for enclosed atriums showed that the annual cooling energy ratio increased at a rate of 1.196 per unit of SHGC ratio and decreased at a rate of 0.382 per unit of U-value ratio. However, the annual heating energy ratio increased at a rate of 1.954 per unit of U-value ratio and decreased at a rate of 1.081 per unit of SHGC ratio. Similar trends were also found for the three-sided and linear atriums. Pyramidal/pitched skylights increased the solar heat gain ratio by up to 25% in the heating season compared to flat skylights. The effect of the skylight shape on the annual cooling and heating energy may be positive or negative, depending on the glazing U-value and SHGC ratios and the atrium type. Atriums open to their adjacent spaces reduced the annual cooling energy ratio by up to 76% compared to closed atrium spaces. However, open atrium spaces increased the annual heating energy ratio by up to 19%. [Copyright &y& Elsevier]

This paper analyses annual energy performance of atrium type hotel building in Belgrade. The objective is to examine the impact of the atrium on the hotel building’s energy demands for space heating and cooling. Integrated approach through numerical simulations that include Belgrade climate data and thermal comfort parameters, indicates an optimal model of hotel building with atrium for this area. Building energy simulation is carried out using EnergyPlus simulation engine, as a basic tool in the process of building energy optimization. The methodological approach includes the creation of a hypothetical model of an atrium type hotel building, numerical simulation of energy performances of several design alternatives of the hotel building with atrium, and comparative analysis of the obtained results. The main task of analysis is to change certain parameters in the particular model (for example, building structure, orientation, etc.) and to observe how the changes influence energy performance of the building. The goal of this research is to show that the atrium contributes to the heating and cooling energy savings in the rest of the building, but also that the atrium itself demands a lot of energy for its air-conditioning. The most sustainable solution should be to cover energy demands for atrium by using the renewable energy sources. In this case, the atrium can contribute to the energy efficiency of the hotel building in Belgrade climatic conditions, thus reducing its negative impact on the environment. [ABSTRACT FROM AUTHOR]

In the present paper, a new daylight performance metric, Daylight Illuminance Ratio (DIR) has been developed for an atrium space to take into account the direct and diffuse components (Sun and sky). The daylight performance on each inner surface of a square atrium has been investigated and validated with hourly measured experimental data under clear sky conditions. There is good agreement between theoretical and experimental values, with a correlation coefficient (r) of 0.92–0.96 and a root mean square percentage error (e) of 8.53–10.21%. Results show that the interior surface of the west and north walls receive more daylight in June (summer) and October (winter), respectively. The presented metric can be used to predict vertical illuminance at a given point on the atrium walls. [ABSTRACT FROM AUTHOR]

This paper takes an atrium as the object of study, according to the design parameters of the space size and air conditioning, the model of stratified air conditioning is established. It used FLUENT to simulate the air flow structure and thermal comfort of the stratified air conditioning under the winter heating condition, and the results were analyzed. The results show that setting the radiant floor heating is beneficial to control the heat convection and the vertical temperature gradient can be effectively reduced. Therefore, the effect of winter stratified air conditioning can be achieved. From the view of comfort, the middle air supply is better than the two side air supply. [ABSTRACT FROM AUTHOR]

Cardiac auto-regulation involves integrated regulatory loops linking electrics and mechanics in the heart. Whereas mechanical activity is usually seen as ‘the endpoint’ of cardiac auto-regulation, it is important to appreciate that the heart would not function without feed-back from the mechanical environment to cardiac electrical (mechano-electric coupling, MEC) and mechanical (mechano-mechanical coupling, MMC) activity. MEC and MMC contribute to beat-by-beat adaption of cardiac output to physiological demand, and they are involved in various pathological settings, potentially aggravating cardiac dysfunction. Experimental and computational studies using rabbit as a model species have been integral to the development of our current understanding of MEC and MMC. In this paper we review this work, focusing on physiological and pathological implications for cardiac function. [ABSTRACT FROM AUTHOR]

One of the most lucrative renewable energy sources for supplying energy in future decades is the solar energy. Solar energy can be utilized through both active and inactive systems. Inactive solar systems are the ones which collect and store solar energy without the use of energy-consuming devises such as pumps or controllers, so that the energy can be used at the time of need. This causes the amount of energy consumption in different parts of a building to reach their point of minimum. There are different methods for the utilization of the solar energy in an inactive way, namely solar windows, solar greenhouse method, Trombe wall and aqua wall, atriums, and pools on the roof tops. In this paper, the most common methods of using solar energy in inactive ways, which are atriums, Trombe wall, and solar greenhouse are analyzed. The method of the research is descriptive-analytic so that with better knowledge, modern designs can gain full benefit from these techniques. [ABSTRACT FROM AUTHOR]

The paper is dedicated to the creation of the atriums in the historical centre of Saint-Petersburg for improving the quality of courtyards. Since 19 century Saint-Petersburg was built mostly with brick buildings along the perimeter of allotments with founding one or several courtyards. “Well-like” courtyards of historical buildings of Saint-Petersburg have typically a lack of illumination and insolation, are badly ventilated and are often transformed into parking lots for inhabitants. Possibility of glassing of “well-like” courtyards is analyzed from the viewpoint of historical buildings protection regulation of Saint-Petersburg and norms of insolation and illumination of the dwelling buildings, basing on the actual experience in the creation of atriums in Saint-Petersburg. [ABSTRACT FROM AUTHOR]

In a well day-lit space when the daylight intensity is far more than the required value, photoelectric switching can result an excellent energy saving. However, a problem with the switching control type is the frequent and rapid switching of lights on and off, particularly during the unstable sky conditions when daylight levels are fluctuating around the switching lighting level. This can annoy occupants and lessen lamp life. This paper studies the simple and a few variants of photoelectric switching controls namely standard, differential, switching time delay, daylight time delay and solar reset types which can affect the number of switching operations and the corresponding lighting energy use. For a given time delay, daylight linked time delay performed better than switching linked time delay in terms of the number of switching operations. Several mathematical expressions were established to predict the lighting energy savings at various atrium floors. The findings provide important information and insight into the effects of different switching controls in terms of energy savings and real-time operations. [ABSTRACT FROM AUTHOR]

Abstract: Despite significant impacts of natural ventilation on atria, indoor thermal conditions and decreasing energy usage load, there is lack of knowledge about how various design parameters influence atria thermal conditions. The complexity of natural ventilation design of atria and inadequate simulation design tools may lead to inaccurate atria thermal prediction. In the past 25 years, researchers have developed and suggested various methods such as experimental, theoretical and numerical modeling to identify thermal and ventilation performances of atria. However, the diversity of the modeling conditions makes it difficult to achieve proper conclusions which link all contributing parameters to atrium thermal conditions. This paper provides a comprehensive review of previous studies on the role of natural ventilation in atrium buildings in different climates, efficient design parameters and their application to improvement of thermal performance and decrease of energy consumption. These parameters include various atrium configurations and components such as atrium geometry, opening characteristics, roof properties, materials and fenestration characteristics. The review further highlights different ventilation techniques which can be applied in atria as assisted ventilation methods. The cited parameters can be categorized into those affecting thermal performance and ventilation performance. The outlet opening size is the most influential parameter that affects both indoor thermal condition and ventilation behaviors of atria and consequently decreases energy usage load. [Copyright &y& Elsevier]

Abstract: With increased global concerns on climate change, the need for innovative spaces which can provide thermal comfort and energy efficiency is also increasing. This paper analyses the effects of transitional spaces on energy performance and indoor thermal comfort of low-rise dwellings in the Netherlands, at present and projected in 2050. For this analysis the four climate scenarios for 2050 from the Royal Dutch Meteorological Institute (KNMI) were used. Including a courtyard within a Dutch terraced dwelling on the one hand showed an increase in annual heating energy demand but on the other hand a decrease in the number of summer discomfort hours. An atrium integrated into a Dutch terraced dwelling reduced the heating demand but increased the number of discomfort hours in summer. Analysing the monthly energy performance, comfort hours and the climate scenarios indicated that using an open courtyard May through October and an atrium, i.e. a covered courtyard, in the rest of the year establishes an optimum balance between energy use and summer comfort for the severest climate scenario. [Copyright &y& Elsevier]

Abstract: The performance efficiency of natural smoke ventilation in atria spaces are influenced greatly by several design decisions such as atrium shape, height, size and openings location. This paper investigates the impact of atrium shape (horizontal profile) on smoke ventilation performance in naturally ventilated atria. Three different configurations (square, rectangular and triangular prism) with the same area, height, and hence, volume were tested. The smoke ventilation performance is being assessed in terms of smoke filling time using a computational fire dynamic simulator (FDS). FDS is used to simulate the natural smoke filling resulting from atrium fire in the three configurations. The smoke layer interface height as a function of time and soot mass fraction and temperature as a function of height have been registered during the simulation. The predicted transport lag time for initial formation of the smoke layer beneath the ceiling (ceiling jet) was compared for the three tests. In order to test sensitivity of the shapes, all other parameters were designed to be similar in the three tests, and the same fire scenario was applied including inlet and outlet area, and fire size and location. The results showed that the rectangular configuration contributes better to smoke ventilation, and that the triangular configuration is the most critical in terms of smoke filling time, followed by the square configuration. [Copyright &y& Elsevier]

Abstract: In subtropical Hong Kong, a certain amount of electricity is used to create visually comfortable interior spaces through electric lighting, which is the second major electricity-consuming item in commercial buildings, accounting for 20–30% of total electricity use. The burning of fossil fuels for electricity generation has many adverse effects on the environment. Daylighting is an important and useful strategy for enhancing visual comfort and reducing the need for the electricity consumed by light fittings. The rational use of daylight through tools such as photoelectric lighting controls can effectively reduce buildings’ electricity consumption and the related pollutants and greenhouse gas emissions. Daylighting design techniques are often best demonstrated via field measurements that provide reliable operational and energy performance data for establishing design guidelines. An atrium provides an environmentally controlled indoor public space that introduces daylight into the hearts of large buildings. In circulation areas such as corridors, people expect the way ahead to be sufficiently lit and daylight-linked lighting controls can deliver excellent energy savings. This paper presents the daylighting and energy performance of an atrium space using daylight-linked lighting controls. The cost, energy and environmental issues related to various daylight illuminances are estimated and design implications are discussed. [Copyright &y& Elsevier]

Abstract: The hot smoke test is often used for commissioning fire smoke management system in atrium buildings, in which liquid fuel is burnt to generate a buoyant plume mixed with artificial tracer smoke to model a fire smoke. The method is usually costly and often causes safety concerns. This paper studied an alternative method of using a cold smoke test, in which pure helium is used to create the buoyant plume. A method was developed to determine the supply rate of pure helium necessary to achieve the same buoyancy effect as that of the corresponding hot smoke test. Computational fluid dynamics (CFD) simulations of the helium smoke tests were conducted and compared to the measured hot smoke tests in a full-scale naturally ventilated atrium and a sub-scale atrium with mechanical ventilation. A new method was added in the CFD model to track the smoke layer height for the simulations of helium smoke based on the concentrations of smoke and helium. It is found that the predicted smoke layer heights based on the mass fractions of the tracer smoke are generally close to the measured ones in the hot smoke tests of different heat release rates. A non-dimensional temperature in the hot smoke test is also found closely related to the dimensionless helium concentrations in the helium smoke test for the atria modeled. Although the consumption of pure helium for a full-scale helium smoke test can be very high, it is promising to use the pure helium smoke test in the lab-scale experiments as the preliminary tests of full-scale and/or lab-scale testing of real fires. [Copyright &y& Elsevier]

Abstract: It is a common practice to use reduced-scale experiments to develop formulae for the design of smoke and heat exhaust ventilation systems. Implicitly, up-scaling of results is assumed justified. A similar approach can be adopted with numerical simulations, i.e. a reduced-scale setup can be up-scaled to compare results to full-scale observations. However, both in numerical simulations and in experiments, scaling must be done in a proper way. The classical method for up-scaling results obtained in fire related experiments is based on preservation of the Froude number only. The present paper, focusing on the up-scaling of results by means of a series of CFD simulations of fire-induced flows in an atrium configuration, confirms this to be justified as long as the flows in both the reduced-scale and full-scale configurations are sufficiently turbulent. If this is not the case, it is illustrated that other dimensionless numbers must also be preserved in scaling, in addition to the Froude number. [Copyright &y& Elsevier]

Abstract: This paper analyzes and studies the applicability of video image, infrared and ultraviolet/infrared (UV/IR) flame detectors for high and large spaces, atrium in particular, and a test simulating the actual working conditions and typical interference from ambient light is designed based on the operation principles of flame detectors and their operation limits to offer important testing methods and data for the research on applications of flame detectors to large space locations and fire prevention design. [Copyright &y& Elsevier]

Abstract: The paper explores mixed-mode cooling strategies in buildings with hybrid ventilation and high levels of exposed thermal mass and presents data collected over an extensive period of time using a full-scale experimental set-up in an occupied institutional building with motorized façade openings integrated with an atrium. Night cooling strategies for thermal mass pre-cooling, with variable low temperature setpoint for control of airflow through operation of motorized grilles or a possible variable speed fan, are evaluated. Results for the thermal conditions in the highly-glazed atrium zone and the wind and buoyancy-driven airflow rates show that free cooling covers a significant portion of the building''s cooling requirements while maintaining a comfortable indoor environment. The heat removal from concrete floor slabs is 2–5 times higher with the inlet air stream at an average temperature of 12 °C, compared to that with an air stream at 15 °C or 18 °C respectively. These findings provide insights for space conditioning using hybrid ventilation that can support the development of model-predictive control strategies. [Copyright &y& Elsevier]

Abstract: The present paper is focused on the fluid dynamics of the make-up air at the vents in case of an atrium fire, its influence on the fire-induced conditions and the necessity of properly modelling it to obtain a reliable numerical prediction. For this aim, experimental data from two full-scale atrium fire tests conducted in a 20m cubic facility, with venting conditions involving mechanical smoke exhaust and make-up air velocities larger than 1m/s, and with different fire powers, are presented. Subsequent numerical simulations of these tests have been performed with the code Fire Dynamics Simulator v5.5.3. Two different approaches have been followed to simulate the make-up air inlet fluid dynamics, involving one domain which only considers the inside of the building and another which includes part of the outside. In the former simulations, anomalous phenomena around the fire appear, while the inclusion of part of the exterior domain results in completely different fluid dynamics inside the facility, which agrees better with the experimental data. A detailed analysis of the fluid mechanics at the air inlet vents is conducted to explain these discrepancies. Finally, further simulations are performed varying the make-up area and the exterior extension to assess the appearance of the aforementioned phenomenon. [Copyright &y& Elsevier]

Abstract: In this paper the performance of various turbulence models potentially suitable for the prediction of indoor air flow and temperature distributions in an atrium space was evaluated in a systematic way. The investigation tested these models for various thermal conditions in atria of different geometrical configuration in two existing buildings using the Reynolds Averaged Navier–Stokes (RANS) modeling approach. The RANS turbulence models that were tested include the one-equation model (the Spallart–Allamaras) and two-equation models (the standard k-ɛ, RNG k-ɛ, realizable k-ɛ, standard k-ω and SST k-ω models). The radiation exchange between the surfaces of the atrium space was considered using the Discrete Transfer Radiation Model (DTRM). The resultant steady state governing equations were solved using a commercial CFD solver FLUENT. The numerical results obtained for a particular time of the day were compared with the experimental data available. Relatively good agreement between the experimental and CFD predictions was obtained for each model. However, from the results obtained, it was found that the performance of two-equation turbulence models is better than one-equation model and among the two-equation models, the SST k-ω model showed relatively better prediction capability of the indoor environment in an atrium space than k-ɛ-models. [Copyright &y& Elsevier]

Abstract: Atrium of student union is a typical crowded place, it is difficult to achieve within the fire and smoke-protect separation. Once smoke entered, the security evacuation of personnel was threatened by rapidly spread smoke. In this paper, the atrium smoke exhaust design was researched, first introduces the method of smoke control in atrium buildings, research Smoke control system design theory with engineering examples, using FDS for atrium smoke control the numerical simulation, calculate a variety of exhaust design simulation results was calculated, enhanced the scientific and economy of smoke design through comparing. [Copyright &y& Elsevier]

Abstract: With the rapid economic development of our country, the speed of city construction is accelerated and more proposed development with super high and super large space construction has appeared, hence the relevant fire problems are still a challenge. It''s acknowledged that performance-based design provides more reasonable and innovative design strategies for fire engineers. The CFD simulations are always executed to validate the feasibility of performance - based design. Current fire safety engineering design and fire engineering researches are focused on the fire generating and smoke migrating in the building. Seldom consideration is given on how the natural wind of outside the building affects the smoke migration pattern. However, it will be unrealistic that ignore the natural wind factor in smoke control design. Especially, it will be unacceptable in the natural wind smoke control design which utilizes the natural wind to exhaust smoke out of the building. As well as more investigations will be required in the mechanical smoke control design. The paper integrates the PHOENICS which is the general purpose CFD software with the statistic data about the natural wind from the specific area/city to analyze how the natural wind can impact on the fire and smoke generated in the atrium of a large space building, so as to provide some references for the future smoke control designs. [Copyright &y& Elsevier]

Abstract: In this paper, the influence of the make-up air velocity as well as the position and area of the vents in an atrium is assessed both experimentally and numerically. In the experiments, the effect of different make-up air supply positions and inlet area on the fire-induced inner conditions and smoke-layer descent was studied by means of three full-scale fire tests conducted in a 20m cubic atrium. Detailed transient measurements of gas and wall temperatures, as well as pressure drop through the exhaust fans and airflow at the inlets were recorded. These data could be used as benchmark for future numerical validation studies. Later computational fluid dynamics (CFD) simulations of these tests were performed with the code Fire Dynamics Simulator (FDSv4). In the experiments, the lack of symmetry in make-up air vents and the large inlet area turn the flame and plume more sensitive to outer effects. However, no significant difference has been observed between the make-up air topologies assessed. Even make-up velocities higher than 1m/s, with symmetric venting topology, have not induced important flame or plume perturbations. In the numerical simulations, the predictions agree well with the experiments for the cases with larger make-up air openings. Poor agreement has been found for the case with the smallest inlet openings. [Copyright &y& Elsevier]

Abstract: The atrium concept allows the exploitation of daylighting by bringing natural light into the center of the buildings, thus enhancing a more even distribution of daylight. The configuration of interior balconies, however, is determined based on the purpose of the interior space and the use of the building, which may defeat the primary daylighting advantages inherent in the atrium concept. The authors have developed insights regarding the critical daylighting performance factors by evaluating the relative effect of various interior balcony configurations on illumination level and its distribution with different atrium geometries. For these, parametric measurements of illumination level with a scale model of a four-sided atrium building and various interior balcony configurations have been conducted under diffuse sky conditions within the sky simulator at a Texas university. This paper represents the atrium performance results in terms of daylight factor, Well index, balcony Well index, the configuration of interior balcony; and the results are compared with basecase atria without any interior balcony. As expected, Well index and balcony depth are the most significant factors in daylighting performance in atrium spaces with interior balconies. For the position not covered by balcony, adequate illumination can be achieved for circulation regardless of building Well index and balcony depth although it may be that involved well indices are relatively low. On the other hand, light attenuation on the position under balcony floor is up to 70–90%, in particular, when the Well index becomes higher than 1m and balcony floor becomes deeper than 3m. [Copyright &y& Elsevier]

Abstract: Solar penetration through the transparent envelope can severely deteriorate indoor thermal environment inside an atrium building particularly in tropical climates. This paper reports the application of two low-cost measures, namely high level internal solar blinds and water spray, to minimise overheating problems on the three levels inside the atrium of a guesthouse in Southern China, where summer is hot and humid. The blinds reduce direct solar penetration at the top of the atrium whilst the evaporative spray system cools down the glazed surfaces of the atrium envelope. A site test was undertaken over 10 consecutive days covering both overcast days and clear days in July 2004. Measurement of indoor thermal environmental parameters was conducted on three levels in the atrium and the recorded data represent the internal conditions: with and without internal blinds protection from solar, and with and without water spray. This study has shown that on hot and clear summer days, with water spray and without blinds the average air temperature difference from 1200 to 1800h between both first floor and second floor, and second floor and external were 5.7 and 1.7K, respectively; whilst with blinds and without water spray the average air temperature differences were 8.7 and 4.8K, respectively. [Copyright &y& Elsevier]

Abstract: The Fire Dynamics Simulator code is used to investigate the smoke movement in an atrium under fire scenario. At first, by comparing with experimental data of the atrium fire under low and high heat release rates, reasonable model constants of C s and Pr t and appropriate grid system are determined for simulating smoke movement in the atrium, the simulation results are in good agreement with those experimental data. Then, the performance of different smoke exhaust methods in the atrium is studied. Smoke filling processes are investigated under different natural and enhanced smoke exhaust methods. Simulated results show that natural smoke exhaust method is preferred when the smoke exhaust vents are located at the ceiling of the atrium. On the other hand, when the smoke exhaust vents are located on the walls of the atrium, the higher positions of the smoke exhaust vents are preferred. In addition, the influence of the fire source locations on the smoke spreading process is presented in this paper, three kinds of fire source locations are studied, they are central fire, side wall fire and corner fire. Results indicate that the descending process of the smoke layer is the slowest when the fire source is at the corner of the atrium. [Copyright &y& Elsevier]

Abstract: In this paper, the energy performance of a central atrium is investigated and compared with the energy performance of a courtyard with the same geometric proportions. The atrium and the courtyard design used for the analysis are square in plan and surrounded by the building on all four sides. The glazing type and percentage for the courtyard walls and atrium skylight are varied in the analysis. Weather data from four cities representative of climatic conditions of cold, temperate, hot-humid and hot-dry were used. The results show that, in general, the open courtyard building exhibits a better energy performance for the shorter buildings. As the building height increases, however, at some point the enclosed atrium exhibits a better energy performance. This “break even” point for the number of stories depends on different factors like glazing and climate parameters discussed above. [Copyright &y& Elsevier]

Abstract: This paper reports an investigation on the scenarios of the spill plume and the resultant natural filling in a full-scale atrium mock-up due to a retail shop fire. The study includes two aspects, i.e., the full-scale experiment and the numerical simulation. A spill plume model is proposed to predict the characteristic properties of the plume development in the atrium under a retail shop fire. Furthermore, to accurately predict the shop fire in the atrium, an improved zone model is developed combining the transport lag time model and the spill plume model. Besides validating the developed model by experiments, the case is also simulated by the established zone model, i.e., CFAST code, and the computational fluid dynamics model, i.e., FDS code. By both physical and numerical experiments, the process of natural smoke filling and the temperature rise in the atrium are investigated and well understood. It is found that a typical spill plume contains three regimes, i.e., the curved section out of the retail shop door, the line plume in the near field, and the axisymmetric plume in the far field. Predictions from the proposed empirical model for the spill plume and the resultant improved zone model compare favorably with the experiments. The study indicates that the atrium becomes very dangerous due to such shop fire if no smoke control employed. The ability of mechanical exhaust system in the atrium to mitigate the hazard of a retail shop fire is investigated as well. [Copyright &y& Elsevier]

Abstract: The concepts of green buildings and sustainable buildings are promoted actively in the developed countries. Targets are on protecting the environment, using less energy through natural ventilation provisions and daylight utilization, developing better waste management and taking water conservation into account. Architectural and building design, electrical and mechanical systems, and building management have to be upgraded. However, there are problems in dealing with fire safety, especially in complying with the existing prescriptive fire codes. An obvious example leading to hot arguments is the green or sustainable buildings with an atrium. Smoke spreading would give problems and evacuation design under smoke was identified to be a key issue. Providing more emergency exits might give a faster evacuation time, but would give security problems. An alternative solution is to install a smoke management system to keep the smoke layer high. Better designs can be achieved by integrating the evacuation time with the smoke filling time under different scenarios. Evacuation design can be improved by installing a smoke exhaust system. System performance by fire safety management would provide adequate safety. This point will be demonstrated in this paper. [Copyright &y& Elsevier]

This study investigates the release characteristics of neuropeptide Y (NPY) from young (10 weeks) and old (22 months) rat atrium. Levels of NPY release from samples of atrium were studied by organ perifusion. Rats were exposed to light:dark (LD) cycles of 12:12 or 18:6 and sacrificed at different circadian stages: 0, 4, 7, 12, 18, and 20 h after dark onset (HADO) for LD 12:12 or 0, 2, 3.5, 6, 15, and 22 HADO for LD 18:6. The heart was collected, and the right atrium was removed, weighed, and perifused with Krebs-bicarbonate buffer for 100 min, including a period of 50 min for stabilization of secretion rate. NPY concentrations released by atrium did not differ between the two age groups. NPY exhibited daily variations in concentrations in LD 12:12, with a peak during the end of scotophase, at 12 HADO, in both the young and old rats. These variations were strongly modified in LD 18:6, where the pattern of the release exhibited two peaks occurring during the two thirds of dark (3.5 HADO) and light (22 HADO) periods. This strongly suggests that the NPY rhythm is dependent on the environmental light:dark cycle. In this paper we show that NPY concentrations in the rat atrium exhibit daily variations, which are maintained with ageing. Moreover, photoperiod greatly influences NPY levels in the atrium. [Copyright &y& Elsevier]

This paper presents the field-measured energy performance of two common types of daylight-linked lighting control systems, continuous dimming and automatic on/off installed in two existing large atrium spaces located in Canada. The daylighting performance was evaluated based on the daylight contribution to the indoor illuminance and the amount of electrical lighting displaced by daylighting via the daylight-linked lighting control systems. Measured daylighting contribution to the space indicates that significant lighting energy savings can be achieved in atrium spaces if the daylight-linked lighting control system is appropriately selected, installed and commissioned throughout its existence. Results extrapolated from measurements collected during summer and winter indicate that as installed, the continuous dimming lighting control system provides 46% annual savings in electrical lighting consumption, while the automatic on/off saves between 11and 17% in lighting energy. These savings account for 68% of the lighting energy consumed during main occupancy for the continuous dimming system, and 31.5% for the automatic on/off. Operation irregularities such as a reduced dimming linearity and an incorrect adjustment of the phases of the dimming control system, as well as the inadequate location of the photocell controlling the automatic on/off lighting system, the improper maintenance of the skylight during winter and the oversizing of the lighting system reduced the energy efficiency of the lighting control systems by 30–65%. [Copyright &y& Elsevier]

An atrium is a central feature of many modern naturally ventilated building designs. The atrium fills with warm air from the adjoining storeys: this air may be further warmed by direct solar heating in the atrium, and the deep warm layer enhances the flow. In this paper we focus on the degree of flow enhancement achieved by an atrium which is itself ‘ventilated’ directly, by a low-level connection to the exterior. A theoretical model is developed to predict the steady stack-driven displacement flow and thermal stratification in the building, due to heat gains in the storey and solar gains in the atrium, and compared with the results of laboratory experiments.Direct ventilation of the atrium is detrimental to the ventilation of the storey and the best design is identified as a compromise that provides adequate ventilation of both spaces. We identify extremes of design for which an atrium provides no significant enhancement of the flow, and show that an atrium only enhances the flow in the storey if its upper opening is of an intermediate size, and its lower opening is sufficiently small. [Copyright &y& Elsevier]

This is one of two papers that outlines the methodology used to develop, through computer simulation, skylight design tools for thermal and energy performance of atriums in cold climates. The methodology identified important design alternatives that included skylight and atrium physical variables, and a series of thermal and energy performance outputs that may serve as selection criteria for an energy-efficient design. New prediction models were developed to overcome some computer-simulation limitations, which included models to deal with airflow between an atrium and its adjacent spaces and temperature stratification within an atrium space. The developed airflow network model is a technique used to predict the mutual influence between the atrium and its surrounding spaces without requiring additional geometrical information on the surrounding spaces. The developed temperature stratification model is consistent with airflow network models and the zone concept used in building thermal-simulation programs since it takes into account radiation (overlooked in airflow network models) and convection heat transfer at the same time. This was done through treating fictitious surfaces that separate the thermal zones in a similar way as real surfaces. Fictitious surfaces were assigned a high emissivity, high solar transmittance, high thermal conductivity and convection film coefficient of 10 W/m2 °C. These values were found to yield reasonable solar radiation absorption, convection and radiation heat balances for the real surfaces irrespective of the number of the thermal zones. The developed models were integrated into a simulation computer program, and then validated against field measurements of a case study atrium. The predicted indoor temperatures were within ±2°C of the measured ones in both winter and summer days. [Copyright &y& Elsevier]