Ventilation Performance Research Articles

Research on Optimization Design Strategies for Natural Ventilation in Living Units of Institutional Elderly Care Facilities Based on Computational Fluid Dynamics Simulation

As China transitions into a deeply aging society, the elderly population’s growth has driven a rapid increase in elderly care institutions and facilities during the “13th Five-Year Plan” period, rising by over 235% compared to the “12th Five-Year Plan”. The ongoing normalization of COVID-19 prevention measures has underscored the urgent need to improve natural ventilation in elderly care residential facilities. This study conducted empirical surveys to assess the current state of natural ventilation in typical elderly care facilities and analyzed the architectural elements influencing it. By examining the needs and preferences of the elderly for natural ventilation, two basic living space layout types were identified through typological analysis. Suitable CFD simulation software was then employed to model key elements, and effective methods to enhance ventilation were summarized. This study found that modifying the floor plan to reduce the depth of south-facing rooms to 8.4 m, relocating external openings to the center of the rooms, adjusting the ratio of ventilation openings to room area to greater than 1/12, and adding 0.5 m high windows facing internal traffic roads can significantly improve indoor ventilation while maintaining privacy. Furthermore, placing the main activity and resting areas of the elderly in well-ventilated zones with minimal drafts can enhance both comfort and ventilation effectiveness. The research provides a scientific basis and methodological guidance for the construction and renovation of elderly care residential facilities.

A novel evaluation method of measurement sensitivities on common faults in VAV HVAC systems

Today, a high volume of operation interval data can be efficiently captured by a diverse range of measurements including sensors, control signals and meters, which are deployed in building automation systems (BAS). Hence, advanced data analytics tools such as fault detection and diagnostic (FDD) can be developed to analyze the operational performance of heating, ventilation and air conditioning (HVAC) systems. In the past, enormous efforts have been made to develop various FDD approaches, assuming interval data contains essential information for identifying fault signatures. However, a “data rich, but information poor” phenomenon exists due to the fact that not all measurements are sensitive to faults in HVAC systems. This highlights a significant research gap, the lack of systematic analysis of measurement sensitivity to different HVAC system faults, which is vital for FDD development, measurement deployment optimization, and control system design. To address this gap, this study introduces a novel approach to assess the sensitivity of BAS measurements in relation to various HVAC fault types. We propose two sensitivity indices (SI), the SI of fault (SI_fault) and the global measurement SI (SI_measurement_global) to quantify measurement sensitivities. The SI_fault quantifies the measurement's sensitivity to a particular fault, while the SI_measurement_global assesses its sensitivity across all fault types. These indices integrate probability distributions, enhancing the interpretability and scalability. Utilizing the HVACSIM+ fault simulation dataset, which includes 15 common faults at varying severity levels and 89 different measurements within an HVAC system, we conducted an extensive analysis of measurement sensitivities by looking at the proposed SIs.

Multi-Scale Urban Natural Ventilation Climate Guidance: A Case Study in the Shijiazhuang Metropolitan Area

The rapid development of urbanization has caused obstructed urban natural ventilation and the contribution rate of urbanization is relatively high. Therefore, there is an urgent need for urban development planning that should respect natural ventilation and local climate to reduce negative impacts. By optimizing the urban construction layout to reduce obstruction and leave a passageway for wind to blow in, the natural ventilation environment could be improved. This paper presents a promising approach for natural ventilation planning at both the city and community scales. Based on the assessment of wind environment, heat island intensity, and ventilation potential, the results revealed that winds blowing from the western and northern mountainous area of Shijiazhuang play a natural ventilation inlet role which can provide clean air. The SSHI and SHI were mainly distributed within the Second Ring Road, which has a large proportion of the low ventilation potential level. Thus, six first-class ventilation corridors and thirteen secondary corridors were recommended, which were set to be adapted to the dominant wind direction. Subsequently, an urban climate analysis map (UCAnMap) was developed considering climate sensitivity, and planning recommendations were provided for different climate zones. The relationship between architectural spatial structure and ventilation efficiency was analyzed; the results revealed that increasing the height of the buildings will decrease the proportion of comfortable wind zones, and the overall ventilation efficiency will weaken, so the average building height of a typical block should be controlled within 45 m, which matches ventilation performance requirements. The ventilation efficiency of the block has a certain negative correlation with the building density, and as the building density decreased by more than 10%, the proportion of the comfortable wind zones could increase by 4–5%.

Improvement of Traditional Energy-Saving Cold Alley Spaces: Case Study of Shixiangyuan Garden Renovation and Expansion Project in Guangzhou

Traditional cold alleys have the ability to adapt to hot climates with cooling and insulation, which is a traditional design method that conforms to sustainable development. Due to the limited depth of space and the adoption of mechanical ventilation in most contemporary architectural design, this passive energy-saving method is gradually being ignored. In this study, we use ventilation measurement and simulation to explore the characteristics of ventilation performance in the cold alleys of the renovation and expansion project of Shixiangyuan Garden. The research, using anemometers and thermometers for measurement, aims to explore how Shixiangyuan Garden can utilize its existing environment and improve it to adapt to local conditions, and also discusses the methods of increasing the number of air vents to improve the overall ventilation performance of the alleys, as well as the effects of form changes caused by utilizing water and plants to supplement the soft interface. Although many studies have explored the mechanisms of cold alleys in traditional architecture, few have discussed the variance of cold alley forms that could adapt to the limited depths of newly constructed buildings. This study attempts to explore the potential for this through simulation. The purpose is to find new ways to inherit the sustainable advantages of cold alleys in new projects.

Ventilation improvement for effective protection of healthcare workers in negative pressure airborne infectious isolation room from viral aerosols

A negative pressure airborne infectious isolation room (AIIR) is the primary healthcare air contamination control system used for the treatment of severe respiratory infectious patients. Effects of the ventilation system configuration and conditions on airflow pattern, aerosol distribution and ventilation performance were investigated using computational fluid dynamics (CFD). The field measurement by SARS-CoV-2 environmental surface test was also conducted. The cycle threshold values from transcription polymerase chain reaction (RT-PCR) method showed inverse relation to the simulated number of particles trapped on the surfaces indicating a good agreement. Modification of the present AIIR to have alignment between air inlet and outlet where the aspect ratio of the air outlet, Width (W): Height (H) = 1:1 (Improved case: IC#1) showed a 78 % reduction of aerosol concentration in healthcare workers (HCWs) zones. Aerosol concentrations were increased when the openings of the air outlet were enlarged. Addition of air outlet led to large swirling air, resulting in more aerosols being trapped and suspended in the air. Results suggested that AIIR with alignment air inlet on the ceiling and air outlet at the wall over the patient's head with W:H = 1:1 be the most suitable configuration to maximize the ventilation performance and minimize exposure risk to aerosolized viral infection for HCWs. Air change rate plays a more important role than the differential pressure on the removal efficiency. The differential pressure value should be at least −2.5 Pa and the air supply rate 12 ACH for effective protection of HCWs in the negative pressure AIIR.

Physiological and hygienic assessment of a multilayer set of personal protective equipment against low temperatures made using membrane materials

Introduction. Advanced personal protective equipment (PPE) against low temperatures is a high–tech product created using the latest achievements of science, design designs, ergonomic, aesthetic solutions that determine its thermal protection properties. The use of membrane materials in PPE from low temperatures allows them to combine low weight and high thermal protection properties, low air permeability and sufficient vapor permeability necessary to ensure heat and moisture exchange between humans and the environment. The study aims to determine the thermal protection properties of various sets of multilayer workwear and indicators of heat and moisture exchange of volunteers when modeling professional activity at low air temperature. Materials and methods. The authors have conducted a study in a microclimatic chamber with the participation of six practically healthy male volunteers. The researchers have determined the thermal protection properties of multilayer workwear of various configurations in accordance with GOST R 12.4.185-99 and MUK 4.3.1894-04. As test samples, they have used pipes of three different configurations to protect against low temperatures, wind, water, general industrial pollution and mechanical influences, as well as short-term exposure to open fire. The assessment of heat and moisture exchange indicators of various PPE configurations was carried out by specialists when modeling work activities with measurements of the relative humidity level in the layers of the kits and the level of accumulated moisture in each element of the PPE. Results. The authors have determined the values of thermal insulation of the studied materials and the scope of their application. To assess heat and moisture exchange, two samples of PPE were selected, made using membrane and cotton fabrics with similar thermal insulation values. The analysis of the results of studies of moisture exchange indicators showed a slightly lower efficiency of moisture evaporation of the control sample. The indicator of the relative humidity of the air under the shelter space and between the layers of the package of materials and clothing has shown its informative significance for assessing the effectiveness of moisture transfer from the surface of the human body to the environment. Conclusion. The results of a physiological and hygienic assessment of a set of multilayer clothing made of membrane materials have shown that various combinations of its constituent elements make it possible to create kits that provide adequate protection for an employee in a wide range of air temperatures and wind speeds. The use of membrane materials in combination with structural elements (ventilation openings) provides a more efficient transfer of moisture from the skin surface to the external environment, as evidenced by the values of the relative humidity index of the air under the clothing space and between the layers of clothing. Ethics. The study was approved by the local Ethical committee of the Izmerov Research Institute of Occupational Health (Minutes of the meeting No. 6 dated 07/20/12)

Weak geostrophic wind driven ventilation in street canyons with trees and green walls: Cooperating or opposing dispersions of airborne pollutants?

Urban high-rise buildings and dense street canyons significantly disrupt synchronised wind flows, potentially exacerbating urban heat island effect. Fortunately, urban heat island effect can be mitigated by the green infrastructure in cities, particularly through the presence of roadside trees and green walls. However, the combined mechanisms of tree resistance, shading effects, and cooling effect, along with sensible thermal buoyancy flows within canyon ventilation and pollution dispersion, remain undisclosed. This study employs refined computational fluid dynamics numerical simulations to analyse airflow and pollutant dispersion within urban street canyons. Air exchange rate and pollutant retention time are employed to evaluate ventilation and pollutant dispersion, respectively, inside the street canyons.In scenarios with leeward green wall layout, higher tree canopy spread and trunk height lead to a shift in high pollutant concentrations from the region near the windward side to that near the leeward side of the typical canyon (H/W = 1). Conversely, in deep canyons (H/W = 5), most pollutants are retained near the bottom leeward side. Moreover, differences in pollutant dispersion between typical and deep canyons increase with with rising tree canopy spread. Additionally, higher tree canopy spread and trunk height values result in longer pollutant retention time, which are unfavourable for pollutant removal, and particularly limiting pollutant dispersion as street canyon depth increases. Similarly, increasing tree canopy spread reduces the difference in air exchange rate between windward and leeward green wall layout patterns. Regarding Richardson number variations —indicating thermal buoyancy effects—lower Richardson number values lead to reduced differences in pollutant retention time between typical and deep canyons. Furthermore, ventilation performance of the windward green pattern surpasses that of the leeward pattern. This research provides valuable insights for implementing green infrastructure to locally mitigate urban air pollution.

Study on the optimal layout of roof vents and rooftop photovoltaic of the industrial workshop

Roof vents are crucial for facilitating natural ventilation within industrial workshops. However, their substantial size and height can limit available roof space and create extensive shadow areas, thereby impeding the installation of photovoltaic (PV) systems on industrial roofs. This study quantitatively assesses the influence of roof vent positioning, morphology, and roof architecture on the natural ventilation efficiency of workshops with varying indoor heat sources. Subsequently, the study evaluates how different vent configurations affect the installable area for rooftop solar panels. Findings suggest that shifting from traditional roof ridge vents directly above a heat source to north-side vents inclined towards the roof can marginally decrease the ventilation flow rate by approximately 5 %, translating to a minor temperature rise of around 0.46 °C within the occupied zone. Nonetheless, the Predicted Mean Vote (PMV) thermal comfort indices remain consistent across scenarios. Notably, adopting north-side vents, either flush with the roof or inclined, can enhance the annual energy yield of the rooftop PV system by 15.49 % and 22.67 %, respectively, under equivalent solar irradiation. Thus, strategic adjustments to vent positioning, form, and roof design can substantially boost the photovoltaic system's power output without compromising the workshop's natural ventilation performance.

External Jet Nebulization and Measured Ventilator Performance.

During invasive ventilation, external flow jet nebulization results in increases in displayed exhaled tidal volumes (VT). We hypothesized that the magnitude of the increase is inaccurate. An ASL 5000 simulator measured ventilatory parameters over a wide range of adult settings: actual VT, peak inspiratory pressure (PIP), and time to minimum pressure. Ventilators with internal and external flow sensors were tested by using a variety of volume and pressure control modes (the target VT was 420 mL). Patient conditions (normal, COPD, ARDS) defined on the ASL 5000 were assessed at baseline and with 3.5 or 8 L/min of added external flow. Patient-triggering was assessed by reducing muscle effort to the level that resulted in backup ventilation and by changing ventilator sensitivity to the point of auto-triggering. Results are reported as percentage change from baseline after addition of 3.5 or 8 L/min external flow. For ventilators with internal flow sensors, changes in displayed exhaled VT ranged from 10% to 118%, however, when using volume control, actual increases in actual VT and PIP were only 4%-21% (P = .063, .031) and 6%-24% (P = .25, .031), respectively. Changes in actual VT correlated closely with changes in PIP (P < .001; R2 = 0.68). For pressure control, actual VT decreased by 3%-5% (P = .031) and 4%-9% (P = .031) with 3.5 and 8 L/min respectively, PIP was unchanged. With external flow sensors at the distal Y-piece junction, volume and pressure changes were statistically insignificant. The time to minimum pressure increased at most by 8% (P = .02) across all modes and ventilators. The effects on muscle pressure were minimal (∼1 cm H2O), and ventilator sensitivity effects were nearly undetectable. External flow jet nebulization resulted in much smaller changes in volume than indicated by the ventilator display. Statistically significant effects were confined primarily to machines with internal flow sensors. Differences approached the manufacturer-reported variation in ventilator baseline performance. During nebulizer therapy, effects on VT can be estimated at the bedside by monitoring PIP.

Balcony design to improve natural ventilation and energy performance in high-rise mixed-mode office buildings

Balconies have the potential to promote airflow and regulate solar heat gain, which can reduce energy usage for cooling in buildings. However, designing these elements can be challenging due to complex trade-offs for natural ventilation and energy performance, highlighting the need for advanced simulation tools to guide balcony design decisions. This study aims to evaluate the impacts of balcony design on natural ventilation and thermal and energy performance in high-rise mixed-mode office buildings in São Paulo, Brazil. To this end, an integrated method that involves computational fluid dynamics (CFD) and building performance simulations (BPS) is developed to identify optimal solutions. Through this method, the performance of 40 balcony designs is studied, comprising diverse alternatives for three balcony design parameters (width, depth, and location on the façade). Furthermore, the research is performed considering the balcony effects on two façade orientations (north and south), two wind incidences (windward and leeward), and three floor levels (upper, medium, and lower floors). Results are analysed through a sensitivity analysis, percentage of change and cross-analysis. The findings indicate that narrow and shallow balconies (2 m × 0.5 m) are the best design option for the south façade; they enhance natural ventilation and reduce energy consumption for cooling across all floor levels and balcony locations. Conversely, for the north, sun-facing façade, it is recommended to use wide and deep balconies (5 m × 2 m) to reduce solar gains and associated energy consumption for cooling, despite potential limitations in natural ventilation.

Optimizing air inlet designs for enhanced natural ventilation in indoor substations: A numerical modelling and CFD simulation study

This paper investigates the ventilation and heat dissipation performance of a 110 kV indoor substation under natural ventilation conditions using computational fluid dynamics (CFD). The objectives are to evaluate the influences of air inlet design parameters including location and size, and transformer load, on the airflow distribution, temperature field, and cooling efficiency. The study finds that staggered opposite inlets optimize cooling uniformity without airflow attenuation. Compared to a single inlet, the maximum transformer temperature is reduced by 1.3 °C and energy utilization increases by 9.1 % with staggered inlets. Increasing the inlet length ratio initially improves cooling until an optimal point (The length ratio is 1.10), while reducing the inlet height ratio decreases airflow and efficiency. With load increasing, the intake airflow rises but at a reduced rate, and the temperature difference can exceed 15 °C under high loads. In summary, optimizing inlet design enhances natural ventilation performance in indoor substations, but limitations exist at high loads, indicating supplemental mechanical ventilation may be required.

Ventilation performance evaluation of an operating room with temperature-controlled airflow system in contaminant control: A numerical study

This article investigates the efficacy of temperature-controlled airflow systems in modern operating rooms for contaminant control, a critical factor in preventing surgical site infections. We have conducted experimental measurements in an operating room equipped with temperature-controlled ventilation to map the airflow field and contaminant dispersion (airborne particles with diameters ranging from 0.5 to 1 μm). The results were used to validate the computational fluid dynamics code, which was then employed to simulate and examine different conditions, including contaminant release locations and air supply rates. Realizable k-epsilon and passive scalar models were utilized to simulate airflow and airborne particle phases. We assessed the airflow distribution and contaminant dispersion, utilizing indices such as ventilation and air change efficiency scales. The analysis provided quantitative insights into the distribution and removal of contaminants, as well as the speed at which the room air was replaced. Contamination was found to be effectively reduced when contaminants were released near exhaust outlets or under central unidirectional inlets. The presence of the operating table caused a big distortion of the central downward airflow, forming a horizontal air barrier at the periphery. Under this unique interior configuration, an appropriate air supply ratio between central and periphery zones was required to achieve optimal overall ventilation performance.

Opening windows as a supplementary ventilation strategy for large classrooms in a pandemic situation: Field measurements and simulation

The coronavirus disease 2019 (COVID-19) has led to significant global health emergencies in recent years, prompting widespread recommendations across various regions for opening windows in building codes. However, official guidelines have not adequately addressed the details of window opening arrangements related to the supporting evidence from existing literature. This study investigated the risk of disease outbreaks via respiratory transmission in large university studio classrooms. It examined the effectiveness of window-door opening strategies combined with mechanical ventilation in mitigating the infection risk of respiratory diseases in such spaces. A full-scale school ventilation performance test bed was used to measure indoor airflow and CO2 distribution patterns. Comparisons were made with the numerical simulation of exhaled viral emissions. A modified Wells-Riley equation was employed to calculate inhalation exposure and disease infection risks at the room level. Measurements showed that fresh air ventilation from the mechanical system was relatively low compared to existing standards, especially in pandemic situations. The results show that opening windows can lead to a decrease to low probabilities (below 5 %) of infection risk in 85.02 % area of a classroom over an 8-h period, which demonstrates that window-opening behavior is an effective supplementary strategy for large educational spaces with mechanically ventilated systems during emergencies when active measures are insufficient for diluting diseases. Furthermore, the study reveals that maximizing outdoor air rates by opening all windows may occasionally result in adverse indoor airflow redistribution, increasing virus load from 0.0382 to 0.8926 quanta/m3 near the virus source locations.

Periodic approaching flows and pollutant dispersion of a single-sided generic building with natural ventilation

In real urban environments, wind velocities often exhibit significant time-dependent variations. However, the impact of these fluctuations on ventilation performance is not frequently addressed in the literature. To accurately predict the building ventilation performance, this paper intends to elucidate the influence of the unsteady approaching flow. Four distinct inflows, characterized by periodic sinusoidal fluctuations, are evaluated using large-eddy simulation (LES). A single-sided building model with natural ventilation is constructed and validated through a wind tunnel experiment. Four periodic inflows consist of combinations of two frequencies (f = 0.1 and 0.3 Hz) and two amplitudes (A = 0.06 and 0.09). This paper mainly compares the results of airflow patterns and ventilation performance with those of stable inflows. The results indicate that periodic inflows cause greater fluctuations in the velocity fields on the leeward side. At higher frequencies and lower amplitudes, the vertical distribution of indoor bottom vortices is relatively dispersed. It shows that periodic flows lead to noticeable changes in the ventilation rate, with a deviation between instantaneous and average Q* ranging from 13.8% to 16.5%. Compared to the stable inflow, the impacts of periodic inflows on ventilation performance vary over time; 6% and 9% variations in incoming velocities result in deviations of up to 17.5% in ventilation rates. The frequencies and amplitudes of the periodic inflows do not exhibit a linear relation with ventilation rate. Therefore, it is prudent to be cautious about adopting averaged incoming wind velocities in predicting ventilation performance. This study helps in the more accurate prediction of single-sided natural ventilation.

Effects of internal wall design on cross-ventilation of an isolated building

Poorly designed internal walls deter natural ventilation of buildings, causing poor indoor air quality and exorbitant energy costs when mechanical ventilation systems are used. Although one can design internal walls with minimum adverse effects on natural ventilation by controlling height, width, location, and porosity of internal walls, less research has been done to date. This study investigated how these four parameters individually and collectively influence the cross-ventilation of buildings using Reynolds-average Navier–Stokes equation-based computational fluid dynamics simulations and the local and global sensitivity analysis. When considering individual parameters, the local sensitivity analysis revealed the positive correlation between internal walls' porosity and cross-ventilation, similar to previous studies. However, the global sensitivity analysis identified the location as the most influential design parameter for cross-ventilation. Furthermore, the global sensitivity analysis revealed nonlinear, non-monotonic, and interactive relations between cross ventilation and all parameters but porosity, highlighting the importance of evaluating all design parameters together and the difficulty in extrapolating the findings for idealized to actual internal wall designs. Based on the findings, this study proposes narrow internal walls with high porosities built away from ventilation openings as a basic internal wall design to maximize the cross-ventilation of buildings.

Annual performance of solar chimney for a multi-story building based on Modelica multizone model

Integration of solar chimney is an effective passive strategy for facilitating fresh air flow and offering significant potential for building energy conservation. This research evaluates the optimal design and control strategy for a six-story office building that includes a solar chimney, focusing on stack effect ventilation and energy performance throughout the year. The ventilation rates in different configurations of solar chimney are compared to meet fresh air requirements. The results indicate that the separated solar chimney ensures uniform airflow across each floor, with ventilation standard-reaching rates ranging from 79.5 % to 88.6 %. Furthermore, maximums of air flow rate occur at each floor, with critical cavity width values of 0.5 m, 0.4 m, 0.4 m, 0.3 m, 0.3 m, and 0.2 m on the 1st to 6th floor, respectively. Under the condition of equal cavity inlet area, air flow rates rise with the increasing length/width ratios. Finally, when the outdoor temperatures fall beyond the design range, controlling excessive ventilation generated by solar chimney leads to a 19.6 % reduction in total energy consumption over the year, with 71.5 % of the savings during winter.

A theoretical and numerical analysis of solar chimney in multi-storey atrium building

Current research efforts on solar chimney are much on those configurations with single space or single vent, hampering its applications in complex buildings. To expand its implementation, the viability of solar chimney in multi-storey atrium buildings was explored numerically and theoretically. It was known that its natural ventilation performance can fulfil the WHO requirements (i.e., 6 air change per hour, ACH) even under low solar radiation of 200 W/m2 if it is appropriately designed, such as cavity gap (d), cavity height (Hc), solar radiation (Q), and window width (W). Its natural ventilation rate was found to be positively linear to the exponential form of the analyzed factors in this study, including cavity gap (d0.63∼0.69), cavity height (Hc0.59∼0.60), solar radiation (Q0.42∼0.43), and window width (W0.14∼0.20). The impacts of cavity gap and solar radiation are relatively weaker for big space such as atrium than those scenarios with single-space ventilation in the literature. The volume of the connected space was found to affect its natural ventilation performance, where the obtained ventilation rate of 4-storey is averagely 5.1 % lower than those of 3-storey buildings. A theoretical model was developed and experimentally validated, for the first time, to predict the natural ventilation rate of solar chimney when it is applied to the atrium with multiple air inlets. It was also noticed that the same theoretical model can be applied to the atrium buildings with odd and even storeys, but the area coefficients are different. The research outcomes of this study confirm the viability of solar chimney in complex buildings and offer a theoretical foundation for its implementation.

Utilizing periodic boundary conditions to save computational resources for assessing building natural ventilation in urban areas

For the first time in literature, we innovatively conducted CFD simulations with periodic boundary conditions to predict coupled indoor-outdoor airflows for a full-scale 3D six-floor residential building unit in urban areas with uniformly building clusters. A few influencing parameters on building ventilation performance are comprehensively analyzed, including the impacts of the surrounding buildings, wind incident angle (θ), external opening designs, cross or single-sided ventilation modes, and indoor facilities. Ventilation evaluation is contingent on factors including air change rate per hour (ACH), the corresponding ACH of purging flow rate (ACHPFR), and age of air (τ).Results show that the efficiency of natural ventilation on each floor differs from previous research conclusions after considering the impacts of surrounding buildings. Single-sided ventilation is significantly less effective than cross-ventilation in all scenarios. Most cross-ventilation cases have one-order greater ACH and ACHPFR values compared to those with single-sided ventilation. The window-to-wall ratio on the windward and leeward sides can affect the natural ventilation rate of the corresponding rooms. A large leeward opening helps to increase the ventilation rate, especially for the rooms on the upper floor, but it decreases the ventilation for the rooms near the ground. Indoor furniture has an insignificant impact on outdoor airflow and natural ventilation efficiency.

Development and Safety Trial of the OstreaVent2™ Prototype for Mechanically Ventilated Adult Patients.

With the surge of COVID-19 infections, there were concerns about shortage of mechanical ventilator in several countries including the Philippines. To transform a locally made, low-cost, neonatal ventilator into a volume- and pressure-controlled, adult ventilator and to determine its safe use among ventilated, adult patients at the Philippine General Hospital. The modification of the neonatal ventilator (OstreaVent1) to the adult OstreaVent2 was based on the critical need for adult ventilators, in volume or pressure mode, in the Philippines due to the COVID-19 pandemic. The adult ventilator settings were calibrated and tested for two days to check for consistency and tolerance and then submitted to a third party for certification. Once certified, a safety trial of 10 stable adult patients on mechanical ventilator was conducted. The patients were placed on the OstreaVent2 for four hours while ventilator parameters, patient's vital signs, and arterial blood gases were monitored at baseline, during, and after placement on the OstreaVent2. A post-study chest radiograph was also done to rule out pulmonary complications, particularly atelectasis and pneumothorax. The prototype OstreaVent2 received an FDA Certification for Medical Listing after passing its third-party certification. Ten patients (60% male) recruited in the study had a mean age of 39.1 ± 11.6 years. Half of the patients had a diagnosis of non-COVID-19 pneumonia. During the 4-hour study period, the patients while on the OstreaVent2, had stable ventilator settings and most of the variabilities were within the acceptable tolerances. Vital signs were stable and arterial blood gases were within normal limits. One patient developed alar flaring which was relieved by endotracheal tube suctioning. No patient was withdrawn from the study. One patient who was already transferred out of the ICU subsequently deteriorated and died three days after transfer to the stepdown unit from a non-ventilator related cause. The new OstreaVent2 is safe to use among adults who need ventilator support. Variabilities in the ventilator's performance were within acceptable tolerances. Clinical and blood gas measurements of the patients were stable while on the ventilator.

Research and numerical assessment of design and construction errors in the swimming pool facility structures

Swimming pools are characterized by high humidity, high temperature, an aggressive environment caused by disinfection processes, high energy consumption, and extensive technical infrastructure. As a result, these facilities are at high risk of damage, including structural damage, which can have catastrophic consequences in extreme cases. Adequate ventilation plays a critical role in natatoria. The technical condition of swimming pool facilities should be regularly inspected to ensure that they are safe for the public. Various techniques can be used for this purpose. In the present study, a numerical analysis of ventilation performance and an assessment of the risks associated with design and construction errors in the ventilation system were conducted in a swimming pool building with a volume of 116,280.7 m3 and a surface area of 20,188.6 m2 in north-eastern Poland. Two scenarios were analyzed: the performance of the originally designed ventilation system and the performance of the ventilation system installed in the examined facility. The analyses were conducted with the use of computational fluid dynamics (CFD) tools in the FloVent program. Air distribution was determined by measuring ventilation parameters and conducting smoke tests in analyzed natatorium, and the obtained data were consistent with the results of the numerical analysis. The analyzed scenarios were compared to identify the risks associated with inadequate ventilation in swimming pools. A significant decrease in air supply led to local increases in air velocity and worsened thermal comfort parameters in the real-world facility. In addition, the decrease in air supply induced changes in air distribution and prevented air streams from reaching all parts of the natatorium. Some areas were inadequately ventilated, and condensed water vapor settled on the building’s glass facade and the roof, posing a direct threat to structural elements. The results of the numerical analysis were congruent with on-site measurements, which indicates that CFD tools are highly useful for assessing ventilation systems in swimming pools. These tools can be used to analyze ventilation performance and optimize the proposed solutions already at the design stage. The applied tools enable designers to eliminate construction errors and optimize a building’s structural safety, performance, and energy efficiency.