Search Results (28)

This systematic review synthesizes passive and passive-first cooling strategies for greenhouses in hot–arid climates, organizing evidence across four domains: Airflow & Ventilation, Shading & Radiative Control, Thermal Storage & Ground Coupling, and Structural Design & Geometry. Drawing on the project corpus, we analyze 10–13 distinct techniques including ridge and side natural ventilation, windcatchers and solar chimneys, external shade nets, NIR-selective and transparent radiative-cooling films, and dynamic PV shading; earth-to-air heat exchangers (EAHE/GAHT), rock-bed sensible storage, phase-change materials (PCMs), and sunken or buried envelopes; as well as roof slope and shape, span number, and orientation. Across studies, cooling outcomes are reported as peak or daytime indoor air temperature reductions, defined relative either to outdoor conditions or to a control greenhouse, with the reference frame and temporal aggregation specified in the synthesis. Typical outcomes include ≈3–7 °C daytime reduction for optimized ventilation, ≈2–4 °C for shading and spectral covers while preserving PAR, ≈5–7 °C intake cooling for EAHE with winter pre-heating, and up to ≈14 °C peak attenuation for rock-bed storage under favorable conditions. Structural choices consistently amplify these effects by sustaining pressure head and limiting thermal heterogeneity. Performance is strongly context-dependent—governed by wind regime, diurnal amplitude, dust and UV exposure, and crop-specific light and temperature thresholds—and the most robust results arise from stacked, site-specific designs that combine skin-level radiative rejection, buoyancy-supportive geometry, and ground or latent buffering with minimal active backup. Smart controllers that modulate vents, shading, and targeted fogging or fans based on VPD or temperature differentials improve stability and reduce water and energy use by engaging actuation only when passive capacity is exceeded. We recommend standardized composite metrics encompassing temperature moderation, humidity stability, PAR availability, and water and energy use per unit yield to enable fair cross-study comparison, multi-season validation, and policy adoption. Collectively, the synthesized techniques provide a practical palette for improved greenhouse climate management under hot and arid conditions. Full article

Microbiological contamination in public buildings is closely linked to human presence, such as airborne bacteria, fungi, and particulate matter, which strongly influence indoor air quality (IAQ). This study examined the distribution of microorganisms in a museum building in relation to time of day, air-handling unit (AHU) type, and ventilation operating mode. Exhibition rooms without natural light relied entirely on a central heating, ventilation and air conditioning (HVAC) system. Microbiological contamination was assessed using Koch’s passive sedimentation method over a 24 h cycle for two AHUs (I and III) and selected rooms, while CO₂ levels were monitored as indicators of occupancy and ventilation demand in line with EN 16798-1:2019 and ASHRAE 62.1-2022. Although the demand-controlled ventilation system increased the outdoor air fraction from 40% to 70–100% during peak visitor density, localized increases in microbial contamination occurred. AHU I showed higher loads of Staphylococcus sp. and fungi, while AHU III exhibited pronounced fungal peaks influenced by elevated humidity from an open water reservoir. Psychrophilic bacteria reached 140–230 CFU·m⁻³, mesophilic bacteria 230–320 CFU·m⁻³, and fungi up to 740 CFU·m⁻³. Most CFU values remained below commonly referenced upper limits (<1000 CFU·m⁻³), but several peaks exceeded lower recommended thresholds, indicating a need for improvements. Enhanced filtration, humidity control, increased airflow during high occupancy, and reducing moisture sources in AHUs may mitigate microbial growth and improve IAQ in public buildings. Full article

Background: Children with congenital heart disease (CHD) are at substantially increased risk for respiratory infections, which occur more frequently and with greater severity than in healthy peers. This heightened vulnerability stems from multifactorial immune impairment, including defects in innate and adaptive immunity, chronic inflammation related to abnormal hemodynamics and hypoxia, reduced thymic function, and genetic syndromes affecting both cardiac and immune development. Viral pathogens—particularly respiratory syncytial virus (RSV), influenza viruses, and SARS-CoV-2—account for most infections, although bacterial pathogens remain relevant, especially in postoperative settings. Methods: This narrative review summarizes current evidence on infection susceptibility in children with CHD, the epidemiology and clinical relevance of major respiratory pathogens, and the effectiveness of available preventive measures. Literature evaluating immunological mechanisms, infection burden, vaccine effectiveness, and passive immunization strategies was examined, along with existing national and international immunization guidelines. Results: Children with CHD consistently exhibit higher rates of hospitalization, intensive care unit admission, mechanical ventilation, and mortality following respiratory infections. RSV, influenza, and SARS-CoV-2 infections are particularly severe in this population, while bacterial infections, though less common, contribute substantially to postoperative morbidity. Preventive options—including routine childhood vaccines, pneumococcal and Haemophilus influenzae type b vaccines, influenza vaccines, COVID-19 mRNA vaccines, and RSV monoclonal antibodies—demonstrate strong protective effects. New long-acting RSV monoclonal antibodies and maternal vaccination markedly enhance prevention in early infancy. However, vaccine coverage remains insufficient due to parental hesitancy, provider uncertainty, delayed immunization, and limited CHD-specific evidence. Conclusions: Respiratory infections pose a significant and preventable health burden in children with CHD. Enhancing the use of both active and passive immunization is essential to reduce morbidity and mortality. Strengthening evidence-based guidelines, improving coordination between specialists and primary care providers, integrating immunization checks into routine CHD management, and providing clear, condition-specific counseling to families can substantially improve vaccine uptake and clinical outcomes in this vulnerable population. Full article

The efficient recovery of waste heat is essential for improving sustainability in industrial and urban energy systems. This study presents the experimental evaluation of a passive heat recovery unit composed of finned thermosyphons and Bismuth Telluride (Bi₂Te₃) thermoelectric generators (TEGs). The primary objective was to characterize its simultaneous thermal recovery and electrical generation capabilities under airflow and temperature conditions simulating low-grade industrial exhaust streams. The system was tested in an open-loop wind tunnel simulating exhaust gases under air velocities of 0.6, 1.1, and 1.7 m/s. Heat was transferred to the TEGs through finned thermosyphons, enabling power generation via the Seebeck effect. The passive heat exchange mechanism successfully recovered up to 250.9 W of thermal power, preheating the inlet air by a maximum of 9.5 °C with a peak thermal effectiveness of 44.4%. Simultaneously, the system achieved a maximum temperature difference of 30.0 °C across the thermoelectric modules, generating a total electrical power of 163.7 mW (81.8 mW per TEG). This dual-purpose operation resulted in a maximum overall first-law efficiency of 9.38% and an electrical power density of 52.20 W/m² from the low-grade thermal stream. These results confirm the technical feasibility of this compact, passive, and maintenance-free design, highlighting its potential for integration into applications like district heating or industrial ventilation, where balancing thermal and electrical outputs is crucial. Full article

In the context of the energy crisis and the urgency of passive design in contemporary architecture, this study focuses on the Tujia-style Sanheyuan in southeastern Chongqing, China, which is highly adaptable to local climatic conditions. Using field surveys, architectural mapping, computational fluid dynamics numerical simulations, and multi-parameter comparative analysis, this study systematically explores the relationship between the geometric form of the Sanheyuan and its courtyard ventilation performance. Based on the Tujia construction scale modulus, this study summarizes the basic prototype of the Sanheyuan, analyzes the selection paths of its three sets of construction parameters, and constructs 48 typical courtyard models for wind environment simulation. By introducing five evaluation indicators—wind speed uniformity coefficient, proportion of strong wind zone area, proportion of calm wind zone area, and unit area wind rate—this study comprehensively assesses the impact of Sanheyuan design parameters on courtyard wind environment adaptability. This study concludes that specific spatial design parameters of the Tujia-style Sanheyuan significantly influence wind environment adaptability, offering quantitative guidance for climate-responsive and culturally informed architectural design. This study found that the optimal side room width-to-depth ratio is [1.00, 0.86, 0.83]; the optimal ridge height-to-stilt height ratio is [4.29, 8.00, 2.96]; and the optimal building footprint-to-side room area ratio is [3.01, 5.06, 4.75]. Full article

Natural ventilation could be established as an effective passive design strategy for increasing air changes per hour in a built environment. Modern air conditioning systems often fail to provide sufficient fresh air, potentially causing health issues for occupants. In contrast, natural ventilation offers an effective alternative for maintaining sufficient indoor air quality in buildings. This study explores the application of grouped airfoil arrays on building façades as an innovative passive design to enhance the air change rate. Numerical simulations were conducted to analyze various airfoil configurations, determining the most effective design for building a façade. Three groups, including symmetrical, semi-symmetrical, and flat-bottomed grouped airfoils, were selected according to their aerodynamic properties and potential impacts on airflow dynamics. For this purpose, a typical high-rise residential building was selected as a case study for field measurement and CFD simulation. The results indicated that symmetrical airfoil arrays could increase the air changes per hour (ACH) up to 23 times per hour with a wind velocity of 0.37 m/s at 10 m above ground, whereas their bidirectional performance ensured stable airflow regardless of wind direction. Although semi-symmetrical airfoil arrays maximize air capture and induce beneficial turbulence, the ACH within a residential unit was boosted up to 16 times per hour under the same outdoor wind velocity conditions. The ACH was 14 times per hour for the flat-bottom airfoils, serving as a comparative baseline and providing insights into the performance advantages of more complex designs. Full article

The timeshare is gradually becoming an essential global tourism operation model, especially in rural areas of China, where the leisure industry is developing rapidly. Meanwhile, the environmental issues of the rapidly growing timeshare-related building production have received widespread attention. The existing research on zero-carbon buildings considers carbon emissions as a constant value and cannot adapt to the impact of user changes during the operation phase. Constructing a low-carbon design applicable to timeshare is significant for controlling carbon emissions in the construction industry and responding to the environmental crisis. The practical carbon emissions of touristic apartments depend on the requirement changes in different customer clusters. The timeshare theory reflects the requirement change in different customer clusters based on the timeshare property ownership change. This paper focuses on a dynamic design strategy for zero-carbon building openings to reduce practical carbon emissions. Firstly, this research clarifies the primary customer clusters and conducts a touristic apartment unit model by timeshare property ownership. Then, this research clarifies the changes in customer requirements to analyze the spatial function changes in the operating phase. Finally, the study identifies six dynamic carbon emission indicators, such as the window-to-wall ratio, ventilation rate, and effective daylight area, and through passive design methods, provides 13 variable devices applied in the operating phase to control dynamic carbon emission indicators by customers. This paper also offers a flexible method to effectively decrease and accurately control carbon emissions by reducing the possible device utility. Full article

Objective: We sought to assess variations in pulse oximetry waveform amplitude (ΔP) and peak values (ΔS) separately during passive leg raising (PLR) and challenge plus maintenance crystalloid volume resuscitation over time in mechanically ventilated (MV) patients in shock. Methods: Variables were recorded and analayzed using previously described techniques. Findings were compared between the following: at baseline, during passive leg raising (PLR), with 0.9% normal saline administration (or removal), and applying tidal volume (Vt), peak, and mean airway pressure (Paw,peak and Paw,mean, respectively) and positive end-expiratory pressure (PEEP) as covariates in multifactorial logistic regression analysis. Results: Twenty patients with sepsis or septic shock were included in the analysis. Origins of sepsis varied. Their diagnoses upon admission to the intensive care unit included sepsis in nine (45%), septic shock (defined as the need for vasopressors) in nine (45%), and one (5%) rescuscitated from pulseless electrical activity following heroin overdose, all of whom were supported by volume control MV. Eleven patients required vasoactive drugs at the outset, of which seven were on norepinephrine. Three patients required surgical drainage or removal of necrotic tissue. Median ΔP and ΔS decreased, respectively, by 42% and 37% with PLR (p = 0.036 and p = 0.061, respectively). There were no significant changes in ΔP and ΔS between PLR and net fluid volume administered. Correction for body weight did not change these relationships. Application of Vt, Paw,peak, Paw,mean, and PEEP did not significantly influence these changes. Conclusions: Hemodynamic repsonse to slow fluid volume administration can be assessed by changes in the pulse oximetry waveform amplitude over time. The effects of mechanical ventilation are negligible. Full article

Background: Nirsevimab was indicated in a population level for all infants < 6 months during the 2023–2024 season in Andalusia (southern Spain). Our aim was to analyse the effect of nirsevimab in the reduction in complications in infants hospitalised for RSV bronchiolitis. Methods: A retrospective observational cohort study was conducted in nine relevant hospitals from all provinces of Andalusia, a region with over 9 million inhabitants. The study sample included 222 children, divided into two groups: infants administered with nirsevimab for passive immunisation (exposure) and infants not administered with nirsevimab. Clinical outcomes were analysed, including the use of respiratory support, the need for admission to paediatric intensive care unit (PICU), and duration of hospitalisation. Bivariate analyses were performed, and multivariable logistic regression models were designed to calculate adjusted odds ratios (ORa), and Cox regression models to calculate adjusted hazard ratios (HRa). Results: Bivariate analysis showed an association between passive immunisation with nirsevimab and a lower frequency of numerous outcomes. After adjustment for relevant covariates, multivariable models showed that the exposure (nirsevimab) reduced nasal cannula use by 64% (13–85%), invasive or non-invasive mechanical ventilation by 48% (1–73%), PICU admission by 54% (14–75%), length of hospitalisation by 30% (8–47%), and length of nasal cannula by 31% (7–49%). A higher risk of co-infection was observed in those immunised (aOR = 3.42, 95%CI: 1.52–7.68). Conclusions: Passive immunisation with nirsevimab may decrease the severity of RSV bronchiolitis in infants requiring hospitalisation, thus contributing tertiary prevention that extends beyond the prevention of RSV infection. Full article

Heart and lung sharing the same anatomical space are influenced by each other. Spontaneous breathing induces dynamic changes in intrathoracic pressure, impacting cardiac function, particularly the right ventricle. In intensive care units (ICU), mechanical ventilation (MV) and therefore positive end-expiratory pressure (PEEP) are often applied, and this inevitably influences cardiac function. In ventilated patients, the use of positive pressures leads to an increase in intrathoracic pressure and, consequently, to a reduction in the right ventricular preload and thus cardiac output. The clinician working in the intensive care unit must be able to assess the effects MV has on the heart in order to set it up appropriately and to manage any complications. The echocardiographic evaluation of the ventilated patient has the main purpose of studying the right ventricle; in fact, they are the ones most affected by PEEP. It is therefore necessary to assess the size, thickness, and systolic function of the right ventricle. In the mechanically ventilated patient, it may be difficult to assess the volemic status and fluid responsiveness, in fact, the study of the inferior vena cava (IVC) is not always reliable in these patients. In patients with MV, it is preferable to assess fluid responsiveness with dynamic methods such as the end-expiration occlusion (EEO) test, passive leg raise (PLR), and fluid challenge (FC). The study of the diaphragm is also essential to identify possible complications, manage weaning, and provide important prognostic information. This review describes the basis for echocardiographic evaluation of the mechanically ventilated patient with the aim of supporting the clinician in managing the consequences of MV for heart–lung interaction. Full article

The growing concern over indoor air quality (IAQ) and thermal comfort in classrooms, especially post-COVID-19, underscores the critical need for optimal ventilation systems to bolster students’ health and academic performance. This study explores the potential for improving indoor air quality and thermal comfort in the most energy- and cost-optimal manner using a demand-controlled ventilation (DCV) system coupled with a carbon dioxide control sensor. This is achieved through precooling via night purging in summer and by introducing warmer corridor air into the classroom in winter. The methodology employs both computer simulation and a real-world case study. The findings reveal that while natural ventilation in winter can achieve IAQ standard (EN 16798-1) thresholds for classrooms under favourable outdoor conditions, it results in uncontrolled and excessive energy loss. The retrofitted DCV system, however, maintained CO₂ levels below the recommended thresholds for at least 76% of the year depending on classroom orientation and only exceeded 1000 ppm for a maximum of 6% of the year. This study also indicates that utilising the external corridor as a sunspace can further enhance the system’s efficiency by preheating incoming air. This comprehensive study highlights the significant potential for integrating mechanical and passive solutions in school ventilation systems. This contributes to the attainment of the United Nations Sustainable Development Goal 11 and ensures healthier and more energy-efficient learning environments that benefit both students and the environment. Full article

Although glass façades have been on the market for over a century, new improvements, following sustainable standards, are still being invented. An improvement of the actively maintained CCF has occurred in passive maintenance with natural ventilation of the cavity and insulation glass unit placed on the external side, which has served as a true motivation for further research. To develop the idea, a new type of CCF was invented, followed by the creation of the software, whose purpose is to determine optimal CCF façade components. During this research, an experimental and mathematical model was made regarding the thermal behavior, later validated by the measurements on-site in Rugvica, Croatia. Using simplified but unconventional methods, numerous formulae and variables, a simulation of climatic loads onto the CCF was conducted. Validations of the thermal model were made during winter and summer periods for southern and western façade orientation, explaining how heat transfers from the environment to close cavity façade elements. It was found from the analysis that air temperatures of the façade elements follow the outer air temperature, by constant air exchange with the outer space. The results showed great potential with up to 3 °C (5–10%) of difference in experimental and calculated results, thus creating a basis for further improvement of the software with the addition of structural and hygric behavior of the façade element, regarding climate conditions. Full article

On average, houses including those in the tropics are responsible for almost 39% of the global carbon emission caused by non-renewables, first and foremost by fuel. Looking at the worldwide map of residential buildings’ contribution compared with commercial, the worldwide national maximum of 33.5% CO₂ of housing is caused by residential buildings in Uzbekistan. In an overwhelming number of most countries, their values are significantly lower, due to comparably lower energy demand than commercial buildings and because affordable homes increasingly use small PV to cater for their own basic needs. However, with the rising temperature and a likewise growing imperative to cool homes from about 30 °C onwards basically by split-unit air conditioners, the residential houses’ portion of CO₂-emission might dramatically increase to survive such more common hot periods in the future. In combination with air conditioners needing some airtightness, the first purpose of this entry is to show that bv 2050 in tropical regions, there will be no alternative to relatively airtight houses if the temperatures rise at the present speed. This is one alternative to an uncontrollable and life-threatening migration of millions of people to cooler but still livable regions in 2050. To trigger necessary changes toward homes that can better avert the heat, using the method of qualitative comparative content analysis, passive houses (PH) have emerged as adaptations to the tropical climate. Therefore, the second purpose of this in-depth study with the perspective of social science, is to reveal a comparative closer qualitative look at the tropicalized PH-approach. It is probably the most civilized building energy-saving strategy on the planet and can systematically keep the threatening increasing heat outside. However, before utilizing the concept, herein need to investigate why PH-technology as a whole concept with all its modules discussed earlier has been very slow to “go South” into the tropical region (the original PH will be referred to as “PH1”). The reason is that some qualitative differences of the more affordable and more simplistic tropicalized “PH2” make it easier and more realistic to penetrate the market, without letting go meaningful R&D-insights of PH1. As a probably facilitating future solution, the result is the triple-tabled option to utilise more synergies between the usually closed PH1 and the more open and flexibly naturally ventilated PH2. Unlike the PH-platform, ZEMCH is a related concept which tries to cater specifically to the significantly growing market for lower-income homes to go for carbonless energy. The conclusion is that scaling for residential buildings as mass products using passive house technology in combination with ZEMCH could turn out to become an important topic. It comprises the question in how far low or no carbon affordable homes based on the PH-concept in combination with ZEMCH-applications also may come into play as standard and to help mother Earth’s struggle for survival. Full article

This article deals with the investigation of wind effects on a façade of a rectangular residential building with explicit modelling of the windows for specific wind conditions. The external wind pressure coefficients were treated on the façade and at the places of the window sills, linings, and lintel for the direction of the wind from 0° to 90° with increments of 22.5°. For a detailed analysis, the CFD simulation using Ansys Fluent was used. The method selected for the CFD simulation solution and its setting (quality of meshing, horizontal homogeneity of the boundary layer, etc.) were verified by known results of similar objects. The purpose of this analysis is to show how important it is to consider wind effects to determine the suitable placement of passive ventilation devices. Research shows the potential optimal position of ventilation units in terms of favourable pressure distribution. Zones with negative pressure and corners or façades in a wake are not suitable for applying passive ventilation units. The results can serve as a basis for designers to achieve optimal comfort in residential buildings. Full article

Considering the comprehensive effect of building carbon emissions, cost savings is of great significance in nearly-zero-energy buildings (NZEBs). Previous research mostly focused on studying the impact of technical measures in pilot projects. The characteristics of different cities or climate zones have only been considered in a few studies, and the selection of cities is often limited. At times, only one city is considered in each climate zone. Therefore, this study selected 15 cities to better cover climate zone characteristics according to the variation in weather and solar radiation conditions. A pilot NZEB project was chosen as the research subject, in which the energy consumption was monitored and compared across different categories using simulated values by EnergyPlus software. Various NZEB technologies were considered, such as the high-performance building envelope, the fresh air heat recovery unit (FAHRU), demand-controlled ventilation (DCV), a high-efficiency HVAC and lighting system, daylighting, and photovoltaic (PV). The simulated carbon emission intensities in severe cold, cold, and hot summer and cold winter (HSCW) climate zones were 21.97 kgCO₂/m², 19.60 kgCO₂/m², and 15.40 kgCO₂/m², respectively. The combined use of various NZEB technologies resulted in incremental costs of 998.86 CNY/m², 870.61 CNY/m², and 656.58 CNY/m². The results indicated that the HSCW region had the best carbon emission reduction potential and cost-effectiveness when adopting NZEB strategies. Although the incremental cost of passive strategies produced by the envelope system is higher than active strategies produced by the HVAC system and lighting system, the effect of reducing the building’s heating load is a primary and urgent concern. The findings may provide a reference for similar buildings in different climate zones worldwide. Full article