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Air conditioning systems can play a positive or negative role in the spread of COVID-19 infection. The importance of sufficient outdoor air changes in buildings was highlighted by the World Health Organization, therefore these should be guaranteed by mechanical ventilation systems or adequate air conditioning systems. The proposed case study concerns the optimal number of outdoor air changes to limit COVID-19 contagion for a school building in Central Italy. The Wells–Riley model is used to assess the risk of airborne infection, while energy consumption is calculated by a dynamic energy simulation software. The scope of the paper offers an innovative method to define the optimal ventilation strategy for the building's HVAC system design to reduce the risk of infection with limited increases in energy consumption and greenhouse gas emissions. Results show that the desirable approach is the one in which the same low value of contagion risk is set in all rooms. This new approach results in significant energy savings, compared to the most common ones (setting the same high outdoor air rates for all rooms) to counteract the risk of infection. Finally, the zero-emission building target is verified by introducing a suitable photovoltaic system to offset pollutant emissions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Exposure to radon gas in households presents serious health risks, including an increased likelihood of lung cancer. Following the COVID-19 pandemic, the change in individual habits has led to more time spent in indoor environments with remote activities; thus, the need to raise the awareness of air quality in dwellings and to mitigate the exposure of inhabitants to radon has emerged. This study investigated radon gas concentrations in the air of Latvian dwellings. RadTrack2 passive detectors were deployed in a representative sample of households across 106 municipalities of Latvia (98% of the territory), yielding data from 487 households (973 detectors). The data revealed a median radon concentration of 52 Bq/m3 (Q1 and Q3 were 29 and 93 Bq/m3), with the majority of samples (95.6%) falling below the national reference limit of 200 Bq/m3. The building type and presence of a cellar significantly impacted radon levels, with structures lacking cellars and older buildings exhibiting higher concentrations. Mechanical ventilation proved to be more effective in reducing radon levels, compared to natural ventilation. These findings emphasize the necessity of proactive measures to mitigate indoor radon exposure and to ensure the well-being of occupants. Additionally, the dissemination of research data on radon exposure through open-access scientific publications is vital for raising awareness and implementing effective mitigation strategies. [ABSTRACT FROM AUTHOR]

Most studies on Chinese dormitories are carried out in summer, while few focus on a transition season or winter. This study evaluated the air quality of a student dormitory in a university in the Beijing area by using a questionnaire survey and on-site measurements. The CO2 concentration was used as an indoor air quality evaluation index to characterize the freshness of the air, and different window opening conditions in the dormitory were simulated, with corresponding improvement plans proposed. The results of this study revealed that the air quality and thermal comfort of the student dormitories during a transition season and winter fell short of expectations. According to the survey, students who opened their windows frequently had a better subjective perception of the air quality. However, due to the large temperature difference between day and night, more than 80% of the students felt too cold when opening the windows. For daytime conditions, the area of unilateral ventilation window opening should not be less than 0.39 m2, the area of bilateral ventilation window opening should not be less than 0.13 m2, and the time taken to close the windows and doors should not exceed the maximum ventilation interval. Empirical equations were fitted for nighttime conditions based on the CO2 concentration, number of people in the room, and window opening area, resulting in a reasonable window opening area of 0.349 m2~0.457 m2. In sum, this study assessed the air quality status within typical university dormitories across varying seasons, gaining a clear understanding of how different ventilation strategies and occupant densities influence air freshness and thermal comfort. Based on these insights, a practical and optimized window area recommendation was formulated to enhance the indoor environmental quality in these dormitories. [ABSTRACT FROM AUTHOR]

In Poland and other countries in Central Europe, residential buildings from the second half of the 20th century dominate, which have recently undergone deep thermomodernisation. Research on the retrofitting of residential buildings has focused mainly on energy efficiency, with only a few studies on indoor air quality. The aim of this study was to present a comparative analysis of the impact of five ventilation scenarios (three natural and two mechanical) on CO2 concentration and energy demand for heating and ventilation in residential spaces of a multi-family building located in Poland. The analyses were based on the results of building performance co-simulation using the EnergyPlus and CONTAM programs carried out under dynamic conditions with a 5 min time step for the entire heating season. The calculations took into account the instantaneous occupancy variability of twenty apartments. In the buildings equipped with new tight windows, the natural ventilation system provided extremely low air exchange (on average 0.1 h−1) and poor indoor air quality (average CO2 concentration at the level of 2500 ppm). Opening windows to ventilate the rooms generated a multiple increase (up to 8 times) in heating demand during these periods, but average CO2 concentration was on the level of 930 ppm. The use of mechanical ventilation was profitable both in terms of energy savings (at the level of 50%) and improvement in the indoor air. [ABSTRACT FROM AUTHOR]

The air quality in classrooms significantly impacts school children's health and learning performance. It has been reported worldwide that classroom air quality does not meet the required standard and actions are pledged for improvement. However, it poses a challenge for decision-making in terms of prioritising taking-up measures. The aim of this study is to propose a method of identifying the action measures for improving classroom air quality and prioritising them. Case studies in the UK and China were conducted, and the key measures were identified through literature studies, open-ended questionnaire surveys, and workshop discussions, which are classified into three categories: B1, policy; B2, technology; and B3, information sharing. The analytical hierarchy process (AHP) is applied in the prioritisation of the action measures. A total of 138 teachers and parents from China and the UK participated in this case study. The genetic algorithm-optimised Hadamard product (GAOHP) method is applied to justify the consistency ratio (CR) within the required threshold value in order to ensure the consistency of the subjective perception and the accuracy of comparative weights. The results show that item B2, technology, is the most desired measure by both Chinese and British parents and teachers, despite the deviation from the optimal choice in China and the UK. Among the proposed action measures, the UK respondents strongly expected air purifiers with natural ventilation as opposed to their Chinese counterparts preferring to share the real-time status of classroom air quality. Our work will provide strong support for the subsequent selection of indoor air quality improvement strategies for schools. [ABSTRACT FROM AUTHOR]

Previous studies showed that opening windows could help with kitchen ventilation in pollutant removal. However, no studies have systematically examined the impacts of window positions on kitchen hood performance, and there is insufficient information on indoor airflow characteristics and pollutant distribution from makeup air through open windows. Therefore, the objective of this study was to use a validated computational fluid dynamics approach with CO2 as an indoor air quality indicator (a surrogate for cooking emissions) to understand the impacts of exhaust flow rate and the window opening position on the flow characteristics, concentration distribution, and capture efficiency (CE) of the hood. We conducted four-point validation tests of the numerical models based on CO2 concentration and temperature measurements under steady-state conditions. The validated models were subsequently used in simulations to understand the effects of six different window opening positions and the two exhaust flow rates on exposure. We found that the CO2 concentration could be better reduced by having windows open at the higher location. Generally, the front windows were more effective with CE > 80 % , followed by the back and the side windows, respectively. We also found that as the exhaust flow rate increased from 6.72 to 12.16 m3/min, CE reached >75% for all window positions, where the most significant increase was 1.58 times for the lower side window. To sum up, changing the relative position of the window and the exhaust hood could help disperse the incoming airflow from the window, improve the kitchen's overall ventilation, and reduce pollutant concentration. [ABSTRACT FROM AUTHOR]

Traditional buildings have a central role to play in Europe's plans to be the first climate-neutral continent by 2050, with the building sector being the single largest energy consumer in the EU with 40 per cent of total energy use. Seventy-five per cent of the existing housing stock is energy inefficient with minute numbers renovated each year. Existing buildings offer huge potential for energy use reduction. Research has shown that a historic retrofit can emit less carbon compared to demolishment and rebuilding. Reductions in carbon emissions of up to 62 per cent were observed across a body of case studies by Historic England, including a 95 per cent reduction in the mews case study described in this paper. Moreover, carefully managed thermal retrofits, taking a 'whole house approach', have many benefits, including improved indoor comfort and air quality as well as reduced operational costs. These are factors which are fundamental in ensuring the continued use of historic constructions while improving their standards of preservation and durability. Thermally upgrading traditional building is still a much-debated topic. Inappropriate thermal interventions with unsuitable materials and finishes can have unforeseen consequences, resulting in building damage and a reduction in internal comfort, health and well-being. This paper aims to contribute to this discussion by providing an overview of key considerations when thermally upgrading the walls of traditional buildings while preserving unique characteristics and functionality. Advantages of adopting thermal mortars such as cork lime are put forward, and their potential efficacy is discussed, concluding with a case study focusing on the deep retrofit of a London mews within a conservation area. [ABSTRACT FROM AUTHOR]

Before the COVID-19 pandemic, ventilation in buildings was not always given its due importance. The World Health Organization has highlighted the important role of air exchange with the outdoors in improving the air quality in buildings; buildings should, therefore, be equipped with mechanical ventilation or adequate air conditioning systems. This paper aims to investigate different retrofit solutions for air conditioning, evaluating them in terms of energy consumption and cost and the impact of increased outdoor air exchange rates on countering the propagation of COVID-19; the latter is the main novelty of the paper. As a case study, we take an existing office building located in Central Italy that was previously not equipped with a mechanical ventilation system (a system with primary air was introduced during the study). The energy analysis was conducted using dynamic simulation software after validation through energy bills; energy and economic analyses were conducted considering different external-air exchange rates. An optimal number of outdoor air changes was found to mitigate the risk of COVID-19 infection, a finding in line with the international literature. The increase in air changes with outdoor air leads to a rise in energy consumption and costs. These values were evaluated for different air conditioning systems and operational schedules. These drawbacks can be made less significant by combining interventions in the system with energy-efficiency measures applied to the building envelope. [ABSTRACT FROM AUTHOR]

Predicting indoor airflow distribution in multi-storey residential buildings is essential for designing energy-efficient natural ventilation systems. The indoor environment significantly impacts human health and well-being, considering the substantial time spent indoors and the potential health and safety risks faced daily. To ensure occupants' thermal comfort and indoor air quality, airflow simulations in the built environment must be efficient and precise. This study proposes a novel approach combining Computational Fluid Dynamics (CFD) simulations with machine learning techniques to predict indoor airflow. Specifically, we investigate the viability of employing a Deep Neural Network (DNN) model for accurately forecasting indoor airflow dispersion. The quantitative results reveal the DNN's ability to faithfully reproduce indoor airflow patterns and temperature distributions. Furthermore, DNN approaches to investigate indoor airflow in the residential building achieved an 80% reduction in the time required to anticipate testing scenarios compared with CFD simulation, underscoring the potential for efficient indoor airflow prediction. This research underscores the feasibility and effectiveness of a data-driven approach, enabling swift and accurate indoor airflow predictions in naturally ventilated residential buildings. Such predictive models hold significant promise for optimizing indoor air quality, thermal comfort, and energy efficiency, thereby contributing to sustainable building design and operation. [ABSTRACT FROM AUTHOR]

In light of pressing global health concerns, the significance of indoor air quality in densely populated structures has been emphasized. This research introduces the Mimosa kinetic façade, an innovative design inspired by the adaptive responsiveness of the Mimosa plant to environmental stimuli. Traditional static architectural façades often hinder natural ventilation, leading to diminished air quality with potential health and cognitive repercussions. The Mimosa kinetic façade addresses these challenges by enhancing effective airflow and facilitating the removal of airborne contaminants. This study evaluates the façade's impact on quality of life and its aesthetic contribution to architectural beauty, utilizing the biomimicry design spiral for a nature-inspired approach. Computational simulations and physical tests were conducted to assess the ventilation capacities of various façade systems, with a particular focus on settings in Bangkok, Thailand. The study revealed that kinetic façades, especially certain patterns, provided superior ventilation compared to static ones. Some patterns prioritized ventilation, while others optimized human comfort during extended stays. Notably, the most effective patterns of the kinetic façade inspired by the Mimosa demonstrated a high air velocity reaching up to 12 m/s, in contrast to the peak of 2.50 m/s in single-sided façades (traditional façades). This highlights the kinetic façade's potential to rapidly expel airborne particles from indoor spaces, outperforming traditional façades. The findings underscore the potential of specific kinetic façade patterns in enhancing indoor air quality and human comfort, indicating a promising future for kinetic façades in architectural design. This study aims to achieve an optimal balance between indoor air quality and human comfort, although challenges remain in perfecting this equilibrium. [ABSTRACT FROM AUTHOR]

To reduce national greenhouse gas emissions, the South Korean government has encouraged new energy businesses and implemented policies to reduce energy consumption in buildings, and aims to construct all new buildings as zero-energy buildings by 2025. According to the promotion of policies on passive houses and zero-energy buildings, the thermal insulation and airtight performance of new buildings have been further enhanced. However, to enhance indoor comfort and air quality in new airtight buildings, it is critical to secure an adequate amount of ventilation. Heat recovery ventilators (HRVs) in South Korea have been used for more than 20 years as high-efficiency energy equipment; however, the high-efficiency standard 20 years ago (cooling efficiency 45%, heating efficiency 70%) is still being employed without any change. Most HRVs in the Korean market either meet or exceed this standard. This study examined HRV performance changes from 2010 to 2020 based on the data of 847 HRV performance certifications given by a certification agency. It also analyzed how institutional strategies and related laws contributed to the enhancement of such performance. As HRVs in South Korea are only required to satisfy the pre-defined efficiency criteria, the development and use of HRVs focus more on cost reduction rather than efficiency enhancement. Under such market conditions, it is challenging to research and design highly efficient HRVs along with customer satisfaction. If better market conditions are offered that would welcome HRVs with higher efficiency, the development of better HRVs, as compared to those analyzed in this research study, would be possible. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of different ventilation methods in reducing indoor air pollutants in newly constructed residential buildings, focusing on indoor air quality (IAQ) in Dubai. The paper highlights the growing concern for IAQ in response to residents' increasing awareness of their well-being and environmental sustainability. The study examines the concentrations of formaldehyde (HCHO), volatile organic compounds (VOCs), and total volatile organic compounds (TVOC) in bedrooms and living rooms before and after implementing various ventilation methods during the construction phase. The findings indicate that mechanical exhaust ventilation, mainly through bathroom and kitchen exhaust fans, was highly effective in reducing HCHO levels. Combining kitchen and bathroom exhaust fans demonstrated the most significant reduction in HCHO concentrations. Similarly, reductions in VOCs, such as ethylbenzene, toluene, and xylene, were observed with different ventilation methods. Natural ventilation also proved effective in reducing pollutant concentrations. The results emphasize the importance of implementing appropriate ventilation strategies to improve IAQ in residential buildings. However, the study acknowledges the limitations of a single-location measurement and recommends further research to validate the findings across different building types and locations. Additionally, long-term studies are necessary to assess the sustained effects of ventilation methods on IAQ. The study highlights the significance of addressing IAQ concerns in residential buildings and suggests potential research directions to explore other ventilation strategies and their energy efficiency implications. Ultimately, this research contributes to developing healthier and sustainable living environments by promoting effective ventilation strategies to mitigate indoor air pollutants. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has inflicted major economic and health burdens across the world. On the other hand, the potential airborne transmission of SARS-COV-2 via air can deeply undermine the effectiveness of countermeasures against spreading the disease. Therefore, there is an intense focus to look for ways to mitigate the COVID-19 spread within various indoor settings. This work systematically reviewed articles regarding airborne transmission of SARS-COV2 in various indoor settings since the onset of the pandemic. The systematic search was performed in Scopus, Web of Science, and PubMed databases and has returned 19 original articles carefully screened with regard to inclusion and exclusion criteria. The results showed that the facilities, such as dormitories and classrooms, received the most attention followed by office buildings, healthcare facilities, residential buildings, and other potential enclosed spaces such as a metro wagon. Besides, the majority of the studies were conducted experimentally while other studies were done using computer simulations. United States (n = 5), Spain (n = 4) and China (n = 3) were the top three countries based on the number of performed research. Ventilation rate was the most influential parameter in controlling the infection spread. CO2 was the primary reference for viral spread in the buildings. The use of natural ventilation or a combination of mechanical and natural ventilations was found to be highly effective in the studies. The current work helps in furthering research on effective interventions to improve indoor air quality and control the spread of COVID-19 and other respiratory diseases. [ABSTRACT FROM AUTHOR]

Clothing can absorb fine particulate pollutants from the atmosphere outdoors and then release them after entering the room in a form similar to three-handed smoke. In this study, the experimental site in Zhengzhou, a typical city with heavy pollution in central China, was used to investigate the adsorption and diffusion patterns of three different fabrics of polyester, polyester-cotton, and cotton clothing for fine particle pollutants, to guide people's behavior patterns and indoor air distribution, and to reduce indoor pollution exposure. The results showed that when garments of three different fabrics were exposed to moderate and heavy PM2.5 pollution for 1 h, 2 h, and 3 h, respectively, and then transferred to the diffusion chamber, polyester always released the highest PM2.5 concentration to indoor air during the same release cycle, followed by cotton and polyester-cotton. In addition, the concentration of indoor air pollutants will be periodically affected by the diffusion of fine particulate adsorbed by clothing fabrics. With the increase in outdoor pollution and exposure duration, the indoor PM2.5 concentration takes longer to stabilize at certain levels after the clothing is transferred to the indoor side. Finally, the comparison of natural ventilation experiments proved that it is not feasible to rely solely on natural ventilation to improve the influence of clothing pollution sources on indoor air quality. [ABSTRACT FROM AUTHOR]

The study presents a method to determine window opening time and frequency, considering window characteristics, indoor and outdoor conditions, and room occupancy. Results reveal that opening time correlates with room surface and occupancy but diminishes with larger window areas and favourable discharge coefficients based on window types. Additionally, in windless conditions, opening time decreases as the indooroutdoor temperature difference increases. [ABSTRACT FROM AUTHOR]

The recent Coronavirus Disease 2019 pandemic has highlighted the importance of indoor ventilation. In particular, ventilation is crucial in residential spaces and workspaces, where people spent most of their day. Natural ventilation is a cost-effective method for improving indoor ventilation. It can provide safe and comfortable residential and working environments without additional energy consumption. In this study, the ventilation performance was experimentally studied by measuring the concentration of ultrafine particulate matter according to the opening conditions of the windows and door of an office model in a wind tunnel. Furthermore, the internal flow structure in the office model was quantitatively analyzed through particle image velocimetry to determine the factors that affected the ventilation performance. The mean velocity inside the model and the ventilation performance increased with the opening angle of the windows. In particular, the opening condition of the door strongly affected the ventilation performance. This study is expected to provide a guideline for effectively improving the ventilation performance in indoor spaces. [ABSTRACT FROM AUTHOR]

Most of Australia's classrooms are equipped with operable windows for ventilation, and occupant-controlled air-conditioners that do not provide fresh air. This can result in insufficient ventilation and high indoor CO2 levels, which comes to the detriment of occupant productivity and health. In this paper, we report on the results of a field study in which we captured indoor CO2 levels in five classrooms at a school in Victoria, Australia. The study consisted of three measurement periods: (1) First, CO2 levels were measured pre-COVID pandemic; here, the readings exceeded the recommended ASHRAE threshold of 1,000 ppm for 73% of occupied hours, while levels exceeded 2,000 ppm 37% of the time. (2) Then, we captured data after the teachers had been informed of the poor indoor air quality (IAQ) and the state government introduced COVIDSafe measures; the impact was significant, with now only about 16% of readings above 1,000 ppm and values almost never exceeding 2,000 ppm. (3) Finally, we installed devices that gave the occupants visual feedback when CO2 levels were high, prompting them to open the windows and doors; this further improved the classrooms' IAQ, with now just 13% of readings above 1,000 ppm. Our study suggests that, while relying on uninformed occupants to operate windows can lead to poor IAQ due to insufficient ventilation, it is possible to considerably influence occupant behaviour through education and feedback devices. While these interventions alone did not mitigate the problem of inadequate ventilation entirely, they were sufficient to keep CO2 levels within a generally healthy range. Considering the large energy savings that are possible by foregoing mechanical ventilation, we suggest that natural ventilation is a feasible operation method for school buildings in temperate climates, as long as occupants are informed about the importance of ventilating, by providing them with CO2 feedback devices. [ABSTRACT FROM AUTHOR]

Infectious diseases such as the COVID-19 pandemic have necessitated preventive measures against the spread of indoor infections. There has been increasing interest in indoor air quality (IAQ) management. Air quality can be managed simply by alleviating the source of infection or pollution, but the person within a space can be the source of infection or pollution, thus necessitating an estimation of the exact number of people occupying the space. Generally, management plans for mitigating the spread of infections and maintaining the IAQ, such as ventilation, are based on the number of people occupying the space. In this study, carbon dioxide (CO2)-based machine learning was used to estimate the number of people occupying a space. For machine learning, the CO2 concentration, ventilation system operation status, and indoor–outdoor and indoor–corridor differential pressure data were used. In the random forest (RF) and artificial neural network (ANN) models, where the CO2 concentration and ventilation system operation modes were input, the accuracy was highest at 0.9102 and 0.9180, respectively. When the CO2 concentration and differential pressure data were included, the accuracy was lowest at 0.8916 and 0.8936, respectively. Future differential pressure data will be associated with the change in the CO2 concentration to increase the accuracy of occupancy estimation. [ABSTRACT FROM AUTHOR]

In this study, a controller method for window opening was developed to naturally ventilate a classroom with 30 occupants. The aim was to improve indoor environment quality and limit the probability of COVID infection risk simultaneously. The study was based on a building performance simulation using combined EnergyPlus, CONTAM, and Python programs. Seven cases with automatically opening windows were considered. Opening window parameters were optimized by genetic algorithms. It was shown that the optimized controller with indoor environment functions improved classroom ventilation and considerably decreased CO2 concentration compared to a reference case where the windows were opened only during breaks, and the controller also improved occupants' thermal comfort. However, there was a noticeable increase in energy demand, caused by the increased air change rate. Introducing the probability of infection risk function to the controller did not reduce the transmission risk substantially, and the probability of infection transmission was high for 80% of the classroom occupancy time. The risk of infection changed only when additional actions were taken, such as introducing face masks, indoor air cleaners, or reducing the number of students present in the classroom. In these cases, it was possible to prevent the infection transmission for more than 90% of the lecture time (R0 < 1). [ABSTRACT FROM AUTHOR]

The buildings consume nearly 55% of global electricity. As people are forced to spend more time indoors after pandemic COVID 19, energy efficient, well ventilated, adequate indoor air quality became critical for their health. The household energy consumption is mostly for heating but also for cooling in Kosovo. Aiming to improve energy efficiency, a passive cooling strategy can be applied by using a natural ventilation as the most essential method. However, that requires an analysis of different factors such as positions and the sizes of the openings within one area, the specific period used for ventilation, and the external temperatures and conditions. In this work, the computer application Optivent 2 was used to analyze a generic airflow strategy and evaluate the decisions regarding the feasibility of cooling with natural ventilation for a single house in Kosovo during the warmest month of the year (i.e. August). The results prove that the natural ventilation during the day at the houses, which the areas have only one-sided openings, is effective only for fresh air flow but not sufficient for cooling purposes. When the openings are designed on the opposite walls of the rooms or areas, the conditions will enable that through cross ventilation, the area will be cooled at the same time, by achieving up to 90% of the accessibility limits of comfort, both during the day and nights, at different scenarios on the warmest summer months in Kosovo. These findings will help the architects of Kosovo to identify the proper and most effective passive designs strategy, when it comes to buildings cooling during the summer, in order to achieve the maximal benefit of their designs and the operation of their designed building. [ABSTRACT FROM AUTHOR]

The role of interzonal airflows is especially pronounced in naturally ventilated buildings. In such buildings, reversed airflows in the ventilation stacks might occur as well. This affects the air exchange rate and contaminant distribution in buildings. A significant increase in carbon dioxide concentration is a characteristic phenomenon for poorly ventilated rooms. This paper demonstrates the application of metabolic carbon dioxide concentration measurements for interzonal airflow estimation in naturally ventilated buildings. The presented method is based on the continuous measurements of CO2 concentration at one point in each zone. These measurements are used to estimate airflow pattern in a multizone building by applying an inverse analysis. The developed methodology employs an iterative Levenberg-Marquardt procedure to maximise the nonlinear likelihood function. The validity of the method was verified against measurements carried out in a single naturally ventilated room. Further, the method was applied to calculate the airflow pattern in two apartments in Poland, containing 4 and 6 zones. The obtained results revealed very poor ventilation in both investigated apartments and reversed airflow in exhaust ducts. The amount of fresh air entering the rooms was insufficient to ensure good indoor air quality. The developed methodology can be effectively used as a diagnostic tool to identify the potential problems with ventilation systems. [ABSTRACT FROM AUTHOR]

The article presents the results of measurements of temperature, relative humidity and CO2 concentration in six single-family houses' bedrooms located in Poland, in Wrocław and vicinity, during two climatic seasons: summer–autumn and winter. Two buildings with natural ventilation (NV) were tested, three with mechanical ventilation with heat recovery (MV) and one with hybrid ventilation (HV)—mixed mode natural and mechanical. The behavior of residents regarding opening windows was analyzed and the influence of the changing internal and external conditions on their active reactions was examined. The analysis confirms and adds to the global discourse on the key impact of user behavior on securing healthy indoor air quality in housing, regardless of ventilation system or building energy standard. A disconnect exists between the observed window opening practices and typical design principles, assuming adjustment to a given ventilation system or changing weather conditions. The observations showed that in both analyzed seasons it was possible to obtain a good quality internal environment, in terms of CO2 level, regardless of the ventilation system used in the building. However, unfavorable results were observed for one bedroom, in which the inhabitants do not adapt their behavior to local technical conditions. Taking into account the level of relative humidity (RH), much higher values were observed in the NV bedrooms in both analyzed periods. The obtained results were divided into IAQ classes in accordance with the EN 16798-1. The recorded values of the internal temperature confirm the significant influence of the location of the room in the building and the actions taken by the residents. [ABSTRACT FROM AUTHOR]

In recent years, the indoor air quality (IAQ) of educational buildings has attracted people's attention. As a resting place, the dormitory occupies more than half of the students' time in school. During sleep, the IAQ in dormitories is easily affected by breathing, which in turn affects the sleep quality and mental state of students. In order to study the relevant IAQ during sleep, this paper selected the dormitories of graduate students of different grades in a university in northern China, and monitored the temperature, humidity, CO2, PM2.5, HCHO and TVOC for two weeks during the changing seasons of autumn and winter. In addition, by issuing questionnaires, students made a subjective evaluation of the IAQ. According to the results of objective monitoring data and subjective evaluation, the IAQ changes in student dormitories of different grades, genders, and locations are statistically analyzed, and the correlation between environmental parameters is discussed. The research results show that temperature and humidity basically meet the national standards; indoor PM2.5 is positively correlated with outdoor PM2.5; and HCHO and TVOC are positively correlated with indoor temperature and humidity. Most dormitories lack natural ventilation, and the concentration of CO2 during sleep is too high, which affects the quality of sleep and mental state. [ABSTRACT FROM AUTHOR]

Indoor PM2.5 in apartments must be effectively managed to minimize adverse impacts on human health. Cooking is the one of the main PM2.5 sources in apartments, and indoor air quality (IAQ) management methods (natural ventilation, mechanical ventilations, range hoods, and air purifiers) are typically used to reduce PM2.5 generated during cooking. For effective control of indoor PM2.5, prediction of PM2.5 reduction for various IAQ management methods is necessary. This study carefully predicted indoor PM2.5 concentrations in an apartment when IAQ management methods were applied separately and/or in combination during cooking. The infiltration and exfiltration were verified by comparing the experimental results of CO2 concentration with those predicted with or without mechanical ventilation. The deposition rate for PM2.5 generated by cooking was also derived by comparing the experimental PM2.5 changes with the predicted values for PM2.5 natural decay. Through this method, effective PM2.5 control ways during cooking in apartments can be proposed, such as natural ventilation with a range hood for 30 min and then the operation of an air purifier for 30 min. Additionally, if this prediction is combined with energy consumption, it will be possible to propose the most energy‐efficient indoor PM2.5 control methods for various seasons and outdoor conditions. [ABSTRACT FROM AUTHOR]

People spend much of their lives indoors, so air quality is particularly important to their health, ability to work, and well-being. The COVID -19 pandemic has heightened people's awareness of the importance of maintaining high indoor air quality. Such an emergency has underscored the need for adequate heating, ventilation and air conditioning systems that can provide a good indoor air quality, especially ventilation systems as important players in preventing and reducing the risk of airborne infections. In this paper, we review natural and mechanical ventilation and their roles in dealing with coronavirus, focusing on key factors for healthy indoor air. Two pillars are critical for ventilation: increased air exchange rate and air filtration in ventilation systems. [ABSTRACT FROM AUTHOR]

Over centuries different elements have been developed in architectures for ensuring adequate natural ventilation in residential units. This study assesses the different components of an ancient windmill in Sistan, Iran, on the structure's indoor air quality (IAQ) enhancement. Several climatic scenarios have been defined by the wind analysis of Sistan meteorological data and analyzed by CFD. The site measurements confirm the accuracy of the simulation results. In the windmill, two deflectors facing the prevailing wind are the significant elements which, in addition to directing wind toward the entrance, could form vortices near the east and west openings leading to suction ventilation. Alteration of the wind speed and angle from 10 to 15 m/s and 30° to 17° would increase the air change per hour (ACH) by 150% and 110%, respectively. Meanwhile, the ACHs were higher than the ASHRAE desired level (ACH > 0.35). [ABSTRACT FROM AUTHOR]

Thermal comfort affects not only the well-being of the occupants of a building but also the effectiveness of their learning and work efficiency. It can be disturbed if the ventilation airflow is increased when improving indoor air quality. When natural ventilation is used in the fall and winter period, the supply air temperature is low, resulting in a lack of thermal comfort. In existing buildings, there is often no place for mechanical ventilation; hence, decentralised façade ventilation units are increasingly used. The article presents an analysis of thermal comfort in rooms with this type of unit equipped with heat recovery exchangers of different efficiencies. Studies have shown that the alternating supply/exhaust airflow and the related unevenness of air streams flowing through the heat accumulator cause an inflow of low-temperature air, resulting in thermal discomfort. The highest value of the PMV index was −1.6, and the lowest was −4.1, which means that 54.8 to 100% of the occupants are dissatisfied with their thermal comfort. This means there is a need to change the construction of inlet/exhaust vents so that the stream of supply air is not directly parallel to the floor. In addition, the use of an air heater should be considered. [ABSTRACT FROM AUTHOR]

This document provides updates on the activities of various Special Interest Groups (SIGs) related to air quality and climate change. The SIGs are seeking input and participation from members and can facilitate the sharing of information and events such as webinars. The document includes reports from different SIGs, including the Air Quality and Health SIG, the Biomass Smoke SIG, the Indoor Air SIG, the Measurement SIG, the Modelling SIG, the Emerging Air Quality Professionals SIG, the Odour SIG, the Transport SIG, and the Climate Change SIG. Each SIG report highlights the activities and discussions within the respective group. [Extracted from the article]

Indoor air quality (IAQ) is a significant concern for occupant comfort, productivity levels, health, and well-being. The presence of harmful chemicals, inhalable particles, and toxic materials can be ten times worse as compared to outdoor air pollution. The increased concentration of PM10 pollutants in the indoor environment is a serious threat to human health in terms of critical respiratory health issues. Literature supports the application of artificial intelligence for the prediction of pollutant concentrations in building environments. In this paper, we proposed a novel application of fuzzy inference system (FIS) optimized using particle swarm optimization (PSO) and genetic algorithm (GA) for forecasting PM10 concentration. The study was conducted on experimental data obtained from an Internet of Things-based IAQ monitoring system. The real-time monitoring system measures four indoor air pollutants: PM10, PM2.5, CO2, and VOC, along with two crucial thermal comfort parameters (Temperature and Humidity). The forecasting performance of the FIS with normalized dataset was measured in terms of MSE = 4.3656; MAE = 1.9351; MAPE = 9.633% and RMSE = 2.0894. Two optimization algorithms have improved RMSE FIS-PSO = 1.0746; and FIS-GA = 0.998. The optimized FIS can be used to develop real-time air quality prediction systems for indoor environments to promote health and well-being for building occupants. [ABSTRACT FROM AUTHOR]

This cross-sectional study investigated the indoor air quality (IAQ) of public health centers (PHCs) and primary health care units in Bangkok to determine the impact of the different locations and ventilation systems concerning IAQ. Three indoor air pollutants: PM2.5,CO2, and CO were measured in three areas (medical record departments, outpatient departments and examination rooms) of six PHCs located in two different locations (main and secondary roadsides). The results showed that the average levels of PM2.5, CO2, and CO in the PHCs located on main roadsides were higher than those located on secondary roadsides. Among these parameters, only CO was found to significantly differ between those two locations indicating the result of vehicles and traffic sources regarding indoor CO level. Furthermore, all parameters were compared among the sampling areas with different ventilation systems; natural ventilation and air conditioner with and without ventilation fan. The amounts of all three pollutants significantly differed in each area with different ventilation systems. The average levels of PM2.5 and CO2 were the highest in areas with air conditioner without ventilation fan, while the level of CO was the highest in areas with natural ventilation. The ventilation was proved to be a key measure to improve IAQ. PHCs should consider ventilation efficacy to improve the IAQ by using ventilation fans in rooms using air conditioners. Finally, the average levels of all parameters were found below the recommended values in related standards, indicating safe IAQ for people working and receiving services in PHCs. [ABSTRACT FROM AUTHOR]

Aerosol pollutant particles indoors significantly affect public health. The conventional wisdom is that natural ventilation will alleviate the dispersion of airborne or aerosol particles. However, we show that the problem is far more complex and that natural ventilation should be applied under specific conditions to be effective. We performed several simulations of a simplified (and easily reproducible) room with a window opening and aerosol particles stratified layers. Opening a window can scatter particles present in stratified layers indoors and potentially contribute to the degradation of indoor air quality for a significant period of time. Moreover, we show that thermal instabilities arising from the temperature gradients due to temperature differences between the indoor and outdoor environment spread the particles randomly indoors, adversely affecting air quality and architectural design. Recommendations for more efficient natural ventilation minimizing aerosol pollutant particles dispersed indoors are provided. [ABSTRACT FROM AUTHOR]

Digitalization offers new, unprecedented possibilities to increase the energy efficiency and improve the indoor conditions in buildings in a cost-efficient way. Smart buildings are seen by many stakeholders as the way forward. Smart buildings feature advanced monitoring and control systems that allow a better control of the buildings' indoor spaces, but it is becoming evident that the massive amount of data produced in smart buildings is rarely used. This work presents a long-term evaluation of a smart building testbed for one year; the building features state-of-the-art monitoring capability and local energy generation (PV). The analysis shows room for improving energy efficiency and indoor comfort due to non-optimal control settings; for instance, average indoor temperatures in all winter months were above 24 °C. The analysis of electricity and domestic hot water use has shown a relevant spread in average use, with single users consuming approximately four times more than the average users. The combination of CO2 and temperature sensor was sufficient to pinpoint the anomalous operation of windows in wintertime, which has an impact on energy use for space heating. Although the quantification of the impact of users on the overall energy performance of the building was beyond the scope of this paper, this study showcases that modern commercial monitoring systems for buildings have the potential to identify anomalies. The evidence collected in the paper suggests that this data could be used to promote energy-efficient behaviors among building occupants and shows that cost-effective actions could be carried out if data generated by the monitoring and control systems were used more extensively. [ABSTRACT FROM AUTHOR]

This paper proposes a novel optimal control method for multi-zone HVAC systems to enhance energy efficiency and improve occupant comfort. To address the disturbances in outdoor weather and indoor loads, the proposed method formulates the HVAC control problem as a dynamic Markov decision process, and employs deep reinforcement learning (DRL) techniques to obtain the optimal control policy. To manage multiple goals among thermal comfort, indoor air quality (IAQ) and system energy efficiency, a preference-inspired (P-ins) mechanism is designed to achieve the optimal balance among different objectives. The P-ins mechanism effectively guides the agent towards the optimal control policy with high convergence rate. The proposed method has been validated through EnergyPlus-Python co-simulation testbed with real-world data traces, and assessed by an overall evaluation indicator. Results demonstrate that the proposed method can reduce energy consumption without compromising thermal comfort and IAQ. Specifically, the occurrence of temperature violations is reduced below 0.8 %, and a maximum energy saving of 9.41 % can be achieved, compared with traditional methods. • The proposed method reduces HVAC energy consumption and improves occupant comfort. • A P-ins mechanism is devised to achieve optimal balance among all objectives. • An EnergyPlus-Python co-simulation test bed is built for validation. • The energy consumption is reduced by 9.41 % compared with rule-based methods. • The proposed method is robust and applicable to various test scenarios. [ABSTRACT FROM AUTHOR]

This article presents measurements of air quality in school and kindergarten facilities, which were carried out in 311 spaces throughout the Republic of Slovenia, before taking measures to improve energy efficiency of measured buildings. During the measurements, the internal dimensions of the spaces were also measured, as well as data on the energy efficiency of buildings and weather data at the time of the measurements. The measurements focused on indoor carbon dioxide concentration levels and air temperature and relative humidity of indoor air. The performed statistical analysis of measurements shows a large dispersion of measured parameters in buildings, which cannot be statistically significantly related to the analyzed quantities. During the occupancy of the spaces, a statistically significant difference in the concentration of carbon dioxide in the indoor air between the spaces of schools and kindergartens was found. The results of the measurements were also evaluated from the point of view of the Corona virus disease (COVID-19) pandemic. The average value of measured carbon dioxide value during occupancy of the spaces was compared with the results of a model that predicts an airborne transmission risk. The measured average value of relative humidity in kindergartens shows that relative humidity was 37 %, where is the highest infection risk according to recent studies. The measured average carbon dioxide concentration in classrooms and playrooms significantly exceeds the safe concentration, predicted by the model, to prevent COVID-19 spread at the expected six-hour exposure. [ABSTRACT FROM AUTHOR]

[Display omitted] Indoor air quality (IAQ) has assumed new significance given the extensive amount of time spent indoor due to the coronavirus pandemic and particulate matter (PM) pollution. Accordingly, the development of window air filters to effectively intercept PM from outdoor air under natural ventilation conditions is an important research topic. However, most existing filters inevitably suffer from the compromise among filtration capability, transparency, and air permeability. In this study, we fabricate a high-performance transparent air filter to improve IAQ via natural ventilation. polyvinylidene fluoride (PVDF) superfine nanofibers of size 20–35 nm are prepared using extremely dilute solution electrospinning; a multi-scale nanofiber structure is then designed. By adjusting the ratio of PVDF superfine nanofibers (SNs) to PVDF coarse fibers (CNs), we balance the structure–performance relationship. Benefiting from the multiscale structural features that include a small pore size (0.72 μm) and high porosity (92.22%), the resulting filters exhibit excellent performance including high interception efficiency (99.92%) for PM 0.3 , low air resistance (69 Pa), high transparency (∼80%) and stable filtration after 100 h of UV irradiation. This work describes a new strategy for the fabrication of nanofibers with true-nanoscale diameters and the design of high-performance air filters. [ABSTRACT FROM AUTHOR]

Natural ventilation has become one of the most effective and sustainable strategies to address COVID-19 in confined spaces. Air intake through windows and other openings improves the Indoor Air Quality (IAQ) of a classroom, decreases the likelihood of respiratory disease transmission with an adequate social distance of about 1.5 m and is affordable in terms of energy consumption. In this study, a comparison of CO2 concentration, wind speed, number of people, type of ventilation and window surfaces of a school in a Mediterranean climate is carried out for 4 different cases of opening. For this purpose, CO2 levels were measured in different classrooms with different window openings (33%, 67%, 81% and 100% respectively). In addition, three types of ventilation (cross ventilation, partial cross ventilation and multidirectional ventilation) were analyzed in a time period between February and March 2021. The results show an interaction between CO2 levels and the type of ventilation. Thus, the fact that the window surface is a critical factor in reducing CO2 concentrations was determined, considering that the distance between students was approximately 1.5 m. Therefore, the orientation of buildings towards the predominant wind direction and the Window to Floor Ratio (WFR) should be reconsidered in new constructions. [ABSTRACT FROM AUTHOR]

Reasonable air distribution is crucial to improve the air quality in hospital consulting room. Different air distribution schemes have certain effects on indoor temperature field, air flow field and particle concentration field. Based on a large general hospital project, this paper makes a subjective questionnaire survey and field test on indoor air quality of hospital buildings. Field test parameters include temperature, indoor air velocity, humidity, carbon dioxide and total volatile organic compound concentration. The results of the questionnaire survey show that a small number of people are not satisfied with the air quality in the hospital consulting room, and the concentration of carbon dioxide in some areas is high, which affects human health. The geometric model is established according to the test data, and the numerical simulation is carried out by CFD software to study the effects of three different air distribution. The research results show that the air distribution form of up-supply and side-return is more suitable for hospital consulting room and the air quality is better. [ABSTRACT FROM AUTHOR]

Windcatcher natural ventilation is a low-energy approach that can provide effective ventilation during favourable weather conditions. When combined with different cooling, heating, and dehumidification technologies, windcatchers can provide enhanced indoor environment quality. This work provides a critical review of windcatchers' performance. It covers aspects such as ventilation, thermal comfort, overheating risk, indoor air quality (IAQ), energy performance, economic cost, and life cycle assessment (LCA). Although many studies have investigated windcatchers' performance in terms of thermal comfort, little attention has been paid to the potential overheating risk. This oversight is particularly important in the context of global warming trends and the increasing likelihood of extreme weather conditions. Moreover, previous studies on windcatchers' IAQ performance have primarily focused on indoor CO 2 concentrations, while the influences of pollutants such as volatile organic compounds (VOCs) have not been reported. The quantification of energy performance for windcatchers remains an underexplored area, and very few studies have conducted economic analyses or LCAs of windcatcher systems. There is a clear need for more field experiments to investigate these aspects comprehensively. This review also provides insights into the current trends and future perspectives in the commercial windcatcher market, including available options, opportunities, and threats. The findings highlight the importance of several factors that must be considered before the large-scale commercial rollout of windcatcher technology. These include the lack of awareness and regulatory incentives, cost considerations, aesthetic preferences, and misconceptions or concerns regarding the effectiveness of windcatchers. [Display omitted] • Low-energy cooling, heating and dehumidification integrations are discussed. • The energy performance and overheating risk are rarely addressed. • There is a lack of research on the economic cost and life cycle assessment. • Challenges of commercialisation and widespread adoption are assessed. • Current and future trends in the market, opportunities and challenges are reviewed. [ABSTRACT FROM AUTHOR]

The global COVID-19 pandemic has highlighted the importance of indoor air quality and ventilation to mitigate the spread of respiratory viral infections. Schools, in particular, represent a vulnerable environment with high occupancy rates, prolonged exposure times and often inadequately ventilated rooms. This paper evaluates the functionality of different natural and retrofitted mechanical ventilation strategies in this context. An experimental setup, combining empirical measurements with building performance simulation and analytical risk analysis was used to assess key performance characteristics, including the energetic performance, thermal comfort, indoor air quality and the airborne infection risk of SARS-CoV-2. The results of this study underscore the need for a holistic approach to ventilation design in schools, taking into consideration the balance between energy performance, carbon emissions, thermal comfort, indoor air quality and associated health factors. We demonstrate that the risk of one or more long-range airborne infections, with the SARS-CoV-2 Omicron variant, can be reduced by >50% through appropriate use of natural, mechanical or hybrid ventilation in a classroom setting. Analytical modelling demonstrates that this risk can be further reduced, by an order of magnitude, through the use of FFP2 masks. • 5 classroom ventilation strategies were evaluated using measured and modelled data. • Mechanical and hybrid ventilation were compared to natural ventilation strategies. • Energy, thermal comfort, IAQ and SARS-CoV-2 infection risk criteria were evaluated. • None of the ventilation scenarios could eliminate the risk of aerosol transmission. • Hybrid systems provide the best compromise solution for all criteria. [ABSTRACT FROM AUTHOR]

Children spend a large part of their growing years in schools, and as they are more sensitive to some pollutants than adults, it is essential to monitor and maximize the indoor air quality (IAQ) in classrooms. Many schools are located in historic and heritage buildings, and improving the IAQ, preserving the architectural features, poses a great challenge. The aim of the study is to evaluate the effectiveness of a low-invasiveness, low-cost, smart CO2-based visual alerting systems to manage natural ventilation and improve IAQ in historic school buildings. Indoor and outdoor parameters were monitored for three weeks in four schools with different levels of education (two classrooms per school; device installed in one only). Based on indoor CO2 concentration, air temperature and relative humidity, the device suggests when windows should be opened to ventilate. The comparison between the two classrooms show that the effectiveness of the device is highly dependent on the occupants: (i) reduction in the average CO2 concentrations of up to 42% in classrooms with frontal lesson and full occupancy, (ii) the device is not the most ideal solution for kindergarten due to the young age of the pupils, and (iii) it is more used during mild outdoor temperatures. [ABSTRACT FROM AUTHOR]