Indoor Air Quality In Buildings Research Articles

Spatial distribution of CO2 Impact on the indoor air quality of classrooms within a University

Indoor air quality (IAQ) remains a public and global concern. While CO2 does not pose health risks to occupants, high CO2 levels indicate insufficient ventilation, potentially accumulating pollutant concentrations. In buildings, occupants are identified as the main source of indoor carbon dioxide (CO2) through exhalation. Standard classrooms may have occupant density between 1.8 and 2.4m2/person. Therefore, the IAQ of classrooms and lecture theatres remain a concern. This study investigated airflow and contaminant (using CO2 as a proxy) distribution in two classrooms modelled using CFX a Computational Fluid Dynamics (CFD) software, verified against experimental measurements. The model provides the visualization of flow patterns so that the effects of external and internal flow fields in the classroom can be studied. The results show that there are large differences in classroom indoor ventilation performance due to the effects of wind direction and wind speed on building surface wind pressure from outdoor wind speeds. Windward high-pressure surfaces and leeward vortices created by building shading promote indoor air quality in buildings with windcatcher openings. The concentration distribution of CO in the classrooms showed an upward convergence with the thermal plume generated by the respiratory differences of the personnel and the temperature of the lighting equipment. The results of this study have important implications for improving classroom design guidelines for school buildings, especially in terms of ventilation strategies and air quality monitoring.

A new clustering method with an ensemble of weighted distance metrics to discover daily patterns of indoor air quality

This paper presents a novel clustering method with an ensemble distance metric to identify meaningful daily patterns of building indoor air quality (IAQ). The novelty of this work is to construct an ensemble of weighted distance metrics with weights being adaptive to the characteristics of IAQ data. The ensemble distance was constructed based on Euclidean distance, Pearson correlation coefficient and cross-correlation coefficient to capture absolute levels, overall trends, and volatilities of IAQ data. The weights for individual distance metrics are automatically adapted to the characteristics of IAQ data based on the Z-scores of the distances among all pair-wise samples in the dataset. In addition, IAQ daily time series are segmented into short sequences to reduce the computational cost. Two datasets containing one-week IAQ observations were used to verify the proposed method. The results showed that the proposed method is able to capture insightful information on the distribution and frequency of the peaks, volatilities, and absolute levels of various IAQ parameters by identifying the patterns with unique characteristics from the IAQ daily sequences. The use of the ensemble distance metric offered better performance with an improved pattern consistency rate of 11–22% when compared with using a single distance metric for IAQ data. The discovered patterns can provide an increased understanding of the pollutant levels, the IAQ changing trends, and the distributions in the peaks and valleys of IAQ pollutants and, hence, can support the optimal operation of building HVAC systems.

Estimation of Natural Ventilation Rates in an Office Room with 145 mm-Diameter Circular Openings Using the Occupant-Generated Tracer-Gas Method

Natural ventilation in a building is an effective way to achieve acceptable indoor air quality. Ventilation dilutes contaminants such as bioeffluents generated by occupants, substances emitted from building materials, and the water vapor generated by occupants’ activities. In a building that requires heating and cooling, adequate ventilation is crucial to minimize energy consumption while maintaining healthy indoor air quality. However, measuring the actual magnitude of the natural ventilation rate, including infiltration through the building envelope and airflow through the building openings, is not always feasible. Although international and national standards suggested the required ventilation rates to maintain acceptable indoor air quality in buildings, they did not offer action plans to achieve or evaluate those design ventilation rates in buildings in use. In this study, the occupant-generated carbon dioxide (CO2) tracer gas decay method was applied to estimate the ventilation rates in an office room in Seoul, South Korea, from summer to winter. Using the method, real-time ventilation rates can be calculated by monitoring indoor and outdoor CO2 concentrations without injecting a tracer gas. For natural ventilation in the test room, 145 mm-diameter circular openings on the fixed glass were used. As a result, first, the indoor CO2 concentrations were used as an indicator to evaluate how much the indoor air quality deteriorated when all the windows were closed in an occupied office room compared to the international standards for indoor air quality. Moreover, we found out that the estimated ventilation rates varied depending on various environmental conditions, even with the same openings for natural ventilation. Considering the indoor and outdoor temperature differences and outdoor wind speeds as the main factors influencing the ventilation rates, we analyzed how they affected the ventilation rates in the different seasons of South Korea. When the wind speeds were calm, less than 2 m/s, the temperature difference played as a factor that influenced the estimated ventilation rates. On the other hand, when the temperature differences were low, less than 3 °C, the wind speed was the primary factor. This study raises awareness about the risk of poor indoor air quality in office rooms that could lead to health problems or unpleasant working environments. This study presents an example of estimating the ventilation rates in an existing building. By using the presented method, the ventilation rate in an existing building can be simply estimated while using the building as usual, and appropriate ventilation strategies for the building can be determined to maintain the desired indoor air quality.

A Review of Portable Air Cleaner Devices: Purification Processes, Performance Standards, and Effectiveness in Controlling Indoor Air Pollutants

Background and Objective: Indoor air pollutants are among the five most important environmental health risks. In recent years, concerns regarding indoor air quality in buildings have increased. This review has investigated studies conducted on portable air cleaners. Materials and Methods: After determining the keywords, conducting comprehensive searches in the internet databases, and taking into account the inclusion and exclusion criteria, a complete review was conducted to obtain the latest findings and the general trend of the studies. Results: Portable air cleaner devices are very diverse and are divided based on the type of technology used. Many standards have been developed to evaluate the performance of these devices in different countries, but none of them cover all aspects of performance. The effectiveness of these devices in removing VOCs is between 20% and 80%, depending on the type of technology and other influencing factors, and their effectiveness in removing suspended particles is between 70% and 95% on average. Furthermore, their efficiency in controlling COVID-19 is reported to be above 80% in cases where HEPA filters with grades 13 and above are used. Conclusion: Devices equipped with the HEPA filtration process have been found to be very effective in controlling indoor suspended particles. The use of devices equipped with UVGI, plasma, and ozone technologies should be accompanied by caution due to dangerous by-products.

Mechanical, natural and hybrid ventilation systems in different building types: Energy and indoor air quality analysis

Ventilation is fundamental for providing good Indoor Air Quality in buildings. Nevertheless, it involves considerable energy consumption. In this paper, a co-simulation approach was applied to two case studies, a residential and an educational building, to evaluate different control strategies for hybrid ventilation systems in terms of annual energy demand and risk mitigation. The simulations were performed using TRNSYS and CONTAM and successively applying the Wells-Riley model to estimate the airborne infection risk. The analysis is performed for three climates, Venice, Rome and Helsinki. Results for the apartment show that different control strategies do not lead to significant variations in the overall heating demand for a given climate. In contrast, increasing natural ventilation hours during the cooling season produces savings in both sensible (up to 31% in Venice) and latent demand (up to 30% in Rome). Fan absorption in the heating season is reduced by 40% and 86% in Rome for the flat and classroom, respectively and by 84% in Venice for the apartment in the cooling season. Moreover, a control strategy enhancing natural ventilation is promising in reducing the infection risk. Therefore, if well-regulated through a suitable control strategy, the hybrid ventilation system seems promising in maintaining healthy indoor environments while reducing energy consumption.

New ventilation design criteria for energy sustainability and indoor air quality in a post Covid-19 scenario

The Covid-19 outbreak raised great attention to the importance of indoor air quality in buildings. Even if the Covid-19 epidemic is nearing an end, all stakeholders agree that increasing outside air flow rates is beneficial for decreasing the likelihood of contagion, lowering the risk of future pandemics, and enhancing the general safety of the interior environment. Indeed, diverse concerns raised about whether the ventilation standards in place are still adequate. In this context, this research intends to assess the suitability of current ventilation standards in addressing the current pandemic scenario and to offer novel criteria and guidelines for the design and operation of HVAC systems, as well as useful guidance for the creation of future ventilation standards in a post-Covid-19 scenario. To that end, a comprehensive analysis of the ANSI/ASHRAE 62.1 is carried out, with an emphasis on its effectiveness in reducing the risk of infection. Furthermore, the efficacy of various ventilation strategies in reducing the likelihood of contagion has been investigated. Finally, because building ventilation is inextricably linked to energy consumption, the energy and economic implications of the proposed enhancements have been assessed. To carry out the described analysis, a novel method was developed that combines Building Energy Modelling (BEM) and virus contagion risk assessment. The analyses conducted produced interesting insights and criteria for ventilation system design and operation, as well as recommendations for the development of future standards.

The influence of ventilation on indoor air quality in buildings with variable pollutant emissions

Indoor Air Quality (IAQ) assurance is done mainly through the air exchange between interior and exterior. Lack of adequate ventilation of indoor spaces causes poor air quality and a higher incidence of sick building syndrome (SBS), which is manifested by affecting the comfort and wellbeing in the indoor spaces. Ensuring high energy performance buildings and indoor air quality is efficiently approached by limiting emissions from sources, by partial neutralization of the pollutants or by smarter ventilation. The concept of smart ventilation was developed to ventilate properly while reducing energy loads, allow for the provision of grid services, and promote associated renewable power integration. The above-mentioned information can be obtained by the air quality modelling, using mathematical approaches to predict the way pollutants behave in a certain environment or time scale. The paper presents the results obtained by mathematical modelling of indoor air quality, by including the transfer of pollutants from external sources and variable indoor emissions. The considered pollutants are ozone (O3), particulate matter (PM2.5), formaldehyde (HCHO) and carbon dioxide (CO2), due to the significant adverse effects on human health and their different preponderantly sources: indoor, outdoor or both indoor and outdoor. The main goal of our researches is the reducing of the amount of energy that ventilation uses while maintaining or improving IAQ.

Effects of Indoor Environmental Quality in Urban Housing on Residents' Health and Wellbeing in Nigeria

The building industry's contribution as a non-clinical contributor to the quality of life is its impact on occupants' health. A health-based standardised questionnaire and a digital data collection device were used to investigate the susceptibility of building indoor air quality (IAQ) to infectious diseases. PM2.5 (63 μm/m3) and PM10 (228 μm/m3) obtained exceeded the international standard. Some associations between certain building characteristics and potential risk factors for certain diseases were seen. This study provides a platform for future intervention in housing and public health policies and addresses the conundrum of safe and healthy buildings for the urban populace in Nigeria

기존 주택용 창문 부착형 현열교환 환기장치 제안 및 성능 평가

Purpose: Air pollution is becoming serious around the world, and indoor air quality in buildings is also deteriorating. For energy-saving ventilation and good indoor air environment, this research proposed and made a window type heat exchange ventilation system that can be installed easily in an existing house, and examined its performance. A plate type heat exchange element for ventilator was made by a 3D printer. Method: According to the Korean Industrial Standard KS B 6879:2020 Test Method for Heat Recovery Ventilator, the ventilator was tested four times in a real environment. Two experiments were measured for 10 minutes, and the remaining two were measured for 11 hours and 10 hours, respectively. Ventilation, supply air, exhaust air, and outside air dry-bulb temperatures were measured every 5 seconds. After that, the temperature exchange efficiency was calculated for ventilation, supply air, exhaust air, and outside air average temperature using the temperature exchange efficiency formula described in KS B 6879:2020. Result: The performance was 70.97% in the first experiment, 68.11% in the second experiment, 56.47% in the third experiment, and 64.16% in the fourth experiment.

Evaluating the effects of indoor air quality on teacher performance using artificial neural network

PurposeA building's Indoor Air Quality (IAQ) has a direct impact on the health and productivity on its occupants. Understanding the effects of IAQ in educational buildings is essential in both the design and construction phases for decision-makers. The purpose of this paper is to outline the impact air quality has on occupants' performance, especially teachers and students in educational settings.Design/methodology/approachThis study aims to evaluate the effects of IAQ on teachers' performances and to deliver air quality requirements to building information modelling-led school projects. The methodology of the research approach used a quasi-experiment through questionnaire surveys and physical measurements of indoor air parameters to associate correlation and deduction. A technical college building in Saudi Arabia was used for the case study. The study developed an artificial neural network (ANN) model to define and predict relationships between teachers' performance and IAQ.FindingsThis paper contains a detailed investigation into the impact of IAQ via direct parameters (relative humidity, ventilation rates and carbon dioxide) on teacher performance. Research findings indicated an optimal relative humidity with 65%, ranging between 650 to 750 ppm of CO2, and 0.4 m/s ventilation rate. This ratio is considered optimum for both comfort and performanceOriginality/valueThis paper focuses on teacher performance in Saudi Arabia and used ANN to define and predict the relationship between performance and IAQ. There are few studies that focus on teacher performance in Saudi Arabia and very few that use ANN in data analysis.

Empirical modelling of filtration performance for the fibrous air filters with final resistance recommendation

A significant challenge in the filtration applications is the high energy consumption across the air filters, especially with the dust cake formation after a certain period of usage. Therefore, the design of the air filters is important to maintain a good filtration performance with low energy consumption. An accurate setpoint of the final resistance acts as a reference of filter replacement, ensuring the energy-saving of the system and the indoor air quality (IAQ). In the industrial practice, the final resistance is set according to ASHRAE 52.2's recommendation or using the Rule of Thumbs as there is a lack of related literature studies. In this study, a pleated fiberglass air filter is studied to identify the factors affecting filtration performance and formulate the final resistance relationship. The filtration performance parameters, including the initial pressure drop, filtration efficiency, pressure drop across the dust cake and the dust holding capacity of the filter, are studied experimentally. The empirical models of filtration performance parameters are expressed in terms of different contributing factors. The validated empirical models are used for the prediction in the final resistance model in consideration of the filter lifespan and energy cost. The final resistance model developed is FinalResistance=ΔP0ⅇQηTtFRCupDHClnΔPfΔPi where tFR is determined in consideration of the filter's predicted lifespan and energy cost. The proposed filtration performance and final resistance models can provide a reference in giving a better design solution while maintaining the building's IAQ at minimized operation cost.

Comparative study of purifications technologies and their application to HVAC systems

Nowadays, there is a growing demand to guarantee indoor air quality in buildings. This study presents a solution that combines hygrothermal control and purification of the air supplied to occupied spaces, in which the control and purification system is integrated into the air distribution ductwork. Among all the air purification technologies, not all of them are suitable to be used in the residential and tertiary sector along with already installed HVAC systems. In this study, a review of the state of the art of technologies is made and the major purification techniques are analysed and compared, i.e., negative ionization, ozone, ultraviolet light, photocatalytic oxidation, and high-efficiency filtration. The comparison is focused on key aspects such as the use with occupation, whether there is a biocide or not, whether it can be used with HVAC units, costs, and maintenance. Finally, an effective and viable purification solution for HVAC systems is presented. It consists of a compact device based on the ionization technology. An ionizer device is placed in the air in-take of ducted HVAC units that is capable of remotely controlling the main operating parameters of the HVAC equipment (switching on and off, operating mode, fan speed, and setpoint temperature) while reducing the suspension time of fine particles in the air. Various studies carried out in Airzone laboratories have empirically shown that the use of this device results in a 47% reduction in the maximum concentration of particulate matter of 2.5 µm or PM2.5 and up to a 55% reduction of the time these particles are suspended in the air.

Using Weather and Schedule Based Pattern Matching and Feature Based Principal Component Analysis for Whole Building Fault Detection—Part II Field Evaluation

Abstract In a heating, ventilation, and air conditioning (HVAC) system, a whole building fault (WBF) refers to a fault that occurs in one component but may trigger additional faults/abnormalities on different components or subsystems resulting in significant impacts on the energy consumption or indoor air quality in buildings. At the whole building level, interval data collected from various components/subsystems can be used to detect WBFs. In the Part I of this study, a novel data-driven method which includes weather and schedule-based pattern matching (WPM) procedure and a feature based principal component analysis (FPCA) procedure was developed to detect the WBF. This article is the second of a two-part study of the development of the whole building fault detection method. In the Part II of the study (this paper), various WBFs were designed and imposed in the HVAC system of a campus building. Data from both imposed fault and naturally occurred faults were collected through the building automation system (BAS) to evaluate the developed fault detection method. Evaluation results show that the developed WPM-FPCA method reaches a satisfactory detection rate (85% and 100% under two principal component retention rates) and a 0% false alarm rate (under two principal component retention rates).

Internet of Things (IoT) Technologies for Managing Indoor Radon Risk Exposure: Applications, Opportunities, and Future Challenges

Radon gas is a harmful pollutant with a well-documented adverse influence on public health. In poorly ventilated environments, that are often prone to significant radon levels, studies indicate a known relationship between human radon exposure and lung cancer. Recent technology advances, notably on the Internet of Things (IoT) ecosystem, allow the integration of sensors, computing, and communication capabilities into low-cost and small-scale devices that can be used for implementing specific cyber-physical systems (CPS) for online and real-time radon management. These technologies are crucial for improving the overall building indoor air quality (IAQ), contributing toward the so-called cognitive buildings, where human-based control is tending to decline, and building management systems (BMS) are focused on balancing critical factors, such as energy efficiency, human radon exposure management, and user experience, to achieve a more transparent and harmonious integration between technology and the built environment. This work surveys recent IoT technologies for indoor radon exposure management (monitoring, assessment and mitigation), and discusses its main challenges and opportunities, by focusing on methods, techniques, and technologies to answer the following questions: (i) What technologies have been recently in use for radon exposure management; (ii) how they operate; (iii) what type of radon detection mechanisms do they use; and (iv) what type of system architectures, components, and communication technologies have been used to assist the referred technologies. This contribution is relevant to pave the way for designing more intelligent and sustainable systems that rely on IoT and Information and Communications Technology (ICT), to achieve an optimal balance between these two critical factors: human radon exposure management and building energy efficiency.

The role of bio-pollutants in the indoor air quality of old museum buildings: artworks biodeterioration as preview of human diseases.

Indoor air quality in buildings is strongly affected by chemical, physical, and biological agents. Long exposure to inadequate indoor air quality can be very dangerous for the building occupants and can lead to chronic diseases associated with the sick building syndrome (SBS). In this paper, the large presence of biological pollutants in the indoor rooms of an old building and its strict relationship with the outdoor/indoor air conditions were investigated studying Coronini Cronberg Palace Foundation, a historic house museum of the sixteenth century in Gorizia (Italy), where biological contamination affecting the artworks can soon become potentially harmful also for operators and visitors. Detailed aerobiological and microbiological analyses on organic natural materials, combined with a microclimate monitoring, were conducted to evaluate the influence of temperature and relative humidity levels within the Palace in the conspicuous growth and diffusion of microorganisms. Fungal and bacterial colonies damaging materials, mainly affected by the sudden fluctuations of hygrothermal values, were found to widely exceed Italian and international recommended levels for good air quality for both artworks and human beings. Understand their impact on human health would be strictly necessary to reduce biological risks for museum staff and cultural heritage users, but consequently to improve indoor air quality.

Indoor Air Quality in Buildings: A Comprehensive Review on the Factors Influencing Air Pollution in Residential and Commercial Structure.

Worldwide people tend to spend approximately 90% of their time in different indoor environments. Along with the penetration of outside air pollutants, contaminants are produced in indoor environments due to different activities such as heating, cooling, cooking, and emissions from building products and the materials used. As people spend most of their lives in indoor environments, this has a significant influence on human health and productivity. Despite the two decades of indoor air quality (IAQ) research from different perspectives, there is still a lack of comprehensive evaluation of peer-reviewed IAQ studies that specifically covers the relationship between the internal characteristics of different types of building environments with IAQ to help understand the progress and limitations of IAQ research worldwide. Therefore, this review of scientific studies presents a broad spectrum of pollutants identified in both residential and commercial indoor environments, highlighting the trends and gaps in IAQ research. Moreover, analysis of literature data enabled us to assess the different IAQs in buildings located in different countries/regions, thus reflecting the current global scientific understanding of IAQ. This review has the potential to benefit building professionals by establishing indoor air regulations that account for all indoor contaminant sources to create healthy and sustainable building environments.

Contribution of compressed stabilized earth bricks (CSEB) to the control of indoor air quality in buildings: case study ofAlgeria

Contribution of compressed stabilized earth bricks (CSEB) to the control of indoor air quality in buildings: case study ofAlgeria

Analysis of the opportunities for improving energy efficiency in public buildings

Reducing energy consumption and maintaining an appropriate indoor air quality in buildings is a global trend. This is achieved in several ways – improving the building envelope thermal characteristics; fuel base replacement; introduction of smart energy consumption tracking systems. The aim of this paper is an analysis of the impact of energy efficiency measures introduced in buildings that provide health services. Measures have been taken to improve the energy performance of the envelope, as well as to modernize the system for the production and distribution of thermal energy. One complete year after energy savings measures implemented the total energy savings of 37.9% have been achieved. Further economic assessment has been made regarding the profitability of the applied measures.

Comparison of winter air infiltration and its influences between large-space and normal-space buildings

Air infiltration brings challenges to energy saving and indoor air quality in buildings. Previous studies about air infiltration mainly focused on normal-space buildings, while less attention has been paid to large-space buildings, which are currently widespread. This study uses theoretical models to compare winter air infiltration in the two categories of buildings. The most common situation of winter air infiltration in normal-space buildings is the outdoor air through envelope cracks; however, that in large-space buildings is actually some unintentional openings (i.e., normally-opened windows/skylights, exterior doors for entrance, etc.). The calculation results indicate no noticeable difference in the air change rate of winter air infiltration between the two categories of buildings, which is also supported by field measurement data from the literature. Then, this paper discusses the different challenges faced by the two categories of buildings with the influence of air infiltration. A smaller shape coefficient of a large-space building (0.07–0.27 m-1) results in a higher proportion of heating load by air infiltration than that of a normal-space building (0.20–0.80 m-1). Besides, a smaller occupant number per volume of indoor space of a large-space building (1.6 × 10−4 to 1.2 × 10−2 person/m3) makes it less likely to be severely affected by indoor-originated air pollutants (indicated by CO2 concentration) than that of a normal-space building (1.3 × 10−2 to 2.1 × 10−1 person/m3).

New and innovative wind catcher designs to improve indoor air quality in buildings

Wind catchers used in various countries in Middle East and North Africa in order to improve indoor air environment and to reduce reliance on cooling load. However, nowadays they are used across the globe with modern shapes and advanced techniques. The study focuses on investigating new and innovative shapes of wind catchers to improve air speed indoors which will elevate indoor comfort and air quality in buildings. The study used computer modeling CFD and a real model experiment to conduct the study. The study highlighted that curved shapes have highest pattern of wind speed driven, especially curved shape with double inlets. In addition, the study showed that octagon shape has the lowest pattern of wind speed driven because of its various sides which prevent air to flow easily inside the tunnel.