Indoor Air Quality Conditions Research Articles

Soundscape and indoor air quality in naturally ventilated educational environments: a multi-domain study

In this study, indoor air quality (IAQ) and acoustics were jointly analysed to determine their i) combined effect on students' performance in a math task, and ii) cross-modal effect on soundscape perception. 192 students (12 to 14 years) took part in a laboratory experiment. Students were separated into two classroom-like chambers with different IAQ conditions: a CO2 concentration of 800 and 2000 ppm, respectively. The participants were asked to solve calculations and answer a soundscape questionnaire in three listening conditions: quiet, a natural scenario with birdsongs, and one scenario with children's playground activity sounds. In the latter two conditions, the sounds were played back through headphones at a level of 47 dBA. Results show that students had faster response times in the math task in quiet compared to the listening condition with children's activity sounds, while maintaining a similar task accuracy. No effect of the IAQ conditions and natural sounds was found on the task performance. No cross-modal effect of CO2 concentration on soundscape perception was detected. Regarding soundscape assessments, playground activity was rated as the most annoying listening condition, while listening to birdsongs was the most pleasant one, despite its noise level exceeding the quiet condition.

Comparison of cooking emissions mitigation between automated and manually operated air quality interventions in one-bedroom apartments

We implemented a crossover study design exposing 15 participants to two indoor air quality conditions in the Well Living Lab. The first condition, the Standard Control Condition, resembled the ventilation and air supply of a typical home in the USA with a manually operated stove hood. The second condition, Advanced Control, had an automated: (i) stove hood, (ii) two portable air cleaners (PAC), and (iii) bathroom exhaust. The PM2.5 sensors were placed in the kitchen, living room, bedroom, and bathroom. Once the sensor detected a PM2.5 level of 15 μg/m3 or higher, an air quality intervention (stove hood, PAC or bathroom exhaust) in that space was activated and turned off when the corresponding PM2.5 sensor had three consecutive readings below 6 μg/m3. Advanced Control in the overall apartment reduced PM2.5 concentration by 40% compared to the Standard Control. The PM2.5 concentration difference between Advanced and Standard Control was ~ 20% in the kitchen. This can be attributed to using the stove hood manually in 66.5% of cooking PM2.5 emission events for 323.6 h compared to 88 h stove hood used in automated mode alongside 61.9 h and 33.7 h of PAC use in living room and bedroom, respectively.

Association of Perceived Thermal Comfort and Air Quality with Building- and Occupant-Related Characteristics and Environmental Parameters in Sweden

The aim of the article is to analyze the perceived thermal comfort and indoor air quality of occupants and establish associations between these responses and the building-related, occupant-related characteristics, and environmental parameters of residential buildings (a total of 38 variables). The analysis is focused on the Swedish building stock as investigated during the latest national survey in 2008. The analysis covers 1035 residential buildings (multifamily and single-family dwellings). Analytical statistical analysis has been conducted, and logistic regression models have also been developed for the identification of statistically significant covariates. The analysis showed that users in this study demonstrated a significantly positive response to perceived thermal comfort and indoor air quality conditions. Perceived ratings were also highly correlated with each other. As the regression models indicated, the majority of the significant variables were related to the buildings. Nevertheless, this study also underscores the significance of contextual occupant attributes and behaviors as a crucial element influencing the subjective perception of indoor environments. Policymakers, guided by these insights, are encouraged to integrate considerations of occupant attributes into design and urban planning.

Monitoring of Ventilation, Portable Air Cleaner Operation, and Particulate Matter in California Classrooms: A Pilot Study

Interest in improving ventilation and indoor air quality (IAQ) in California schools has grown since the COVID-19 pandemic. This paper presents a field protocol for simultaneous monitoring of usage patterns of in-room portable air cleaners (PACs), indoor and outdoor concentrations and composition of particulate matter (PM), and CO2 as an indicator of outdoor air ventilation rates (VRs). This protocol was implemented for a 7-week pilot study in four occupied California classrooms in 2022. Monitoring results showed that VRs and indoor PM were generally well maintained in the classrooms studied. One classroom had much higher overall VRs, as well as higher average indoor PM2.5 concentrations compared to similar classrooms, suggesting a possible strong impact of window/door opening behavior on both VRs and indoor PM. The actual use patterns of PACs in these classrooms varied significantly. No clear correlations were observed between PAC use patterns and indoor PM2.5 concentrations in this pilot study, possibly due to low outdoor PM2.5 concentrations and already efficient central filtration (i.e., MERV 13 filters in central ventilation systems). Information gathered through such field monitoring can help schools to understand the actual classroom ventilation and IAQ conditions and best allocate resources to classrooms that need further IAQ improvements.

Economic viability of under floor heating system: a case study in Beirut climate

This paper explores the economic feasibility of the underfloor heating system for the climatic conditions of Beirut. A case study of a typical residential room (150 m2 ) is selected to compare its heating energy requirement when using either the conventional convective heating system or the underfloor heating system at similar comfort and indoor air quality conditions. Two mathematical models are developed, a steady space thermal model to establish the energy consumption at the peak load and a transient simulation model to find the energy consumption during the winter heating season. In addition, the economic feasibility of the underfloor heating system is assesd when integrated with solar energy. Based on the steady space model, the calculated peak heating load is reduced by 20% when the test space is heated by the underfloor heating system and a thermal comfort level of PPD 18.3% is achieved for a floor temperature of 27.4 ºC. The simulation results of the transient space model indicates that the seasonal heating energy consumption is reduced by 18% and that the yearly energy savings is $104 for an on-off control strategy that maintains a PMV comfort level greater than -0.5. The pay back period of the underfloor heating system is 10 years for an initial incremental cost of $850. When integrated with 10 solar collector units, the yearly energy savings of the integrated system is increased to $350 and the pay back period is 14 years.

Concentration of Indoor Air Chemical Parameters at Different Ship Conditions and Engine Sequences

Good indoor air quality (IAQ) is crucial for navy crew due to longer periods onboard, especially during pandemic. Increased frequency of the ship’s operations is required to prevent trespassing and illegal border crossings. This study aims to determine and compare the indoor air chemical parameters; carbon dioxide (CO₂), carbon monoxide (CO), and total volatile organic compounds (TVOC) at different ship conditions (alongside and sailing) and engine sequences (idling, cruising, full ahead and slowing down). The parameters were measured in four compartments, following the Industry Code of Practice on Indoor Air Quality 2010 (ICOP IAQ 2010). At different ship conditions, there were significant differences of indoor air chemical parameters in the common room, electrical room, and accommodation area 2. However, no trend of higher or lower concentrations was observed between the conditions due to ship operation, human activities, and occupancy. The engine sequences affect the indoor air chemical parameters, where the CO concentrations were recorded higher in all compartments, especially when the engine was running at 1000 rpm. In conclusion, the navy crew could be exposed to unacceptable IAQ conditions regardless of ship conditions and engine sequences. It is good to highlight that good ventilation is crucial to dilute the air pollutants onboard.

Evaluation of the impact of ventilation system daily operation on air quality, comfort and well-being in primary schools

The Scol’air-FR project is issued from the need to establish an inventory of indoor air quality conditions in primary schools of the canton of Fribourg, Switzerland. In Fribourg, the official trend is to promote mechanical ventilation systems in schools to ensure a good air quality. A properly designed, built, commissioned, and operated mechanical ventilation system should be able to deliver the anticipated flow rate, regardless of who uses it - the only person involved being the person responsible for ventilation system operation. In some cases, however, the expected objectives are not achieved. This similar observation applies to natural ventilation. A good ventilation concept, properly implemented and operated, should also achieve the same objective if the outdoor air quality is good. The aim of this article is to identify differences, in terms of indoor air quality and well-being, between naturally and mechanically ventilated schools. Moreover, we expect to identify if trends are attributable to the operation of ventilation systems or to occupant behaviours. We observed lower carbonic gas levels in building equipped with mechanical ventilation systems. This finding can be extended to VOCs and relative humidity. We also identified different and recurrent issues among the different mechanical ventilation systems. Our results highlight issues measured in buildings equipped by mechanical ventilation systems are mostly related to the balance of the system, while in natural ventilation systems, IAQ related issues are mainly due to the present context and its influences on occupants’ behaviour.

Retracted: Deep learning-based energy inefficiency detection in the smart buildings

The operation of the heating, ventilation, and air conditioning (HVAC) system is essential for the indoor thermal environment and is significant for energy consumers in commercial properties. Although earlier studies suggested that reinforcement learning controls could increase HVAC energy savings, they lacked sufficient details regarding end-to-end management. Recently, the focus on gathering and analyzing data from smart meters and buildings connected to energy-saving studies has increased. Deep reinforcement learning (DRL) suggests novel methods for operating HVAC systems and lowering energy usage. This paper evaluates energy consumption by Convolution Recurrent Neural Networks (CRNN), and Deep Reinforcement Learning is used. This is intended to forecast energy use under various climatic circumstances, and the processes are assessed under different communication protocols. The suggested control technique might directly accept quantitative elements, such as climate and indoor air quality conditions, as input and control indoor thermal set - points at a supervisory level by utilizing the deep neural network. In a highly effective office area in the Houston area, time series data, CRNN, and DRL are effectively used to uncover new energy-saving options (TX, USA). The article presents 1-year information from the Net Zero, Energy Star, and Leadership in Energy and Environment Design (LEED)-certified building, demonstrating a potential energy savings of 8% with the presented design. The findings demonstrate how useful the suggested strategy is in assisting building owners in locating new potential for energy conservation.

Understanding how indoor environmental classroom conditions influence academic performance in higher education

PurposeThis study aims to qualitatively examine the relationship between the indoor environmental quality (IEQ), lecturers’ and students’ perceived internal responses and academic performance.Design/methodology/approachTo capture user experiences with the IEQ in classrooms, semi-structured interviews with 11 lecturers and three focus group discussions with 24 students were conducted, transcribed, coded and analyzed using direct content analysis.FindingsThe findings show that lecturers and students experience poor thermal, lighting, acoustic and indoor air quality (IAQ) conditions that may influence their ability to teach and learn. Maintaining acceptable thermal and IAQ conditions was difficult for lecturers, as opening windows or doors caused noise disturbances. In uncomfortable conditions, lecturers may decide to give a break earlier or shorten a lecture. When students experienced discomfort, it may affect their ability to concentrate, their emotional status and their quality of learning.Research limitations/implicationsThe findings originate from a relatively small sample, which might have limited the number and variety of identified associations between environment and users.Practical implicationsMaintaining acceptable air and thermal conditions will mitigate the need to open windows and doors. Keeping doors and windows closed will prevent noise disturbances and related distractions. This will support the quality of learning in classrooms. This study reveals the end users’ perspectives and preferences, which can inspire designers of new school buildings in higher education.Originality/valueThis study emphasizes the importance of creating and maintaining optimal IEQ conditions to support the quality of teaching and learning. These conditions are particularly relevant when classroom occupancy rates are high or outdoor conditions are unfavourable.

6 Comparison of Ammonia Concentrations Between Flush and Pull-Plug Waste Management Systems in Wean-Finish Swine Barns

Abstract Pig manure contains a wide variety of corrosion-inducing chemicals such as ammonia. Ammonia production and its release are influenced by temperature and moisture in the barn environment. Increased concentrations of ammonia can negatively affect pig health and growth, as well as pose a risk to human health. Additionally, even at decreased concentrations, ammonia reacts with humidity and causes premature corrosion of barn equipment and is a threat to the structural integrity of livestock buildings. In this study, ammonia concentrations were monitored and compared between two 880 head wean-finish swine facilities with different types of waste management systems. Both facilities had shallow manure pits, one containing a flush system and one containing a pull plug system to remove manure from the barns into the lagoon. Ammonia, dry-bulb air temperature, and relative humidity levels were measured every0 min for an entire wean-finish cycle (approximately 20 weeks). Data will be compared between the facilities to evaluate the impact of the waste management systems on indoor air quality conditions. Potential implications for pig health and growth and facility maintenance will be explored. Results will provide information on best management strategies for swine facilities.

Crosscutting of the pollutants and building ventilation systems: a literature review.

Considering the time spent in enclosed environments, it is essential to study the relationship between pollutants and building ventilation systems to find whether the types and levels of pollutants and greenhouse gasses, which are expected to be exhaled through ventilation systems into the atmosphere, have been adequately evaluated. We propose the hypothesis that the exhaled air from residential buildings contains pollutants that may become another source of contamination affecting urban air quality and potentially contributing to climate drivers. Thus, the main goal of this article is to present a cross-review of the identification of pollutants expected to be exhaled through ventilation systems in residential buildings. This approach has created the concept of "exhalation of buildings" a new concept enclosed within the research project in which this article is included. We analyze the studies related to the most significant pollutants found in buildings and the studies about the relation of buildings' ventilation systems with such pollutants. Our results show that, on the one hand, the increase in the use of mechanical ventilation systems in residential buildings has beendemonstrated to enhance the ventilation rate and generally improve the indoor air quality conditions. But no knowledge could be extracted about the corresponding environmental cost of this improvement, as no systematic data were found about the total mass of contaminants exhaled by those ventilation systems. At the same time, no projects were found that showed a quantitative study on exhalation from buildings, contrary to the existence of studies on pollutants in indoor air.

Indoor environmental quality in offices and risk of health and productivity complaints at work: A literature review

Many service jobs are carried out in modern offices, with individual offices being increasingly replaced by open-plan settings. The high number of adult people working in office buildings, in most situations sharing the workplace with many others during a considerable part of their daily time, highlights the importance of providing adequate guidance to ensure the quality of office environments. This paper aims to summarize existing data on modern offices' indoor environmental quality (IEQ) conditions in terms of air pollution (volatile organic compounds (VOC), particulate matter and inorganic pollutants), thermal comfort, lighting and acoustics and the respective associations with health and productivity-related outcomes in workers. Evidence shows that although many offices present acceptable IEQ, some office settings can have levels of air pollutants, hygrothermal conditions/thermal comfort and illuminance that do not comply with the existing international standards and recommendations. In addition, findings suggest the existence of significant associations between the assessed IEQ indicators and the risk of detrimental effects on health and productivity of office workers. In particular, airborne particles, CO2, O3 and thermal comfort were linked with the prevalence of sick building syndrome symptoms. Poor lighting and acoustical quality have also been associated with malaise and physiological stress among office workers. Similarly, better productivity levels have been registered for good indoor air quality conditions, in terms of VOC, airborne particles and CO2. Overall, the evidence revised in this work suggests that for promoting health and productivity recommendations for office building managers include actions to ensure that: i) all relevant IEQ indicators are periodically controlled to ensure that levels comply with recommended limit values; ii) declared indoor pollution sources are avoided; iii) adequate ventilation and acclimatization strategies are implemented; and iv) there is the possibility of conduct personalized adjustments to environmental conditions (following workers' preferences).

Analysis of Symptoms of Sick Building Syndrome for Nurses in Hospital Inpatient Rooms

Sick Building syndrome is a symptom that is felt by someone who carries out activities in the building caused by poor indoor air quality conditions that can cause several symptoms of health problems. The purpose of this study was to analyze complaints of sick building syndrome among nurses in hospital inpatient rooms. This research method uses quantitative methods with analytic survey types. The design used was a cross-sectional study with a total sample of 120 people. Data analysis used the chi-square test. The results of this study showed that as many as 40% of nurses experienced symptoms of sick-building syndrome with the most common complaints being sneezing, runny nose/flu, dry skin, dry lips, and feeling tired. And the factors associated with the symptoms of sick building syndrome in nurses are temperature, humidity, lighting, occupancy density, air circulation, years of service, and age. So that hospital management needs to periodically check the physical environment in hospital inpatient rooms.

Positive effects of indoor environmental conditions on students and their performance in higher education classrooms: A between-groups experiment

This study explores if multiple alterations of the classrooms' indoor environmental conditions, which lead to environmental conditions meeting quality class A of Dutch guidelines, result in a positive effect on students' perceptions and performance. A field study, with a between-group experimental design, was conducted during the academic course in 2020–2021. First, the reverberation time (RT) was lowered in the intervention condition to 0.4 s (control condition 0.6 s). Next, the horizontal illuminance (HI) level was raised in the intervention condition to 750 lx (control condition 500 lx). Finally, the indoor air quality (IAQ) in both conditions was improved by increasing the ventilation rate, resulting in a reduction of carbon dioxide concentrations, as a proxy for IAQ, from ~1100 to <800 ppm. During seven campaigns, students' perceptions of indoor environmental quality, health, emotional status, cognitive performance, and quality of learning were measured at the end of each lecture using questionnaires. Furthermore, students' objective cognitive responses were measured with psychometric tests of neurobehavioural functions. Students' short-term academic performance was evaluated with a content-related test.From 201 students, 527 responses were collected. The results showed that the reduction of the RT positively influenced students' perceived cognitive performance. A reduced RT in combination with raised HI improved students' perceptions of the lighting environment, internal responses, and quality of learning. However, this experimental condition negatively influenced students' ability to solve problems, while students' content-related test scores were not influenced. This shows that although quality class A conditions for RT and HI improved students' perceptions, it did not influence their short-term academic performance.Furthermore, the benefits of reduced RT in combination with raised HI were not observed in improved IAQ conditions. Whether the sequential order of the experimental conditions is relevant in inducing these effects and/or whether improving two parameters is already beneficial, is unknown.

Modeling indoor PM2.5 using Adaptive Dynamic Fuzzy Inference System Tree (ADFIST) on Internet of Things-based sensor network data

Indoor air pollution is crucial for the building environment as it has a direct impact on human health, prosperity, comfort, and productivity levels. Repeated exposure to toxic materials and harmful chemicals leaves a considerable impact on occupant well-being. The degraded air quality in the indoor environment is closely connected to the rising cases of respiratory health issues, cardiovascular disease, lung cancer, and a wide spectrum of symptoms. Therefore, it is required to design a reliable system to assess indoor air quality (IAQ) in residential and commercial spaces to improve the health outcomes and productivity levels of the building occupants. The main contribution of this paper is to provide a rigorous design and development approach for the IAQ monitoring system using the Internet of Things-based sensor network. Furthermore, a forecasting model was designed using Adaptive Dynamic Fuzzy Inference System Tree to predict PM2.5 conditions in the target building environment. The performance of the proposed system is tested over multiple datasets obtained from different rural and urban locations; moreover, the findings are further validated against benchmark datasets. The updates about real-time IAQ conditions in the target building environment were made accessible to occupants via an online web portal, and the entire system was named “Vayuveda” – an approach for enhanced air quality in the living spaces. The authors tested multiple methods at every step of the development process and compared performance at each stage to come out with the best model for real-time IAQ assessment.

Indoor Air Quality in the Uffizi Gallery of Florence: Sampling, Assessment and Improvement Strategies

The assessment of indoor air quality (IAQ) in museums is a complex issue. In this study, a comprehensive investigation methodology was defined and applied to a museum to be validated. This methodology includes the analysis of exposed objects, the optimal conditions for conservation, the building features and the HVAC systems, and the indoor thermo-hygrometric and air quality conditions. In 2019, a survey in the Uffizi Gallery of Florence, one of the most important museums in the world, was carried out to assess the IAQ conditions in the museum, and the workers and visitors’ well-being, by focusing on some representative rooms (nine) of the museum complex in terms of visitor turnout and HVAC systems, including rooms closed to the public. Since IAQ is related to the possible presence and concentration of chemical and biological pollutants, these indicators, as well as thermo-hygrometric parameters, were monitored. The monitoring results were analyzed, evaluated, and compared with those suggested by the literature, guidelines and legislative documents dealing with IAQ in museums. Monitoring approaches for deepening investigations, as well as guidelines aimed at improving IAQ in the Uffizi Gallery and similar buildings are proposed.

Design, fabrication, and calibration of the Building EnVironment and Occupancy (BEVO) Beacon: A rapidly-deployable and affordable indoor environmental quality monitor

Indoor Air Quality (IAQ) monitoring is essential to assess occupant exposure to the wide range of pollutants present in indoor environments. Accurate research-grade monitors are often used to monitor IAQ but the expense and logistics associated with these devices often limits the temporal and spatial scale of monitoring efforts. More affordable consumer-grade sensors – frequently referred to as low-cost sensors – can provide insight into IAQ conditions across greater scales but their accuracy and calibration requirements need further evaluation. In this paper, we present the Building EnVironment and Occupancy (BEVO) Beacon. The BEVO Beacon is entirely open-source, including the software, hardware, and design schematics which are all provided on GitHub. We created 20 of these standalone, stationary devices which measure up to 24 parameters at a one-minute resolution of which we focus on carbon dioxide, carbon monoxide, total volatile organic compounds, temperature, and size-resolved particulate matter. We investigated the efficacy of two different calibration approaches – device-specific and environment-averaged – for these sensors as well as also provide an extensive discussion considerations for each of the sensors. Calibrated sensors performed well when compared to reference monitors or calibrated gas standards. The CO sensors yielded the best agreement (r2=0.98-0.99), followed by temperature (r2=0.89-0.99), CO2 (r2=0.62-0.99), and PM2.5 (r2=-0.13-0.91). In all cases, the device-specific calibration approach yielded the most accurate results. We evaluated our devices through a successful 11-week field study where we monitored the IAQ in participants’ bedrooms. The work we present on consumer-grade sensors adds to the existing literature by considering sensor-specific calibration techniques and analysis. The BEVO Beacon adds to the successful line of similarly developed devices by providing an open-source framework that researchers can readily adapt and modify to their own applications.

Indoor Air and Light Quality Assessment in a University Campus Classroom

Educational buildings should provide a secure, healthy, and comfortable indoor environment for students since they spend a noteworthy part of their time inside. The present study aims to identify and assess the key indicators related to the light and air quality of a campus classroom, which contributes to the health of students. The indicators are chosen from an existing green rating tool, the WELL Building Standard (WBS). The research methodology consists of three main phases; indicator selection, impact assessment, and validation process. The engagement of stakeholders was taken into the account in the entire research framework. The research findings showed that there is a considerable gap among the acceptable range of indoor air and the light quality of the classroom. This led to verifying various health issues among the students, including dryness and irritation of the skin and eyes, and consequently increased their dissatisfaction rate. The study provides some significant insights based on the obtained results, highlighting the importance of incorporating student health and wellness into educational building design and operations, including visual comfort and indoor air quality conditions, which are often worse than the stipulations in standards.

Indoor air quality (IAQ) in a naval ship after refit program: a time variation analysis

Abstract Refurbishments of the ship’s external and internal structures are the main scopes of a refit program. These activities may affect the indoor air quality (IAQ) inside ships and increase the indoor air pollutants (IAP) concentrations onboard. Therefore, continuous IAQ monitoring is needed to determine IAP exposure to the ship’s crew. This study evaluates the changes in IAQ conditions inside a naval ship over a two-time interval to determine the effect of compliance with the recommended engineering control measures proposed in the first assessment. Following the standard of the Industry Code of Practice on Indoor Air Quality 2010 (ICOP on IAQ 2010), seven IAQ parameters (temperature, relative humidity (RH), carbon dioxide (CO2), respirable particulates/particulate matter (PM10), total volatile organic compounds (TVOC), bacterial count, and fungal count) were measured in two assessment phases. The first phase was conducted after the ship completed the refit program, and the second phase began three months later, following the execution of the recommended engineering control measures. According to the findings of this study, all IAQ parameters improved when compared to the first phase assessment. However, some of the readings were still non-compliance with the standards of ICOP on IAQ 2010. In conclusion, the ship’s IAQ parameters were improved following the recommended engineering control measures, although more enhanced approaches were required to ensure all parameters complied with the ICOP on IAQ 2010.

An effect of numerical data through monitoring device on perception of indoor air quality

Despite a growing interest in indoor air quality (IAQ), a scientific basis for human self-awareness and understanding of IAQ has yet to be provided. To fill this research gap, this study examined the effect of numerical data through monitoring devices on the occupants’ perception of IAQ. Therefore, an experiment was planned to evaluate the perceived IAQ based on a self-report questionnaire among ten subjects in an office environment. The experiment was divided into three sessions, with a classification model built for each session using automated machine learning and then derived variable importance for predictor variables. Results showed that when occupants did not check the numerical data of IAQ factors, they tended to perceive IAQ based on the perceived thermal comfort. In addition, occupants made a biased judgment of the current IAQ condition based on the past perceived IAQ checked 30 min ago. When occupants checked the numerical data of IAQ factors, they responded more sensitively to IAQ factors than to thermal environment factors when perceiving IAQ conditions. The results of this study confirmed that real-time numerical data of IAQ factors measured using monitoring devices are essential for occupants to perceive and judge the current IAQ clearly.