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Accelerated concrete carbonation is an expanding option for decarbonizing construction. Factors such as concrete mixture design and carbonation environment can influence the maximum CO2 utilization that can be achieved during such a process. A carbonation process designed to utilize a water‐saturated dilute CO2 source wherein 2 < CO2 concentration (v/v%) < 16, was modeled in AspenPlus©. A regression model was developed to correlate CO2 uptake, relative humidity (11%–100%), CO2 concentration ([CO2] = 2—16 v/v%), and temperature (T = 11–74°C) conditions within a carbonation reactor. It was determined that [CO2] was the most significant variable as higher concentrations enhanced CO2 transport through the concrete. The energy use intensity per mass of CO2 utilized (kWh/kgCO2) was determined across a range of processing conditions. As a function of the operational conditions, accelerated carbonation provides a net CO2 reduction of up to 28 kgCO2/tonne of concrete; a reduction of up to ~45% compared to typical formulations. [ABSTRACT FROM AUTHOR]

The impact of the COVID-19 pandemic has caused an increase in knowledge in certain fields such as human breathing and respiratory diseases. In the current study, enclosed-space characteristics were assessed due to the great debate generated because of the pandemic. Temperature, relative humidity, carbon dioxide (CO2) concentration, particulate matter (PM) concentration and cumulative particle concentration percentage per size fraction were measured in three buildings under the occurrence of activities with different intensity levels. For the measurements, Arduino UNO, Sensiron SCD30 and APS-3321 devices were used. Natural ventilation was controlled via windows and/or doors, and the influence of air conditioning was studied in one of these rooms, in which medium- to high-intensity activities were conducted. All experiments revealed a decrease in temperature associated with an increase in the relative humidity when CO2 decreased. As a consequence, drastic decreases occurred a few minutes after windows and doors were opened. In no-ventilation intervals, the observed linear increase changed into an asymptotic trend below the 1000 ppm limit recommended by Sinphonie guidelines. Additionally, the opposite behavior was observed between particles above and below a certain size. This experiment is of interest to further investigate critical ventilation rate versus volume of air per individual. [ABSTRACT FROM AUTHOR]

The population of developed nations spends a significant amount of time indoors, and the implications of poor indoor air quality (IAQ) on human health are substantial. Many premature deaths attributed to exposure to indoor air pollutants result from diseases exacerbated by poor indoor air. CO2, one of these pollutants, is the most prevalent and often serves as an indicator of IAQ. Indoor CO2 concentrations can be significantly higher than outdoor levels due to human respiration and activity. The primary objective of this research was to numerically investigate the indoor relative humidity and CO2 in cob buildings through the CobBauge prototype, particularly during the first months following the building delivery. Both in situ experimental studies and numerical predictions using an artificial neural network were conducted for this purpose. The study presented the use of a piecewise autoregressive exogenous model (PWARX) for indoor relative humidity (RH) and CO2 content in a building constructed with a double walling system consisting of cob and light earth. The model was validated using experimental data collected over a 27-day period, during which indoor RH and CO2 levels were measured alongside external conditions. The results indicate that the PWARX model accurately predicted RH levels and categorized them into distinct states based on moisture content within materials and external conditions. However, while the model accurately predicted indoor CO2 levels, it faced challenges in finely classifying them due to the complex interplay of factors influencing CO2 levels in indoor environments. [ABSTRACT FROM AUTHOR]

Knowledge of indoor air quality (IAQ) in cob buildings during the first few months following their delivery is of vital importance in preventing occupants' health problems. The present research focuses on evaluating IAQ in cob buildings through a prototype built in Normandy, France. To achieve this, the prototype was equipped with a set of sensors to monitor various parameters that determine indoor and outdoor air quality. These parameters include relative humidity (RH), carbon dioxide (CO2), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM1 and PM10), and volatile organic compounds (VOCs). The obtained experimental results indicate that, overall, there is good indoor air quality in the prototype building. However, there are some noteworthy findings, including high indoor RH and occasional spikes in CO2, PM1, PM10, and VOCs concentrations. The high RH is believed to be a result of the ongoing drying process of the cob walls, while the peaks in pollutants are likely to be attributed to human presence and the earthen floor deterioration. To ensure consistent good air quality, this study recommends the use of a properly sized Controlled Mechanical Ventilation system. Additionally, this study explored IAQ in the cob building from a numerical perspective. A Long Short-Term Memory (LSTM) model was developed and trained to predict pollutant concentrations inside the building. A validation test was conducted on the CO2 concentration data collected on-site, and the results indicated that the LSTM model has accurately predicted the evolution of CO2 concentration within the prototype building over an extended period. [ABSTRACT FROM AUTHOR]

In order to explore the indoor air quality during different cooking procedures, a very common kitchen in China is selected for experimental research. An indoor air quality meter is used to measure the temperature, relative humidity, and CO and CO2 concentrations of the indoor air above the stove when people cook four different dishes under different ventilation patterns in the kitchen. The results indicate that the heat and gas consumed during cooking are closely related to the temperature and concentrations of CO and CO2. Some cooking procedures such as boiling water are related to the indoor air temperature and relative humidity in the kitchen. In addition, in kitchens without mechanical ventilation, natural ventilation shows a more significant positive effect on controlling temperature, relative humidity, and concentrations of CO and CO2 during cooking procedures. [ABSTRACT FROM AUTHOR]

People spend most of their time in indoor environments without knowing about the air quality in these spaces. In this study, indoor low-cost sensors were used (for 5 months) to assess the comfort and air quality patterns in two indoor households. To strengthen the robustness of the considered approach and build confidence in the obtained comfort and indoor air quality (IAQ) levels, the sensor measurements were also compared against information from reference monitoring equipment; in which, high correlation coefficients were obtained (> 0.85) and also low errors (on average 22%). The IAQ results were strongly influenced by the residents' activity and behaviour, the outdoor weather conditions, and indoor/outdoor air pollution sources. Overall, the recommended values of temperature and relative humidity for the occupant's comfort in indoor environments were not fulfilled. The highest particulate matter (PM) levels were recorded at the weekend (on average +14% higher), while maximum CO2 and CO levels were obtained on the weekdays (on average +9% higher). PM daily profiles followed the outdoor concentrations with the maximum levels at the end of the night and the lowest values in the early morning/mid-afternoon. The highest and lowest CO2 concentrations were registered in the early morning (< 1536 ppm) and mid-afternoon (< 627 ppm), respectively, while the CO daily profiles showed a high impact of outdoor emissions, with the minimum concentrations up to 0.81 mg m−3 (at 10 a.m. or 6 p.m.), and a maximum concentration of 1.87 mg m−3 (at 10 p.m.). Real-time comfort conditions and IAQ levels are a powerful approach to providing fast decisions to minimise human exposure and prevent negative health impacts. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the characteristics of, exposure to, and factors influencing gas-phase and PM2.5-bound phthalates (PAEs) in nail salons. Data on both indoor and outdoor gas-phase and PM2.5-bound PAEs, carbon dioxide (CO2), temperature, and relative humidity were collected in nail salons. We also used questionnaires to survey building characteristics and occupants' behaviors. The average total gas-phase and PM2.5-bound PAE concentrations indoors were higher than those outdoors by 6 and 3 times, respectively. Diethyl phthalate, diisobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and di-(2-ethylhexyl) phthalate (DEHP) were the predominant compounds among both the gas-phase and PM2.5-bound PAEs in indoor air. The volume of the salon's space or the difference of indoor and outdoor CO2 concentrations (dCO2) was significantly associated with indoor PAE concentrations. The ratios of PM2.5-bound to gas-phase PAEs, especially high-molecular-weight PAEs, were positively associated with the dCO2 concentrations. Higher ratios of indoor to outdoor PM2.5-bound DiBP, DnBP, and DEHP concentrations were discovered when more clients visited each day. Building characteristics, ventilation conditions, and occupants' activities have influences on the gas-phase and particle-phase PAEs. The study identifies the characteristics of gas-phase and PM2.5-bound PAEs in nail salons and their influencing factors. [ABSTRACT FROM AUTHOR]

The amount of moisture in the air is represented by relative humidity (RH); an ideal level of humidity in the interior environment is between 40% and 60% at temperatures between 18° and 20° Celsius. When the RH falls below this level, the environment becomes dry, which can cause skin dryness, irritation, and discomfort at low temperatures. When the humidity level rises above 60%, a wet atmosphere develops, which encourages the growth of mold and mites. Asthma and allergy symptoms may occur as a result. Human health is harmed by excessive humidity or a lack thereof. Dehumidifiers can be used to provide an optimal level of humidity and a stable and pleasant atmosphere; certain models disinfect and purify the water, reducing the spread of bacteria. The design and implementation of a client-server indoor and outdoor air quality monitoring application are presented in this paper. The Netatmo station was used to acquire the data needed in the application. The client is an Android application that allows the user to monitor air quality over a period of their choosing. For a good monitoring process, the Netatmo modules were used to collect data from both environments (indoor: temperature (T), RH, carbon dioxide (CO2), atmospheric pressure (Pa), noise and outdoor: T and RH). The data is stored in a database, using MySQL. The Android application allows the user to view the evolution of the measured parameters in the form of graphs. Also, the paper presents a prediction model of RH using Azure Machine Learning Studio (Azure ML Studio). The model is evaluated using metrics: Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), Relative Absolute Error (RAE), Relative Squared Error (RSE) and Coefficient of Determination (CoD). [ABSTRACT FROM AUTHOR]

In their annual indoor air quality assessment for ADNOC Schools, the Abu Dhabi Education Council has reported hazardous levels (∼3000 ppm) of carbon dioxide in fifteen classrooms. Exposure of 5,090 students attending the school for ∼eight hours (typical school day) to such high levels of carbon dioxide would induce adverse health conditions like headaches, drowsiness, and lack of concentration on the short term and serious diseases like asthma and sick building syndrome on the long term. The Health, Safety, and Environment committee of the school has identified clogged air intake vents and dirty AC filters as the main cause of the high carbon dioxide concentrations reported. The outdoor (ambient) carbon dioxide level is measured and has an eight-hour average value of 419 ppm. After cleaning thoroughly, the indoor levels of carbon dioxide, temperature, and relative humidity were monitored simultaneously in each classroom and have average values of ∼1117 ppm, ∼24°C, and ∼37%, respectively. In addition, the average indoor-to-outdoor ratio of carbon dioxide has been improved from 3000 / 419 ≈ 7.2 before cleaning the AC filters to an average ratio of (1,117 / 419 ≈ 2.7) after cleaning. Thus, ventilation rates in the classrooms monitored in this project are adequate and the corrective actions taken were effective. [ABSTRACT FROM AUTHOR]

Indoor environmental conditions in intensive pig farms are influenced by both the outdoor air temperature and humidity, and the heat, moisture and gas exchanges between the animal and the air. As ventilation rate in pig facilities is usually estimated in temperature, moisture and even CO2 balances, estimation of heat losses or gains, and moisture and CO2 production from the animal is needed, but the contribution of other sources of the barn, such as slurry or wet surfaces have also to be taken into account. Some recent studies have been conducted to update total heat and moisture production at farm level, showing that current, historical standards of latent heat transfer are consistently lower than those reported recently at facility level, for both adult and growing animals. Also, CO2 production needs to be updated by including an estimation of its release from slurry. These new values will help with updating the standards for ventilation rate recommendations and design of the modern intensive pig buildings. [ABSTRACT FROM AUTHOR]

Highlights • CO 2 concentrations in classrooms with passive ventilation systems (PVHR) were satisfactory. • Airtightness significantly affects the performance of the passive ventilation system. • Passive ventilation system appears more sensitive to wind changes than to buoyancy. • Human behavior such as window opening can significantly boost the ventilation rate of the PVHR system. Abstract This paper presents the ventilation performance of a passive ventilation system with heat recovery (PVHR) based on in-situ monitoring in a primary school in London. The study involves long-term (15-month) monitoring of temperature, relative humidity and carbon dioxide (CO 2) concentrations in both the classrooms and the outdoor environment. In addition, short term (1- and 2-week) observational monitoring was performed in two classrooms at ventilation system level and classroom level, during both the heating and non-heating seasons. Temperatures and air velocities were measured within the PVHR system while instances of window opening and the number of students were noted in daily diaries. Air permeability and infiltration measurements were performed to characterize the spaces. Time-varying ventilation rates were estimated through a form of continuity equation considering CO 2 generation rates by occupants. Preliminary results show that the operation of the ventilation system is more sensitive to changes in wind speed and direction than to buoyancy. When negative pressure was observed on the classrooms' facades the ventilation system was supplying two to three times more air in comparison to instances when positive pressures were observed. The assessment of the ventilation performance of such natural ventilation systems depending solely on wind and buoyancy is complicated as they are dynamic systems that constantly balancing with the surrounding conditions, and the operation is highly correlated to the airtightness of the building's envelope. [ABSTRACT FROM AUTHOR]

Indoor air quality (IAQ) influences human health, productivity and wellness. Green buildings are believed to have better IAQ. The 'sick building syndrome' (SBS) describes a set of nonspecific symptoms experienced by occupants due to time spent in a building with poor IAQ. Thus this study was undertaken to assess the IAQ in green buildings and compare it with that of conventional buildings. The prevalence of SBS in both types of buildings is also studied. In five pairs of green and conventional buildings measurements of comfort parameters (temperature & relative humidity) and indoor air pollutants using monitors was done. 148 employees which included 84 from green buildings and 64 from conventional buildings were surveyed for SBS using an interviewer-administered questionnaire. The analysis was done using SPSS16 and included Mann Whitney for IAQ pollutant concentrations and Chi-square for the SBS prevalence. Similar indoor air quality was found in both types of buildings. The mean of temperature, CO2 and formaldehyde was statistically lower in green buildings. The SBS prevalence was found to be 38.1% in green buildings and 53.1% in conventional buildings. Thus to conclude the poorly maintained green building does not have any added advantage for occurrence of SBS. [ABSTRACT FROM AUTHOR]

Present study reports the characterization results of settled dust particles in different indoor micro-environments of an academic institution in India. Field emission scanning electron microscope analysis of indoor dust revealed the presence of mineral particles, fly ash, and soot particles of different morphologies. Energy-dispersive X-ray spectroscopy analysis of indoor dust indicated that crystal particles are comprised of elements such as C, O, Na, Mg, Al, Si, S, Cl, K, Ca, Fe, and Ti. These elements accounted for more than 99% of the samples. The average content of O (42.7%) and C (18.9%) in the dust particles was found to be higher than their natural abundances. The concentrations of PM10, PM2.5, and PM1 were observed in the range of 88-58, 37-33, 23-29 µg/m3, respectively. Except temperature, other parameters such as volatile organic carbon, carbon dioxide concentration, and relative humidity were found to be within comfort limits of American Society of Heating, Refrigerating, and Air-Conditioning Engineers. Abbreviations: ASHRAE: American Society of Heating, Refrigerating, and Air-Conditioning Engineers; CO2: carbon dioxide; COPD: chronic obstructive pulmonary disease; EDX: energy-dispersive X-ray; FESEM: field emission scanning electron microscope; FTIR: Fourier transform infrared spectroscopy; IAP: indoor air pollution; IAQ: indoor air quality; HAP: household air pollution; OAP: outdoor air pollution; PM: particulate matter; VOC: volatile organic carbon; WHO: World Health Organization [ABSTRACT FROM AUTHOR]

This study was carried out in order to determine the indoor air quality of the classrooms existing in university (Turkey). Relative humidity, temperature, carbon dioxide, radon, and particulate matters (PM0.5, PM1.0, PM2.5, PM5.0, and PM10) were taken into account as the parameters of indoor air quality measurements. The results obtained from the present work were interpreted by comparing them with the standards of different countries. The relations between all parameters were statistically examined by means of correlation and regression analysis in SPSS 17 statistical program. As a result, it was observed that indoor temperature was lower than the standards, yet carbon dioxide and PM values were higher than the upper limit, but relative humidity level was within comfort conditions. The average indoor radon concentrations were found to be below the recommended reference levels for International Commission on Radiological Protection (ICRP), yet it was seen that the results were relatively higher in comparison with the worldwide values. In addition, it was determined that there was a meaningful relation between outdoor relative humidity, indoor relative humidity, and particulate matters in different diameters. Some solutions were suggested for the treatment of the indoor air quality for each parameter. [ABSTRACT FROM AUTHOR]

The air conditioning applications in mosques are considered as one of the important HVAC applications, which indoor air quality depend on the behavior of the airflow, the distributions of temperatures and relative humidity and concentration of carbon dioxide due to high occupancy load of people. The paper is devoted to numerically investigate the influence of ventilation rate on indoor air quality. The example shown here is Al-Masa’a between Al-Safa and Al-Marwa hills inside Al-Haram mosque located at Makkah-Saudi Arabia. The work focuses on air flow, thermal behavior and carbon dioxide dispersion where large number of people. Five different cases for change in ACH are studied to reveal the impact of changing it on the all people. The performance of the air conditioning system is characterized by airflow patterns, temperature, relative humidity contours and CO2 concentration as well as the most commonly used comfort parameters PMV and PPD based on Fanger’s model. The study is carried out using computational fluid dynamics (CFD) simulation techniques as embedded in the commercially available CFD code (ANSYS 15). The CFD modeling techniques solved the continuity, momentum and energy conservation equations in addition to RNG k – ε model equations for turbulence closure. Mesh sizes used in present work exceeded 4.5 million approximately. [ABSTRACT FROM AUTHOR]

Indoor environmental conditions in classrooms, in particular temperature and indoor air quality, influence students' health, attitude and performance. In recent years, several studies regarding indoor environmental quality of classrooms were published and natural ventilation proved to have great potential, particularly in southern European climate. This research aimed to evaluate indoor environmental conditions in eight schools and to assess their improvement potential by simple natural ventilation strategies. Temperature, relative humidity and carbon dioxide concentration were measured in 32 classrooms. Ventilation performance of the classrooms was characterized using two techniques, first by fan pressurization measurements of the envelope airtightness and later by tracer gas measurements of the air change rate assuming different envelope conditions. A total of 110 tracer gas measurements were made and the results validated ventilation protocols that were tested afterward. The results of the ventilation protocol implementation were encouraging and, overall, a decrease on the CO concentration was observed without modifying the comfort conditions. Nevertheless, additional measurements must be performed for winter conditions. [ABSTRACT FROM AUTHOR]

Indoor air quality is a major part of indoor environmental quality and plays an important role in creating sustainable and healthy indoor environments. Well-being, health and comfort are affected by indoor air quality. The measurements that are introduced in this research paper were used to record the results of three different residential interiors. These data are a part of a larger scale research project that included the evaluation of residential buildings, offices, university interiors and for instance nurseries. The reason behind conducting the measurements in these interiors was that in all of the examples inadequate indoor air quality and therefore human discomfort, illness and also building failure occurred. In this paper the theoretical background of the research and the measurement of indoor air quality (indoor air temperature, relative humidity level and carbon dioxide level) will be introduced. The poor indoor air quality in these buildings is a result of a complex system. The thermal bridges of the facade cause cold interior surfaces, the airtight solutions cause high relative humidity levels. These two combined result in mould appearance. Besides, the lack of appropriate ventilation rate can be the third part of the reason behind poor indoor air quality. Based on the results of the measurement data, different solutions are suggested in each case to improve indoor environmental and air quality, in accordance with creating healthier indoor environments. [ABSTRACT FROM AUTHOR]

The paper presents the measurement results of actual microclimate conditions that were carried out in one of the Polish museums during the period of one year, from October 2009 to September 2010, under the two-year project on the optimization of microclimate in museum premises in case of variable outdoor and indoor loads. Recording environmental parameters (temperature and relative humidity) with a five-minute time step allowed the analysis of the dynamics of changes in these parameters due to variable thermal-hygrometric loads of the museum premises. Carbon dioxide concentration was also measured. The aim of the investigation was to identify these environmental parameters in different exhibition halls (both with and without air-conditioning systems) and comparing them with the limits suggested in literature and standards. Courses of variability allowed the observation of the rate of change of parameters recorded at different times of the year. The analyses of the results were conducted in terms of absolute values of air parameters in these premises and fluctuations of these parameters over time. Detailed analyses of the impact of outdoor conditions on the microclimate of museum rooms were performed. [ABSTRACT FROM AUTHOR]

A study of indoor environmental quality inside the old (naturally ventilated) and new (air-conditioned) train cabins and platforms of four main stations of the Athens subway system (Attiko Metro), took place in different two-day measurements from June to August 2012. Portable instrumentation provided continuous measurements of particulate matter (PM10, PM2.5 and PM1), carbon dioxide (CO2) along with temperature (T) and absolute humidity (AH). PM concentrations were significantly higher on the underground platforms of the network from 3 to 10 times, as compared to outdoor measurements. In particular, mean PM1, PM2.5 and PM10 concentrations at the deeper and most crowded station of Syntagma reached 18.7, 88.1 and 320.8 μg m-3 respectively. On the contrary, the ground level, open station of the Airport, showed values comparable to the outdoor (2, 6.4 and 34.4 μg m-3, respectively). All PM fractions were lower than the platforms inside the old and new train cabins while the air conditioned trains experienced lower particulate pollution levels. More specifically, mean PM1, PM2.5 and PM10 concentrations were 5.5, 16.8 and 58.3 μg m-3, respectively in new cabins while in the old they reached 10.3, 47.5 and 238.8 μg m-3. The PM2.5/PM10 and PM1/PM2.5 ratios did not exceed 0.33 on both platforms and trains verifying the dominance of crustal coarse particles originating from the train and ground materials. As expected CO2 levels were higher inside the trains as compared to the platforms and in some cases surpassed the 1000 ppm limit during the hottest days of the experimental campaign. Temperature and humidity remained relatively stable on the platforms, whereas measurements inside the cabins fluctuated, depending on the type of train and track locations. Correlations between measured PM along the routes to and from the Airport indicated covariance of concentrations along train cabins of the same direction. [ABSTRACT FROM AUTHOR]

Previous studies have shown that poorly ventilated classrooms can have negative impact on the health of children and school staff. In most cases, schools in Serbia are ventilated naturally. Considering their high occupancy, classroom air quality test determines the level of air pollution, after which it is possible to implement corrective measures. The research presented in this study, was conducted in four schools which are located in different areas and have different architecture designs. Measurements in these schools have been performed during the winter (heating season) and spring (non-heating season) and the following results were presented: indoor air temperature, relative humidity, and carbon dioxide concentration. These results show that the classroom average concentration of carbon dioxide often exceeds the value of 1500 ppm, during its full occupancy, which indicates inadequate ventilation. Measurement campaigns show that carbon dioxide concentration increased significantly from non-heating to heating season in three of the four schools. Analysis of measurements also determined high correlation between relative humidity and carbon dioxide concentration in all schools in winter season. This fact may constitute a solid basis for the fresh air supply strategy. [ABSTRACT FROM AUTHOR]

In this study, six poultry buildings, consisting of four layer hen houses and two broiler houses located in Manisa Province in Turkey, were examined to find out the effects of planning systems on indoor environmental conditions where the age of litter for broiler ranged from 4-18 weeks and the age of commercial layer hens ranged from 22-43 weeks. Air quality parameters, as concentrations of ammonia, carbon dioxide and methane were measured by using multi-gas monitor. Other parameters, as temperature/relative humidity and particulate matter were measured by using respectively psychrometric sensors and multi-function meter. These measurements were obtained as four replicates for each building in winter, early spring, and summer. The measured data were evaluated via repeated measures analysis of variance (rANOVA). According to the research results, measured indoor temperature values tend to rise in Californian cage type buildings in all seasons (max. 27.65 °C in winter and max. 41.85 °C in summer). The highest relative humidity values were measured in deep litter type buildings (max. 76.27% in winter and max. 80.44% in summer). Particulate matter levels had high values in Californian cage type buildings in summer (Avg. 1.09 mg/m3) and in deep litter type buildings in winter (Avg. 3.16 mg/m3). Concentrations of NH3 and CH4 had high levels in Californian cage type (34.68 ppm NH and 15.14 ppm CH4 max. values) and deep litter type (49.54 ppm NH3 and 19.32 ppm CH4 max. values) buildings in winter. NH3 and CH4 have a tendency to rise in all types of buildings in summer. CO2 had the highest levels in Californian cage type (max. 1805.57 ppm) and deep litter type (max. 8906.33 ppm) buildings in all seasons. Concentrations of CO2 had lower levels in summer than in winter in all types of poultry buildings. Statistical analysis showed that the design of poultry buildings determined indoor environmental conditions. Also, hot and humid local climate has the effects on indoor air quality. [ABSTRACT FROM AUTHOR]

Improved indoor air quality (IAQ) is one of the critical components of green building design. Green building tax credit (e.g., New York State Green Building Tax Credit (GBTC)) and certification programs (e.g., Leadership in Energy & Environmental Design (LEED)) require indoor air quality measures and compliance with allowable maximum concentrations of common indoor air pollutants. It is not yet entirely clear whether compliance with these programs results in improved IAQ and ultimately human health. As a case in point, annual indoor air quality measurements were conducted in a residential green high-rise building for five consecutive years by an industrial hygiene contractor to comply with the building's GBTC requirements. The implementation of green design measures resulted in better IAQ compared to data in references of conventional homes for some parameters, but could not be confirmed for others. Relative humidity and carbon dioxide were satisfactory according to existing standards. Formaldehyde levels during four out of five years were below the most recent proposed exposure limits found in the literature. To some degree, particulate matter (PM) levels were lower than that in studies from conventional residential buildings. Concentrations of Volatile Organic Compounds (VOCs) with known permissible exposure limits were below levels known to cause chronic health effects, but their concentrations were inconclusive regarding cancer health effects due to relatively high detection limits. Although measured indoor air parameters met all IAQ maximum allowable concentrations in GBTC and applicable LEED requirements at the time of sampling, we argue that these measurements were not sufficient to assess IAQ comprehensively because more sensitive sampling/analytical methods for PM and VOCs are needed; in addition, there is a need for a formal process to ensure rigor and adequacy of sampling and analysis methods. Also, we suggest that a comprehensive IAQ assessment should include mixed mode thermal comfort models, semi-volatile organic compounds, assessment of new chemicals, and permissible exposure levels of many known indoor VOCs and bioaerosols. Plus, the relationship between energy consumption and IAQ, and tenant education on health effects of indoor pollutants and their sources may need more attention in IAQ investigations in green buildings. [ABSTRACT FROM AUTHOR]

The present paper concerns the results obtained in a human subject experimental study, regarding the predefined occupant behavior with respect to aerating activities of a naturally ventilated space. During the experiment, various scenarios were investigated of different occupant's behavior patterns with regard to the degree of window opening. Indoor air temperature, relative humidity and CO2 volume fraction, were continuously measured and recorded. CO2 concentration time variation records were analyzed separately and the time change of this parameter was considered as a main indicator to distinguish the periods of infiltration only and the periods of conscious aeration activities, performed by the occupants. The developed evaluation procedures as well as the key results from the analyses are discussed in the paper. [ABSTRACT FROM AUTHOR]

Considering that air conditioning is widely applied for improving human standard of living, this present investigation is focused on the optimization of indoor air quality characteristics of air-conditioned cars using the Gray relational analysis (GRA) and the response surface methodology (RSM). The air-conditioned space is selected and the experiments are planned as per experimental design to study the effects of human load, fresh air supply, and air velocity on human comfort conditions. Mathematical models are developed to predict the comfort conditions, namely temperature, CO level, and relative humidity over a specified range of input conditions. The optimum values of comfort conditions for varying input conditions are found by assigning weightages to individual responses using GRA and RSM. [ABSTRACT FROM AUTHOR]

The present investigation was focused on the analysis of indoor air quality characteristics of an air conditioned car using statistical approach. The conditioned space was selected and the experiments were planned as per design of experiments to study the effect of human load, fresh air supply and air velocity on the human comfort conditions. The nonlinear regression models were developed to predict the comfort conditions namely temperature, CO2 level and relative humidity over a specified range of input conditions in this investigation. [ABSTRACT FROM AUTHOR]

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This study aims to investigate if a relationship can be established between measured indoor conditions and student performance in classroom settings. Ten classrooms in five Victorian schools in Australia were selected to monitor indoor conditions and measure student attention and concentration performance using a neuropsychological assessment, d2 Test of Attention. Correlation analysis revealed that the student performance parameters, particularly TN (reaction time, speed) and CP (accuracy), established a low to moderate correlation with most of the indoor condition parameters except CO 2 concentration level. An exploratory stepwise multiple regression analysis identified that the common predictors of TN are relative humidity (RH), mean radiant temperature (MRT) and PM 2.5 and the common predictors of CP are MRT and PM 2.5. Interestingly, relative humidity (RH) and CO 2 concentration level are the important predictors of both TN and CP among the seven environmental variables in the hierarchical multiple regression model when controlling the non-environmental variables such as student age and school terms. As thermal comfort related variables such as air temperature, air velocity and MRT were correlated with school terms due to seasonal changes, they contributed to the shared variance along with school terms in the regression model. Understanding the unique and shared contribution of the indoor condition parameters to student performance can help to develop strategies to improve school building performance. • Establishing the relationship between indoor conditions and student performance. • Common predictors of TN (reaction time, speed) and CP (accuracy) are MRT and PM 2.5 • RH and CO 2 are the important predictors when controlling age and school terms. • Understanding the contribution of the indoor conditions to student performance. [ABSTRACT FROM AUTHOR]

Abstract: The education process often begins in kindergarten. Because children spend there between 5 and 10h a day, the quality of air inside the building is of crucial importance. Kindergartens most often use stack ventilation, which is frequently aided by airing. Exterior wall thermal insulation influences the quality of the natural ventilation system. Insulation reduces air infiltration, and thus disrupts the effectiveness of the natural ventilation system. The research presented in this study was conducted in three kindergartens which varied in terms of their exterior wall insulation. The three considered objects were localized in eastern Europe, in the temperate zone. Relying on the obtained measurement results, analysis of correlation between humidity and CO2 concentration could be conducted. Nearly complete correlation was observed in 61% of the measurements. This fact may constitute a solid basis for the control of natural ventilation. [Copyright &y& Elsevier]

The climatic conditions in Kuwait necessitate almost all buildings to be centrally air-conditioned with the latest HVAC system to provide the comfortable thermal environment for occupants. Mosques are used five times a day for a maximum time span of about half an hour or less for regular prayers. The study period was selected in the month of November when the ambient temperatures are moderate and cooling or heating is not required. The influence of natural draft through doors and other indoor/outdoor air exchange sites was examined for indoor air quality, degree of comfort, and different sorts of satisfaction during prayers. The indoor air quality is of major concern for mental, spiritual, and social satisfaction of the chaotic lifestyle of the present-day community. A weeklong study was conducted to measure temperature, humidity, carbon dioxide, and over 70 volatile organic compounds indoors and in the ambient air in the vicinity of the selected mosque. [ABSTRACT FROM AUTHOR]

Abstract: The characteristics of thermal comfort and indoor air quality (IAQ) in bedrooms, occupants’ perceptions and their impact on sleep quality are not often studied. It becomes even more interesting if climatic conditions allow Naturally/Mechanically Ventilated (NMV) concepts as opposed to Air-conditioning (AC) and this becomes very significant from an energy perspective. This paper reports our findings from such a study conducted in a hot and humid climate. Objective measurements of thermal comfort and IAQ were carried out during sleeping period in 12 NMV and 12 AC bedrooms over a period of 2 months. Questionnaire responses were sought from each subject at the end of the objective measurements to assess their perceptions on thermal comfort and indoor air quality of the bedrooms during sleep and their sleeping conditions. Although the “Historical” and “Immediate” responses for the NMV and AC bedrooms indicate that there was a good level of acceptability for both Thermal Comfort and Perceived Air Quality (PAQ), it was found that NMV bedroom was a better sleeping environment. The subjects’ immediate perception of PAQ and thermal comfort were reasonably correlated with their historical perceptions. The subjects’ perception of PAQ was fairly closely correlated to their perception of Thermal Comfort. There was a considerable increase in the carbon dioxide level in an AC bedroom relative to a NMV bedroom. However, there was no clear evidence to substantiate that sleeping duration decreased with increasing level of carbon dioxide, but the findings do suggest that high level of carbon dioxide may hinder the duration of sleep. [Copyright &y& Elsevier]

Abstract: Nowadays, with the increase in the thermal insulation of buildings, indoor air quality (IAQ) has deteriorated, particularly because of the presence of volatile organic compounds (VOC). To improve IAQ, photocatalytic processes can be used. Photocatalytic reactions can be broken down into three steps: adsorption of pollutants, chemical reaction, and desorption of water, carbon dioxide and by-products. In this work, the accessibility of the pollutants to the reactive sites of a commercial TiO2-photocatalyst is studied. Firstly, adsorption mechanisms are investigated through toluene adsorption isotherms in batch reactors. In humid air conditions (relative humidity of 50% at 24°C), the classical adsorption models cannot be applied. Consequently, a new model, called the “Langmuir-multi”, is built. It fits the obtained experimental data properly. Adsorption equilibrium constants are calculated based on this new model. To understand adsorption mechanisms better, adsorption isotherms are also performed in dry air conditions with toluene and in humid air with acetone and heptane. It is observed that water vapor plays a major role. Secondly, photocatalytic reactions are carried out with toluene, acetone and heptane in humid air. The kinetic curves are well-represented by the Langmuir–Hinshelwood (L–H) equation so that reaction and equilibrium constants can be assessed. The L–H equilibrium constant appears to depend on the type of pollutant and on the affinity between the pollutant and the photocatalyst surface. No correlation is found between the equilibrium constant and light intensity. It is also shown that the calculated L–H equilibrium constants are not equal to those previously obtained in dark conditions and in batch reactors. [Copyright &y& Elsevier]

Abstract: In this paper, the topic of thermal comfort for buildings with double skin façades and single skin façades is demonstrated and discussed. A long-term monitoring was performed in 280 office rooms distributed over 28 buildings in Germany. The survey methods were based on sensor measurements and data simultaneously gathered from questionnaire given to office users. The authors take into consideration the operative temperature, vertical gradient temperature, draught rate, radiation asymmetry, relative humidity and carbon dioxide concentration. The aim is to determine the individual sensory perception of the indoor environment and compare it to the actually measured indoor climate in buildings with double skin façades and single skin façades. In regards to the thermal comfort results, in general, it is shown that double skin façades buildings have slight advantages in relation to single skin façades buildings. [Copyright &y& Elsevier]

Many microenvironmental and behavioral factors can affect concentrations of and exposures to volatile organic compounds (VOCs). Identifying these determinants is important to understand exposures and risks, and also to design policies and strategies that minimize concentrations. This study is aimed at determining factors associated with VOC concentrations found indoors in residences and outdoors in ambient air. It utilizes results from a comprehensive field study in which 98 VOCs were measured both inside and outside of 159 residences in three communities in southeast Michigan, USA. Additional measurements included indoor CO2 concentrations, temperature, relative humidity, building and neighborhood characteristics, and occupant activities, assessed using a questionnaire and comprehensive walkthrough investigation. Factors potentially affecting concentrations were identified using bivariate and multivariate analyses. Outdoors, seasonal and community effects were observed. Indoors, seasonal effects were limited to the urban and industrial communities, largely due to changes in ambient levels. Elevated indoor VOC concentrations were associated with eight sources or activities: the presence of an attached garage; recent renovations; older residences; indoor smoking; less frequent window or door opening; higher CO2 concentrations; and lower ventilation rates. VOC levels were uninfluenced by building materials (wood vs. brick), flooring type (carpeting vs. wood), stove type (gas or electric), number of occupants, air freshener use, and hobbies involving arts and crafts. Factor analyses identified up to five factors for the ambient VOC measurements, and up to 10 factors for the indoor measurements, which further helped to explain the variability of concentrations and associations between VOCs. [Copyright &y& Elsevier]

Studies of the indoor air quality of restaurants have rarely focused on ventilation system performance in relation to air pollutants and climatic factors. This study was conducted in eight restaurants to examine this issue by determining the ventilation flow rates and the levels of carbon dioxide (CO[sub 2]), ambient temperature, and relative humidity during at least one complete shift of serving a meal. The mean values of number of dining patrons, ventilation flow rates, and the levels of CO[sub 2], ambient temperature, and relative humidity were not significantly different in the nonsmoking dining rooms and the smoking dining rooms. The mean ventilation flow rates in individual restaurants ranged from 42-113 cubic feet per minute per person (cfm/person), overall exceeding the recommended lower limit of 30 cfm/person. The mean levels of CO[sub 2] in two restaurants (646 and 819 ppm) were below, and in the other six restaurants (ranging 1012-1820 ppm) were above the recommended upper limit of 1000 ppm. The levels of CO[sub 2] in each restaurant significantly correlated with the number of dining patrons and in four restaurants accumulated gradually over time. In the nonsmoking dining rooms, the levels of CO[sub 2] increased significantly as the ventilation flow rates decreased. The mean ambient temperature in restaurants (ranging from 22°C-24°C) were within the recommended range of 20°C-26°C. The mean relative humidity in six restaurants (ranging from 46%-59%) were within the recommended upper limit of 60 percent, and in two restaurants (62% and 71%) were slightly higher than this recommended limit. It was concluded that although the mean ventilation flow rates in all restaurants exceeded the recommended value, the design of the ventilation system or the distribution of air flow rate in some sections of restaurants were not appropriate to keep the levels of CO[sub 2] and relative humidity at some measurement locations below the recommended limits. [ABSTRACT FROM AUTHOR]