Adequate Indoor Air Quality Research Articles

Evaluation of microclimate in dairy farms using different model typologies in computational fluid dynamics analyses

Ventilation plays a key role in the livestock buildings since it is important to guarantee a comfortable environment and adequate indoor air quality for the animals. Naturally ventilated barns are usually characterized by high variability in the ventilation conditions. Moreover, the ventilation efficiency can be very different in different areas of a barn because of the different presence of the animals. On the other hand, appropriate ventilation is an essential requirement to ensure animal welfare and efficient and sustainable production since a proper ventilation is the most efficient way to remove undesirable air pollutants and to obtain a comfortable microclimate for the welfare of the animals. In this regard, the computational fluid dynamic (CFD) simulations represent a powerful and useful tool because they can be used to assess ventilation and microclimate conditions. In this context, the present study has the object to assess whether different CFD modelling approaches (i.e. model with animals modelled as obstacles with closed volume and model enriched with cows modelled as obstacles capable of exchanging heat with the surrounding air volume) show differences in relation to the climatic conditions inside a naturally ventilated dairy barn. The comparison of the results, set in terms of indoor air temperature and air velocity contours of the two different models, arises that if a precise definition of the microclimatic features is necessary, in order to correlate them with production parameters or assess animal welfare indexes, thermal simplification is not acceptable since can lead to completely misleading conclusions and incorrect evaluations. Then, only adopting CFD models considering the animal thermal behaviour is possible to obtain effective information both for the proper barn system management and for the creation of useful tools driving the farmers' choices.

Numerical investigation of indoor thermal comfort and air quality for an office equipped with corner impinging jet ventilation

ABSTRACT This study investigates the feasibility of using only corner impinging jet ventilation (CIJV) for heating and cooling a medium-sized office space with two occupants while maintaining adequate indoor thermal comfort and air quality compared to traditional mixing ventilation systems. This study examines what impact various outdoor temperatures, ranging from −15°C to 25°C, have on an office environment in terms of indoor thermal comfort and air quality. Three different workspace positions were evaluated. The results show that the CIJV system meets the ASHRAE thermal comfort standards for all three positions. In terms of indoor air quality, CIJV performs better than traditional mixing systems, with improved mean age of air and ACE values. This study concludes that CIJV can be used both close and far away from the supply inlets and still provide adequate indoor thermal comfort and air quality during both cooling and heating season.

Energy efficient cooling through natural ventilation in Kosovo

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

Optimal Hybrid Ventilation Strategy to Assure Adequate Indoor Thermal Comfort and Air Quality in Educational Spaces under a Tropical Climate

Air quality, specifically in indoor environments, has become a growing concern. In general, people tend to spend most of their lives indoors due to the growing urbanization. Indoor air quality is associated with ventilation rates, academic performance, and occupant’s health due to the presence of indoor pollutants. Exposure to these contaminants is a risk factor for people to develop the sick building syndrome. The objective of this study was to determine an optimal hybrid ventilation strategy in a tropical climate, favoring natural ventilation with different proposed strategies, varying the opening of doors and windows, the opening time, and the occupancy, among other aspects and strategies using dynamic simulation. The results were compared with in-situ measurements and surveys conducted on students in the case study. Of the proposed strategies, it was decided as optimal hybrid strategy to increase the fresh air intake from 5 L/s*person to 10 L/s*person with the use of mechanical ventilation and reduction of occupancy, this way, in addition to improving indoor air quality, the thermal comfort of the students was ensured.

Monitoring and Assessment of Indoor Environmental Conditions in Educational Building Using Building Information Modelling Methodology.

Managing indoor environmental quality (IEQ) is a challenge in educational buildings in the wake of the COVID-19 pandemic. Adequate indoor air quality is essential to ensure that indoor spaces are safe for students and teachers. In fact, poor IEQ can affect academic performance and student comfort. This study proposes a framework for integrating occupants' feedback into the building information modelling (BIM) methodology to assess indoor environmental conditions (thermal, acoustic and lighting) and the individual airborne virus transmission risk during teaching activities. The information contained in the parametric 3D BIM model and the algorithmic environment of Dynamo were used to develop the framework. The IEQ evaluation is based on sensor monitoring and a daily schedule, so the results show real problems of occupants' dissatisfaction. The output of the framework shows in which range the indoor environmental variables were (optimal, acceptable and unacceptable) and the probability of infection during each lecture class (whether or not 1% is exceeded). A case study was proposed to illustrate its application and validate it. The outcomes provide key information to support the decision-making process for managing IEQ and controlling individual airborne virus transmission risks. Long-term application could provide data that support the management of ventilation strategies and protocol redesign.

Users' Perception of Comfort Experienced in Academic Buildings of Selected Universities in Ogun State, Nigeria

In architectural design, the level of comfort experienced in the spaces created serve as one of the units of measurement in assessing a complete design. In a country tropical climate such as Nigeria, indoor environmental conditions are primarily influenced by many factors, including lighting, ventilation, indoor air quality, sound quality and building materials employed. This study investigated users’ comfort satisfaction level in relation to environmental design consideration factors in academic buildings of selected universities in Ota, Ogun State, Nigeria, with a view to identify areas for improvement towards making contributions that will help to improve users’ satisfaction in the development of academic environments. The study adopted a quantitative research method that used a structured questionnaire to collect data from 291 respondents, out of which 271 are students and 19 are lecturers. The users’ sample size was drawn from the Department of Architecture students and lecturers of two selected universities in the study area. The data were analyzed with the aid of Statistical Product and Service Solutions software and presented descriptively with the aid of tables. The results showed that majority of the respondents in the selected universities attested to the adequacy of the four environmental design consideration factors investigated, with the factors recording various levels of adequacies. In few areas were the factors were inadequate, the foremost reason was the inadequacy of the indoor air quality, followed by that of lighting before ventilation. Also, daylighting in classrooms and ventilation in offices was found to be inadequate in one of the universities, while the inadequacy of ventilation in offices in the other university was significantly high. The study recommended that building industry designers should pay more attended to means of achieving adequate indoor air quality, lighting and ventilation in academic buildings, without compromising achieving adequacy of sound quality found to be generally satisfactory. The study has implications for policy formulation, designs and researches that strive towards meeting users’ comfort satisfaction level in the development of academic environments.

Pollutant Emissions in Livestock Buildings: Influence of Indoor Environment, Rearing Systems, And Manure Management

The issue of air pollutants from livestock buildings is prevalent in the literature. Because they and their emissions impact both animal production and livestock building users as well as the outdoor environment. This paper aims to compile and review data available in the scientific literature on the types of pollutants for a better understanding of their generation form, their distribution according to the kind of animal, and the main factors affecting their generation and concentration, i.e., the rearing system, the indoor microclimate, and the manure management. The elevated generation of pollutants in animal buildings is tied to the dense occupancy in this industrial activity. The indoor air quality is defined according to the type of livestock in animal housing, considering its welfare needs, and the types and concentrations of pollutants generated as a function of the family of animal and the management used in production. The main gases generated are CH4 , CO2 , H2 S, NH3 , N2 O, in addition to particulate matter and airborne microorganisms such as fungi and bacteria that very negatively affect the health of animals and users of the animal buildings. Furthermore, knowledge about the main contaminants generated, the form of generation, their origin, their concentrations, and their distribution throughout the shed is essential to achieve a permanent and adequate indoor air quality and, with that, a high-quality product that will lead to high production yield without neglecting animal welfare.

Indoor air quality analysis in naturally ventilated university training laboratories: a health risk assessment

The indoor air quality (IAQ) of eleven naturally ventilated training laboratories was analysed to evaluate the health risk to occupants. IAQ evaluation included analysis of physical (temperature (T) and relative humidity (RH)), chemical (CO2, CO, O3, total volatile organic compounds (TVOC), and particulate matter (PM)) and microbiological (fungi and bacteria) pollutants. Monitoring was carried out in labs used for teaching different academic disciplines (biology, chemical, ecology, and computers) during two periods of the academic year. Ventilation rates (VR), air change per hour (ACH) in every lab, and the hazard quotients for each of the chemical pollutants and the accumulated (HQ and HI) were calculated. Environmental comfort was not fully satisfactory considering the RH and CO2 values, especially during hours with higher occupancy. Coarse particles and bacteria were generated indoor related to human activity. At chemical and biological laboratories, TVOC concentrations were sometimes above the recommended value, and all the labs presented VR below the European guideline’s recommendations. Results from this study show natural ventilation is not enough to get an adequate IAQ, although no significant non-carcinogenic risk was estimated. However, installation of complementary ventilation systems would be advisable to avoid health risk by acute short-term exposure.Graphical abstract

A review of strategies and their effectiveness in reducing indoor airborne transmission and improving indoor air quality

Airborne transmission arises through the inhalation of aerosol droplets exhaled by an infected person and is now thought to be the primary transmission route of COVID-19. Thus, maintaining adequate indoor air quality levels is vital in mitigating the spread of the airborne virus. The cause-and-effect flow of various agents involved in airborne transmission of viruses has been investigated through a systematic literature review. It has been identified that the airborne virus can stay infectious in the air for hours, and pollutants such as particulate matter (PM10, PM2.5), Nitrogen dioxide (NO2), Sulphur dioxide (SO2), Carbon monoxide (CO), Ozone (O3), Carbon dioxide (CO2), and Total Volatile Organic Compounds (TVOCs) and other air pollutants can enhance the incidence, spread and mortality rates of viral disease. Also, environmental quality parameters such as humidity and temperature have shown considerable influence in virus transmission in indoor spaces. The measures adopted in different research studies that can curb airborne transmission of viruses for an improved Indoor Air Quality (IAQ) have been collated for their effectiveness and limitations. A diverse set of building strategies, components, and operation techniques from the recent literature pertaining to the ongoing spread of COVID-19 disease has been systematically presented to understand the current state of techniques and building systems that can minimize the viral spread in built spaces This comprehensive review will help architects, builders, realtors, and other organizations improve or design a resilient building system to deal with COVID-19 or any such pandemic in the future.

Development and optimization of highly efficient heat recoveries for low carbon residential buildings

To achieve energy efficiency and lower carbon emissions, building envelopes have become tighter and more insulated. These buildings must have mechanical ventilation with high efficient heat recovery to provide adequate indoor air quality using low energy in cold climates, and requirements for heat recovery efficiency are expected to increase. Today’s aluminum heat wheels, one of the most commonly used heat recovery systems, may not be capable of providing such a high efficiency due to the presence of longitudinal heat conduction. This study focuses on developing highly efficient heat wheels by reducing the longitudinal heat conduction and enhancing heat transfer in different channel shapes and matrix materials for heat wheels. Previously often neglected, but in large heat wheels, the longitudinal heat conduction can result in a significant efficiency reduction effect. The highly efficient heat wheels are sought via parametric analysis, experimental verification, and optimization in this study. Reducing matrix wall thickness for high conductive materials and using low conductive materials can significantly improve temperature efficiency. The calculated and experimental results show that the developed plastic and stainless steel heat wheels can exhibit high temperature efficiency of over 90% with acceptable pressure drops. However, stainless steel's high cost and stiffness may limit its use in heat wheels. Wheels made of plastic with circular channels that are symmetrical could be a promising solution to meet the high temperature efficiency needs of the future. Additionally, the optimization shows that the temperature efficiency of plastic heat wheels is more sensitive to design parameters than aluminum or stainless-steel wheels.

Development of a back-propagation neural network combined with an adaptive multi-objective particle swarm optimizer algorithm for predicting and optimizing indoor CO2 and PM2.5 concentrations

People now spend between 80% and 90% of their lifetimes in indoor locations such as offices and residential buildings. These extended hours indoors have substantial health impacts, making it vital that people have adequate indoor air quality (IAQ). The management of IAQ presents two issues: (1) rapidly predicting and controlling IAQ using current intelligent ventilation systems is difficult, and (2) simultaneously controlling both gas pollutants (of which CO2 is a representative example) and particulate matter concentrations (for example, PM2.5) while achieving optimal outcomes is challenging. Therefore, this study aims to develop a fast and accurate optimization algorithm to simultaneously predict and control indoor CO2 and PM2.5 concentrations. To this end, a back-propagation neural network (BPNN) combined with an adaptive multi-objective particle swarm optimizer (AMOPSO) algorithm based on computational fluid dynamics (CFD) is proposed. The CFD model first creates a database of indoor CO2 and PM2.5 concentrations. Then, based on the CFD database, the BPNN model is used to predict indoor air pollutant concentrations. If the predicted concentrations do not meet predetermined limits, the AMOPSO algorithm is initialized to optimize the concentrations of the indoor air pollutants. In test examples, the proposed optimization algorithm reduces CO2 concentrations by up to 30.5%, while also reducing PM2.5 concentrations by as much as 77.1%.

Natural ventilation in classrooms for healthy schools in the COVID era in Mediterranean climate

Indoor air quality in schools has a direct impact on the performance and wellbeing of students. In 2020, the health emergency required the reconsideration of ventilation conditions in indoor spaces, especially for educational buildings. This paper advances previous investigations to identify affordable, sustainable, and healthy designs for the refurbishment and new construction of schools, analysing the design parameters of the buildings and the indoor air quality in a representative sample of schools in the Mediterranean climate. The set of schools represents the regional composition regarding ages, daily scholar schedules and building designs. This study evaluates indoor CO2, TVOCs, PM 2.5 and PM 10, concentration profiles regarding indoor temperature, relative humidity, and occupation rates to identify adequate natural ventilation strategies. The results show a wide dispersion in CO2 concentrations, ranging between 4110 and 5366 ppm (peak values), TVOC mean concentration varies from 206.99 μg/m3 to 589.71 μg/m3 and particulate matter fractions ranging between 1.14 and 15.6 μg/m3 for PM 2.5 and 2.04 and 34.86 μg/m3 for PM 10 during the occupancy period. Concentrations are related to the effect of ventilation actions, the occupation rates and the metabolism of occupants. The combination of values shows how natural ventilation designs can assure adequate indoor air quality within comfort conditions under these mild climate conditions.

Ventilation System Design and the Coronavirus (COVID-19)

Most new office buildings in Nordic countries are equipped with balanced mechanical ventilation systems. The purpose of ventilation in office buildings is to provide thermal control by supplying cold or warm air for adequate indoor air quality. However, the role of ventilation in preventing virus transmission and maintaining a sufficient fresh air supply to obtain a low virus level through dilution is not currently well defined. Ventilation in office buildings is expected to contribute to preventing the spread of contaminants and provide comfort for occupants. The study reveals differences between risk areas for spreading airborne contaminants in office buildings in northern Europe, including Denmark, Norway and Sweden. The differences in the spread depends on different ventilation designs used in different countries.

Adequate indoor air quality in nursing homes: An unmet medical need

A small but growing body of literature indicates that concentrations of indoor particulate and gaseous pollutants in long-term care facilities (i.e., skilled nursing facilities) for older adults, hereafter referred to nursing homes, often exceed those recorded in nearby, comparable outdoor environments. Unlike the outdoors, indoor air quality (IAQ) in nursing homes is not regulated by legislation and is seldom monitored. To that end, residents of nursing homes commonly spend the vast majority of their time indoors where they are exposed to indoor air pollutants for long periods of time. Given that many nursing home residents, especially those of advanced age, are more susceptible to the effects of air pollutants, even at low concentrations, this prolonged exposure may adversely affect their health, well-being, quality of life and increase medical expenditures due to frequent, unscheduled acute care visits and hospitalizations. We propose an action plan for assessing IAQ in nursing homes, understanding the impacts of IAQ on adverse health outcomes of nursing home residents, and addressing vulnerabilities in these facilities to safeguard health, well-being, and quality of life of nursing home residents and minimizing unscheduled acute care visits and hospitalizations. We propose that IAQ should be regularly monitored in nursing homes to proactively identify and address vulnerabilities in these facilities and that resources should be provided for remedial interventions to improve IAQ in nursing homes, including but not limited to source control, improving ventilation and filtration, and deploying air cleaners where appropriate. This proactive approach may pave the way for establishing enforceable standards for indoor air quality in nursing homes that will promote health, well-being, and quality of life of nursing home residents and reduce medical expenditures.

Providing Healthy Air and Efficient Heating for Rural Alaska Homes with the BrHEAThe System

Abstract BrHEAThe is a combined heating and ventilation system designed to ensure adequate indoor air quality in small, efficient, airtight homes in Alaska. The system addresses issues faced by rur...

Ventilation and Filtration Control Strategy Considering PM2.5, IAQ, and System Energy

Ventilation or filtration control is widely applied to improve indoor particle matter (PM) concentration. Adjusting the ventilation rates to control indoor PM levels can affect the concentration of other indoor pollutants and energy costs, and increasing the filtration flow rate can lower the indoor PM concentration, but also increase the fan energy consumption. In this study, we developed a ventilation and filtration control strategy to determine the optimal control mode and flow rate of the system to meet indoor PM (especially PM2.5) concentration, ensure adequate indoor air quality (IAQ), and minimize fan energy consumption. First, a dynamic model to estimate the indoor PM2.5 generation rate was developed based on the mass balance model and then verified by experiments. Next, the control limit (CL) curve was developed on the basis of the indoor PM2.5 characteristics depending on ventilation and filtration control during various indoor and outdoor PM2.5 conditions (indoor PM2.5 generation rate and outdoor PM2.5 concentration). In addition, an algorithm was proposed to determine the optimal control mode and flow rate of the system. Condition zone control can keep indoor PM2.5 below or as close to the desired target concentration as possible, maintain IAQ within acceptable ranges, and save about 15~70% of fan energy compared with the conventional rule-based control under the case condition.

Contribution of indoor microenvironments to the daily inhaled dose of air pollutants in children. The importance of bedrooms

Indoor air quality plays an important role in children's wellbeing and performance. The primary attention of previous research is focused on the air quality in school environments, but time at school only represent 27% of the daily schedule. This paper analyses a broad spectrum of volatile organic compounds and aldehydes in different indoor microenvironments, according to typical children's daily routines, aiming at identifying potential indoor air pollutants and obtain valuable information about the contribution of each indoor microenvironment to the global daily exposure and the inhaled dose of air pollutants in children. High priority pollutants were monitored through passive techniques in 18 indoor microenvironments associated with 3–12-year-old schools, 12-18-year-old schools, and private homes located in Southern Spain. Air pollutant concentrations are compared with the recommended indoor air guideline values (IAGVs) reported by different standards and health organisations. The results show adequate indoor air quality values, within the ranges recommended by guidelines, and highlight the importance of monitoring benzene and formaldehyde to minimise adverse health effects, especially in homes, whose microenvironments are responsible for 88% of the inhaled dose of measured VOCs and aldehydes. Moreover, special attention should be taken of bedrooms, whose air pollutant concentrations are responsible for approximately 60% of the total inhaled dose of VOCs and aldehydes in children. Specific measures should be considered by public health authorities and other policymakers on how to develop and strengthen indoor air quality policy to protect and promote health in the housing stock.

Definition of Optimal Ventilation Rates for Balancing Comfort and Energy Use in Indoor Spaces Using CO2 Concentration Data

Air ventilation rate plays a relevant role in maintaining adequate indoor air quality (IAQ) conditions in public buildings. In general, high ventilation rates ensure good indoor air quality but entail relevant energy consumption. Considering the necessity of balancing IAQ and energy consumption, a correlation between the number of occupants obtained from analysis of CO2 concentration variation is presented as a general element for controlling the operation of heating ventilation and air cooling (HVAC) systems. The specific CO2 exhalation rate is estimated using experimental data in some real conditions in university classrooms. A method for the definition of optimal values of air exchange rate is defined, highlighting that the obtained values are much lower than those defined in current technical standards with possibilities of relevant reduction of the total energy consumption.

Chemical Pollution in Healing Spaces: The Decalogue of the Best Practices for Adequate Indoor Air Quality in Inpatient Rooms.

Indoor air quality (IAQ) is one of the main topics in which governments are focusing. In healthcare facilities, several studies have reported data analysis and case studies to improve users’ health. Nowadays, although many studies have been conducted related to the biological and physical risks, the chemical risks have been less investigated and only in some specific functional areas of the hospitals. Starting from some systematic reviews and research works, this paper aims to list the best healthy practices for an adequate IAQ in inpatient wards. In particular, the decalogue lists the strategies related to chemical pollution, starting from design and management, with a focus on (a) localization of hospitals and inpatient rooms, (b) hospital room, (c) microclimatic parameters, (d) ventilation systems, (e) materials and finishing, (f) furniture and equipment, (g) cleaning products and activities, (h) maintenance and (i) management activities, and (l) users and workers. The multidisciplinary approach emphasizes the need for interdisciplinary knowledge and skills aimed to find solutions able to protect users’ health status. The design and management decision-making, ranging from the adequate choices of construction site and hospital exposure, finishing materials, cleaning and maintenance activities, etc., which can affect the IAQ must be carried out based on scientific research and data analysis.

Assessment of CO2-based demand controlled ventilation requirement for a flexible work environment with ductless split air conditioners

Use of ductless split air conditioners in small workspaces leads to accumulation of carbon dioxide due to the absence of fresh air entry. Additional mechanical ventilation is required to meet the ASHRAE standard. Providing constant-rate ventilation would reduce the CO2 concentration but would lead to high energy consumption when there is variation in occupant density. Instead, demand-controlled ventilation, that is, ventilation rate linked with the occupant density, can reduce energy consumption and maintain adequate indoor air quality. The purposes of this study were to quantify the temporal variation of CO2 in a workspace, to determine the factors influencing the demand-controlled ventilation strategy, and to assess its performance in workspaces with flexible work environment (varying occupant density with time). A parametric study on demand-controlled ventilation design indicates that the ventilation cycle time depends significantly on the occupant density and the range of threshold levels of CO2. The occupants can decide the lower CO2 threshold level based on the requirements. Use of a lower CO2 threshold limit of 700 ppm in a typical workspace with varying occupant density resulted in an energy saving of around 90% when compared with the ventilation rate required by ASHRAE 62.1. The assessment would be helpful in identifying the workspaces that do not require external ventilation. The ventilation design strategy thus developed would help the building managers in improving indoor air quality and lowering energy costs when compared with the constant rate ventilation system.