Dynamic Insulation Systems to Control Airborne Transmission of Viruses in Classrooms: A Review of 'Airhouse' Concept

The discovery of the Covid-19 virus in China at the end of 2019 has drastically altered the global landscape. The virus, which has now become a pandemic, has wrought devastation on the world, infecting over 500 million people and killing over 6 million. The virus's mutation into a few variations, however, has enabled the world's alarming situation to continue until now. Airborne particles and viruses including the new Covid-19 variant -Omricon, is not only extremely contagious but also can be transferred by airborne transmission, putting vulnerable people like children at risk, particularly in classrooms. Amongst the strategies to control airborne transmission of viruses and to improve indoor thermal and air quality is using ventilation strategies -such as dynamic insulation. Thus, this paper will review at how dynamic insulation systems in conventional farming and residential buildings, cleanrooms and other controlled environments work to reduce airborne viruses and particles in a room. An innovative "Airhouse" concept that combines with activated carbon has been researched and investigated with regard to the dynamic insulation systems.This system has a high potential to reduce the air temperature, humidity, and airborne viruses including Covid-19 whilst maintaining a steady airflow rate in a normal room. Therefore, it has a great deal of potential to decrease or eliminate concerns about the transmission of airborne viruses and adapt ventilation systems to new pandemic threats.

Evaluation of a Low-Cost Air Renewal System for Indoor Air Quality Control in a Climate Chamber

There is a growing concern about Indoor Environmental Quality (IEQ) in buildings as humans are spending longer in indoor environments, whether this is associated or not with climate change and vulnerability to extreme weather events. In the wake of the COVID pandemic, the need for indoor air quality control is likely to increase, the result of many adaptations in home environments to switch to remote work. In hot countries in the Global South, one of the alternatives is split A/C units with limited air renewal. While, odorless and colorless CO2, commonly generated by occupants through respiration, is among the relevant indoor air pollutants. The purpose of this study is to evaluate a low-cost, responsive air-renewal system in a climate chamber equipped with a standard split A/C unit. The results show the system's feasibility in curbing IAQ concerns and also highlight the risk of negative impacts on indoor thermal conditions and on energy consumption on using A/C. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Soft Ionization: Improving Indoor Air Quality

In this paper we report two applications of a subcategory of air cleaning devices based on soft ionization that do not cause molecular fragmentation. A system that includes two unipolar ionizing modules has been used to simultaneously produce positive and negative ions in the air. In one set of experiments a large chamber (28 m3) was used to study the effect of ions on reducing PM1.0 particles produced by a research grade calibrated cigarette. The data presented in this paper were obtained using a carbon-brush-based bipolar ionizer and a MERV 10 filter with electret media in a recirculating HVAC system. Significant improvement in removal rate of fine and ultrafine particles was achieved when using the bipolar ionizer in conjunction with the MERV 10 filter. The second set of experiments were conducted using a 36 m3 chamber, following BSL-3 standards, to study the effect of ions on aerosolized SARS-CoV-2. Results of these investigations reveal the inactivation rate of SARS-CoV-2 are enhanced when ions are introduced in the air;inactivation rates were increased by more than 60%and 90%for ion densities of 10,000/cc and 18,000/cc. IEEE

Barriers to incorporation of indoor environmental quality (IEQ) principles into building designs

PurposeThis research presents a comprehensive review of the literature on the barriers to incorporating indoor environmental quality (IEQ) principles into building designs. The aim was to identify these barriers in the literature and subsume them under broad categories for the development of a framework showing the interrelationships among the barriers.Design/methodology/approachThe research design used a systematic desktop review which comprised of three levels of screening. The first level allowed for a broad selection of papers;the second level of screening was done to limit the results to papers within the construction industry, and the third level of screening limited the documents strictly to the publication period of 2000–2021.FindingsTwenty-four (24) barriers were identified in the literature, including lack of integrated design teams, which ranked the highest in appearance, high initial costs, poor market for IEQ buildings and higher design charges among others. The identified barriers were classified into six (6) categories namely capacity barriers, economic barriers, process-related barriers, cultural barriers, client-related barriers and steering barriers.Practical implicationsThe findings of this study would enable practitioners and policymakers to better understand what is preventing the widespread adoption of IEQ designs in the built environment and devise actionable strategies to overcome them. It adds to the body of knowledge on IEQ research by categorizing the various barriers that prevent the delivery of IEQ projects.Social implicationsThe developed barriers in this research can serve as a useful checklist to future researchers who may want to validate the barriers to IEQ designs in empirical studies and in different settings.Originality/valueThe interconnectivity revealed by the web-like framework allows for an appreciation of the various barriers of IEQ adoption which would help in expanding the current knowledge on IEQ beyond the narrow scope of isolated barriers. The fact that the papers selected in this study are not limited geographically, underscores the wide applicability of the findings in the global construction industry.

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

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

The effect of ventilation performance on risk of indoor airborne transmission of SARS-CoV-2

Ventilation performance plays a significant role in distributing contaminants and airborne infections indoors. Thus, poorly ventilated public spaces may be at high risk due to the presence of both infectious and susceptible people. Adapting HVAC ventilation systems to mitigate virus transmission requires considering ventilation rate, airflow patterns, air balancing, occupancy, and feature placement. The study aims to identify poorly ventilated spaces where airborne transmission of pathogens such as SARS-CoV-2 could be critical. This study is focused on evaluating the ventilation performance of the building stock and the safety of using the facilities based on measured indoor CO2. The results revealed the spaces with the potential risk of indoor airborne transmission of COVID-19. The study proposes recommendations for utilising air ventilation systems in different use cases. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

The Indoor Air Quality Trilemma: Improving Air Quality, Using Less Energy, and Meeting Stakeholder Requirements

Good indoor air quality (IAQ) is critically important for many aspects of our lives, including as we've found recently in reducing the transmission of airborne diseases such as COVID-19. Delivering good IAQ poses several challenges to organisations: it can require changes in working practices, be bounded by infrastructure capabilities such as buildings and their heating and ventilation systems, and result in substantial energy usage. In this study we have conducted a preliminary investigation measuring IAQ in a typical 'science lab' classroom, and engaging with stakeholders to jointly explore these data. Our mixed methods approach uncovers an indoor air quality 'trilemma', which relates air quality, energy usage, and stakeholder practices that can be mediated by, and understood as, a site for potentially impactful future HCI designs. © 2023 Owner/Author.

Towards improved thermal comfort predictions and higher energy savings: building energy model of an open-plan office based on indoor CO2 and temperature controls

In recent work, a Hierarchical Bayesian model was developed to predict occupants' thermal comfort as a function of thermal indoor environmental conditions and indoor CO2 concentrations. The model was trained on two large IEQ field datasets consisting of physical and subjective measurements of IEQ collected from over 900 workstations in 14 buildings across Canada and the US. Posterior results revealed that including measurements of CO2 in thermal comfort modelling credibly increases the prediction accuracy of thermal comfort and in a manner that can support future thermal comfort prediction. In this paper, the predictive model of thermal comfort is integrated into a building energy model (BEM) that simulates an open-concept mechanically-ventilated office space located in Vancouver. The model predicts occupants' thermal satisfaction and heating energy consumption as a function of setpoint thermal conditions and indoor CO2 concentrations such that, for the same thermal comfort level, higher air changes per hour can be achieved by pumping a higher amount of less-conditioned fresh air. The results show that it is possible to reduce the energy demand of increasing fresh air ventilation rates in winter by decreasing indoor air temperature setpoints in a way that does not affect perceived thermal satisfaction. This paper presents a solution for building managers that have been under pressure to increase current ventilation rates during the COVID-19 pandemic. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Post-Occupancy study of indoor air quality in university laboratories during the pandemic

This post-occupancy study aims to assess the indoor air quality (IAQ) and ventilation performance in workshops and laboratories of a UK university during the COVID-19 pandemic. Supply airflow rates and CO2 were monitored as a proxy for evaluating ventilation performance. Additionally, particulate matter (PM10) was monitored to address the occupant's concerns about dust. Monitoring showed that maximum CO2 values recorded are mostly below 1000 ppm, with weekly averages below 520 ppm. This was expected as the supply airflow rates were significantly larger than recommended 10 l/s per occupant. Despite the large flow rates, PM10 levels in some laboratories were above the threshold value of 50 [μg/m3] supporting the poor IAQ claims of the occupants. The study indicated the room air re-circulation and indoor activities as the likely reasons for the elevated PM10 levels and some practical operational solutions were suggested for IAQ concerns. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Performance of in-duct bipolar ionization devices on pollutant removal and potential byproduct formation in indoor environments

The COVID-19 pandemic has highlighted the importance of indoor air quality (IAQ) since SARS-CoV-2 may be transmitted through virus-laden aerosols in poorly ventilated spaces. Multiple air cleaning technologies have been developed to mitigate airborne transmission risk and improve IAQ. In-duct bipolar ionization technology is an air cleaning technology that can generate ions for inactivating airborne pathogens and increasing particle deposition and removal while without significant byproducts generated. Many commercial in-duct ionization systems have been developed but their practical performance on pollutant removal and potential formation of byproducts have not been investigated comprehensively. The results in this study showed that the in-duct bipolar ionization technology can significantly improve the particle removal efficiency of the regular filter, while no significant ozone and ion were released to the indoor air. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Assessment of diffuse ceiling ventilation performance on transmission of airborne infectious diseases

Ventilation systems have been widely used to satisfy the occupants' indoor air quality and thermally comfort conditions. Various air distribution systems have been developed to supply clean air, including mixing, displacement, and diffuse ceiling ventilation systems. Diffuse ceiling systems are recent air distribution systems that supply cold air to the occupant area using perforated diffuse panels. These systems distribute air with a low velocity, minimizing the draft risk and dissatisfaction in highly dense spaces. The transmission risk of airborne infectious diseases like Covid-19 from the infected patient is high in waiting rooms. Thus, there is a demand to assure a secure environment for medical staff and patients in the waiting rooms. This study aims to numerically investigate the impact of the relative distance of the contamination source and exhaust on the transmission of airborne infectious diseases in the waiting room equipped with the diffuse ceiling ventilation system. In this regard, the release of Covid-19 from 4 different patients was investigated separately using the computational fluid dynamics technique. The distribution of the airborne infectious diseases is simulated by releasing SF6 tracer gas. The simulation result revealed that the contaminated patient located adjacent to the room's outlet had no contamination risk for other patients and staff in the waiting room. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Managing indoor air quality in nursery and primary schools with low-cost solutions

This study aimed to evaluate the feasibility of using low-cost solutions to monitor and mitigate PM2.5 and PM10 concentrations in nursery and primary schools in Porto (Portugal). Three periods were considered: i) early 2020 (before COVID-19 pandemic), ii) early 2021 (during COVID-19 pandemic, with mitigation measures to prevent SARS-CoV-2 spread);and iii) in the middle of 2021 (additionally using a low-cost portable air cleaner). PM2.5 and PM10 were continuously monitored with a low-cost sensing device for at least two consecutive days in five classrooms. In general, the lowest PM concentrations were observed in the third period. Concentrations reduced up to 63% from the second to the third period. The application of low-cost solutions for monitoring and mitigating PM levels seems to be an effective tool for managing indoor air in schools. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

New methodology to qualify office microbial air quality with air-handling-unit-filters

The Covid-19 pandemic reminded us the importance of maintaining adequate indoor air quality to reduce the risk of propagation of viral particles. The aim of this study is to use air handling unit (AHU) filters to develop a methodology to identify microbial contaminants present in office indoor air. The methodology involves discs of filter media collected periodically from the extraction filters and analysed by cultural and molecular methods. Results obtained from the 10 months study indicate in particular that the concentration of cultivable microorganisms on the filters display small variations of 37% from average value for the 5-culture media tested (e.g., 3.9×102 CFU/cm2 for LB medium). The genera Aspergillus, Cladosporium and Penicillium are the most represented among the cultivable microorganisms collected on the extraction filter. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Effectiveness of upper-room UVGI system in a classroom with mixing and displacement ventilation

This study investigates the effectiveness of an upper-room UVGI system in a small classroom. Mixing ventilation can increase virus removal when combined with a UVGI system more effectively than displacement ventilation combined with a UVGI system, especially in cases where the ventilation rate is low. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Indoor Air Quality Improvements to Reduce Global Catastrophic Biological Risk

The importance of indoor air quality (IAQ) to reduce infectious disease transmission has become clear during the COVID-19 pandemic. In addition to SARS-CoV-2, other diseases, including RSV and influenza, are spread by airborne transmission, and often indoors-where most people spend over 90% of their lives. Given the importance of indoor environments in the spread of infectious disease, ventilation and filtration to improve IAQ should play a major role in preparing for a global catastrophic biological risk event (GCBR). This study involves performing a review of peer-reviewed literature and reports about improving indoor air quality in public spaces and interviewing technical experts in the fields of indoor air, building ownership, IAQ policy, and disease transmission control. The goal of the study is to identify and develop near and long-term policy actions for improving IAQ aimed to reduce GCBRs and other infectious diseases at various levels, including local and national. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Heat vs. Health: Home Office under a Changing Climate

Stressors are especially widespread in urban agglomerations. Common themes of built environment interventions that support health and well-being are blue and green infrastructure, indoor and outdoor air quality, thermal comfort, access to natural lighting, and acoustics. Given the current megatrends of increasing summer temperatures and the high popularity of home offices, we aimed at modeling thermal comfort changes of people working at home in three Austrian cities (Vienna, Innsbruck, and Graz) during the next decades until 2090. We present findings based on (I) an inter-disciplinary literature search and (II) indoor and outdoor climate simulations for actual and future climate scenarios. Based on the results, we discuss the potential impacts for work and human health and well-being, and we suggest a framework for the home office in "post-COVID-19 Austria” that integrates social, ecological, and economic aspects. The results of our study indicate that, in future climate scenarios, overheating of the interior can no longer be prevented without active cooling measures and nature-based solutions. Recommendations on the adjustment of behavior under climate change, including greening, adequate ventilation, and cooling techniques, are thus urgently needed for employees who are working from home in order to maintain physical and mental health and wellbeing.

Need of Technological Interventions for Indoor Air Quality and Risk Assessment Upon Short-Term Exposure: A Futuristic Approach

The variation in ambient air pollution hampers indoor air quality (IAQ), and even the short-term variation is very hazardous for the exposed population. Technological interventions including sensors, smartphones and other gadgets are implemented to build smart environments. However, these interventions are still not fully explored in developing countries like India. The COVID-19 pandemic has made it very important to keep a tab on the air we breathe in as those already suffering from respiratory troubles are prone to fall victim to the deadly disease. In such a scenario, even a rise in pollution for a short duration is dangerous to the exposed pollution. Such short-term exposure facilitated by the meteorological creates a disaster for environmental health. The short-term rise in the concentration of pollutants makes things worse for the exposed people, even indoors. It is therefore critical to come up with a concrete solution to predict the IAQ instantly and warn the exposed population which can be only achieved by technological interventions and futuristic Internet of Things-based computational predictions. This chapter is intended to elaborate the health hazards linked to short-term rise in pollutants, which often goes unnoticed but has a critical impact and how with the help of IoT-based applications, the short-term variation can be predicted through different strategies. Similarly, the assessment of the health impact associated with short-term exposure to air pollution is also significant, and different exposure assessment models and computational strategies are discussed in the course of the study. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Energy efficient ventilation and indoor air quality in the context of COVID-19 - A systematic review.

New COVID-19 ventilation guidelines have resulted in higher energy consumption to maintain indoor air quality (IAQ), and energy efficiency has become a secondary concern. Despite the significance of the studies conducted on COVID-19 ventilation requirements, a comprehensive investigation of the associated energy challenges has not been discussed. This study aims to present a critical systematic review of the Coronavirus viral spreading risk mitigation through ventilation systems (VS) and its relation to energy use. COVID-19 heating, ventilation and air conditioning (HVAC)-related countermeasures proposed by industry professionals have been reviewed and their influence on operating VS and energy consumption have also been discussed. A critical review analysis was then conducted on publications from 2020 to 2022. Four research questions (RQs) have been selected for this review concerning i) maturity of the existing literature, ii) building types and occupancy profile, iii) ventilation types and effective control strategies and iv) challenges and related causes. The results reveal that employing HVAC auxiliary equipment is mostly effective and increased fresh air supply is the most significant challenge associated with increased energy consumption due to maintaining IAQ. Future studies should focus on novel approaches toward solving the apparently conflicting objectives of minimizing energy consumption and maximizing IAQ. Also, effective ventilation control strategies should be assessed in various buildings with different occupancy densities. The implications of this study can be useful for future development of this topic not only to enhance the energy efficiency of the VS but also to enable more resiliency and health in buildings.

Indoor air quality in a training centre used for sports practice.

Background: One of the measures for controlling the coronavirus disease 2019 (COVID-19) pandemic was the mass closure of gyms. This measure leads us to determine the differences between indoor and outdoor air quality. That is why the objective of this study was to analyse the indoor air quality of a sports centre catering to small groups and rehabilitation. Methods: The study was conducted in a single training centre, where 26 measurements were taken in two spaces (indoors and outdoors). The air quality index, temperature, relative humidity, total volatile compounds, carbon monoxide, ozone, formaldehyde, carbon dioxide, and particulate matter were measured indoors and outdoors using the same protocol and equipment. These measurements were taken twice, once in the morning and once in the afternoon, with all measurements made at the same time, 10 am and 6 pm, respectively. Additionally, four determinations of each variable were collected during each shift, and the number of people who had trained in the room and the number of trainers were counted. Results: In the different variables analysed, the results show that CO2 and RH levels are higher indoors than outdoors in both measurement shifts. Temperatures are higher outside than inside and, in the evening, than in the morning. TVOC, AQI and PM show less variation, although they are higher outdoors in the morning. CO is highest indoors. HCHO levels are almost negligible and do not vary significantly, except for a slight increase in the afternoon outside. Ozone levels are not significant. All the variables showed practically perfect reliability in all the measurements, except for ozone measured outside in the morning. On the other hand, the variables exhibit variations between indoors and outdoors during the morning and afternoon, except for the three types of PM. Also, the data show that all the main variables measured inside the sports training centre are similar between morning and afternoon. However, outside, temperature, relative humidity and HCHO levels show significant differences between morning and afternoon while no differences are observed for the other variables. Conclusion: The indoor air quality of the training centre assessed was good and met current regulations; some of its components even exhibited better levels than fresh air. This article is the first to measure indoor air quality in a sports training centre catering to rehabilitation and small groups.

Moisture damage and fungal contamination in buildings are a massive health threat - a surgeon's perspective.

OBJECTIVES: Indoor air toxicity is of major public health concern due to the increase in humidity-induced indoor mould exposure and associated health changes. The objective is to present evidence for the causality of health threats and indoor mould exposure. METHODS: PubMed search on the following keywords: dampness, mould, indoor air quality, public health, dampness, and mould hypersensitivity syndrome, sick building syndrome, and building-related illness as well as information from the health authorities of Bavaria and North Rhine-Westphalia, the Center of Disease Control (CDC), World Health Organisation (WHO), and guidelines of professional societies. RESULTS: The guidelines of professional societies published in 2017 are decisive for the assessment of the impact of mould pollution caused by moisture damage on human health and for official regulations in Germany. Until 2017, a causal connection between moisture damage and mould exposure could usually only be established for pulmonary diseases. The health risk of fungal components is apparent as documented in the fungal priority pathogens list (FPPL) of the WHO. Since 2017, studies, especially in Scandinavia, have proved causality between moisture and mould exposure not only for pulmonary diseases but also for extrapulmonary diseases and symptoms. This was made possible by new test methods for determining the toxicity of fungal components in indoor air. Environmental medical syndromes, e.g., dampness and mould hypersensitivity syndrome (DMHS), sick building syndrome (SBS), building-related symptoms (BRS), and building-related illness (BRI), and fungal pathogens, e.g., Aspergillus fumigatus, pose a major threat to public health. CONCLUSION: There is evidence for the causality of moisture-induced indoor moulds and severe health threats in these buildings. According to these findings, it is no longer justifiable to ignore or trivialize the mould contamination induced by moisture damage and its effects on pulmonary and extrapulmonary diseases. The health and economic implications of these attitudes are clear.