Enhancement Of Indoor Air Quality Research Articles

Enhancing Indoor Air Quality: Examination of Formaldehyde Adsorption Efficiency of Portable Air Cleaner fitted with Chemically-Treated Activated Carbon Filters

The pursuit of salubrious living environments necessitates a holistic approach to assuring indoor air quality. This entails considering not only particulate matter but also gaseous pollutants, particularly formaldehyde – a carcinogenic and prevalent pollutant in household environment. In addressing the persistent challenge in balancing efficiency, operating costs and environmental impact in formaldehyde removal, our study pioneers to empirically explore and compare the relationship between Carbon Tetrachloride Activity (CTC), Clean Air Delivery Rate (CADR), and Cumulate Clean Mass (CCM) in the context of formaldehyde adsorption, using both raw and 2-Imidazolidone-treated activated carbon (AC) filters fitted in a Portable Air Cleaner (PAC). Our experimental results show that the formaldehyde CADRs of an air cleaner with chemically-treated CTC70 and CTC100 filters were about 251 m3/h and 286 m3/h respectively, representing an increase of 1.52 and 2.5 times over untreated filters, with the treated CTC100 AC filters outperforming the CTC70 filters by approximately 12 percent under new condition. While the precise mechanisms by which 2-Imidazolidone enhances the performance of AC filters are still unknown, these findings provide an first-of-its-kind directive for future research on the interplay among the parameters (CTC, CADR and CCM) of PACs, casting a foundation for further investigations that aim at optimizing the performance of AC filters, thereby making significant strides in the enhancement of indoor air quality.

Enhancement of Indoor Air Quality with a Displacement Ventilation System Comprising a 4-Way Fan Coil Unit and Multiple Air Purifiers

In indoor spaces without mechanical ventilation systems, a common approach involves using a ceiling-mounted 4-way fan coil unit (4WFCU) to regulate indoor temperature and placing floor-level air purifiers (APs) to remove indoor pollutants. This study introduces a differentiated displacement ventilation system (DVS) that connects multiple APs to the 4WFCU using ductwork. The age of air was compared between the case where the newly designed DVS was implemented and the reference case where 4WFCU and APs operated independently. When there were no obstacles in the office central area, the reference system exhibited a lower age of air. Conversely, when obstacles such as desks and partitions were present in the central area, the proposed DVS was found to improve indoor air quality. The DVS resulted in minimal interference among pathlines of the air discharged from multiple floor-level APs and their efficient suction through the ceiling-mounted 4WFCU and diffusers, significantly reducing stagnant air zones, while pathlines of the air discharged from the 4WFCU and APs interfered significantly when they operated independently, leading to larger stagnant areas in the air distribution. Therefore, modifying office spaces with ceiling-mounted 4WFCUs using the proposed DVS is anticipated to substantially enhance indoor air quality through a straightforward installation process.

DeepVision based detection for energy-efficiency and indoor air quality enhancement in highly polluted spaces

Cooking can generate substantial heat from cooking equipment, potentially resulting in reduced thermal comfort levels if this excess heat is not adequately dissipated. Additionally, it can significantly affect indoor air quality (IAQ), not only in kitchen spaces but also in adjacent areas lacking sufficient ventilation. To ensure a healthy and comfortable indoor environment while avoiding unnecessary energy use, this research proposes an approach for detecting equipment usage. Utilizing deep learning and computer vision techniques (referred to as DeepVision), this method aids the operation of demand-driven ventilation systems in highly polluted spaces. A Faster RCNN model was employed and trained to detect kitchen equipment usage in real-time. The ventilation rate for the kitchen space was adjusted based on this real-time detection. Experimental tests were carried out in a case study kitchen and results showed that the detection model achieved an overall F1 score of 0.9142. Overall, the model achieved good performance in real-time detection, accurately identifying appliances in use, such as stoves, ovens, and toasters. Field experimental results showed the advantages of combining mechanical ventilation methods, such as extractor fans and cooker hoods, to mitigate IAQ issues while also achieving energy savings. Moreover, the energy simulations demonstrate its potential to reduce energy consumption by dynamically adjusting ventilation rates in response to real-time equipment usage. When the fan speed was varied according to the real-time detection method, the PM2.5 concentration in the cooking period was 16.5 % lower, with only a 3.7 % rise in fan power and a 0.8 % rise in daily heating demand, compared to using a constant fan speed.

Window Planning for Healthier Workplaces: IAQ Enhancement and Performance Benefits

Abstract: Indoor Air Quality (IAQ) significantly impacts the health and productivity of individuals within built environments. The complex interplay between building design elements, IAQ parameters, and their influence on human well-being has spurred extensive research endeavors. Understanding the effects of architectural configurations, window orientation, and integration of green spaces on IAQ remains crucial for optimizing indoor environments. This research aimed to investigate the impact of building design on IAQ and subsequently on human health and productivity. The study focused on analyzing IAQ parameters concerning various architectural settings, window orientations, and the inclusion of green spaces. The primary objectives were to assess IAQ variations across different spatial configurations, understand the influence of window orientation, and explore the effects of green elements on IAQ and occupant experiences.

Analyzing the Bake-Out Effect in Winter for the Enhancement of Indoor Air Quality at New Apartments in UAE

Indoor air pollution has become a pressing issue in the United Arab Emirates (UAE) due to poor ventilation, inadequate airtightness, and using chemicals in building materials. Accordingly, the UAE is currently experiencing more cases of sick building syndrome (SBS) than any other country. This study aims to assess the effectiveness of the bake-out strategy in reducing indoor air pollutants in a new apartment building in the UAE. The study evaluated a reduction in toluene (C7H8), ethylbenzene (C8H10), xylene (C8H10), styrene (C8H8), and formaldehyde (HCHO) at room temperature and relative humidity. The airtight unit without winter bake-out had higher indoor concentrations of hazardous chemicals than the ventilated units, and the emission of dangerous substances increased with temperature. Moreover, harmful chemicals were only effectively reduced with ventilation times of at least seven days after the heating period. The release rate of contaminants after the bake-out was lower than before. The indoor concentration of hazardous chemicals was lower when bake-out and mechanical ventilation were combined, resulting in a reduction of 92.8% of HCHO. Furthermore, units with a certain amount of ventilation maintained a low indoor pollutant concentration, regardless of whether a bake-out was performed.

Adsorption of Carbon Dioxide by Metal Organic Framework for Indoor Air Quality Enhancement

Air pollution has become a severe environmental issue among millions of people around the globe. However, the risk of exposure to indoor air pollution is much higher than outdoor air pollution. The most effective way to improve indoor air quality (IAQ) by reducing the indoor CO2 content is by capturing and storing. There are several types of adsorbents used to capture CO2, namely physical adsorbents and chemical adsorbents. Metal-Organic Framework (MOF) is one of the recent interests arising physical adsorbents which possesses high adsorption capability. In this study, MOFs fabricated with different metals and organic ligands were used to evaluate their performance in CO2 adsorption under an enclosed office space. Magnesium, chromium, and copper metals were used as the main element in the MOF fabrication coupled with trimesic acid as an organic ligand. The MOFs’ morphologies generally illustrated that magnesium MOF exhibited a dispersed nanorod flask crystal, chromium MOF showed agglomeration crystal, whereas fine crystal rod was observed in copper MOF. The elemental analysis from EDX and XRD confirmed that the metals were successfully embedded with the organic ligand, which is similar to the literature studies. The CO2 gas adsorption study suggested that magnesium MOF fabricated with trimesic acid possess superior CO2 adsorption capability as the recorded CO2 concentration reduced from 960 ± 73 ppm to 895 ± 57 under 2 hours continuous sampling time. The CO2 adsorption study reveals that the magnesium MOF with trimesic acid ligand yields a promising result on indoor CO2 concentration reduction. This result suggested that the MOF possesses a great potential to be applied in the indoor air quality enhancement with the integration to the existing air purification and/or filtration system.

Indoor Air Pollution, Related Human Diseases, and Recent Trends in the Control and Improvement of Indoor Air Quality.

Indoor air pollution (IAP) is a serious threat to human health, causing millions of deaths each year. A plethora of pollutants can result in IAP; therefore, it is very important to identify their main sources and concentrations and to devise strategies for the control and enhancement of indoor air quality (IAQ). Herein, we provide a critical review and evaluation of the major sources of major pollutant emissions, their health effects, and issues related to IAP-based illnesses, including sick building syndrome (SBS) and building-related illness (BRI). In addition, the strategies and approaches for control and reduction of pollutant concentrations are pointed out, and the recent trends in efforts to resolve and improve IAQ, with their respective advantages and potentials, are summarized. It is predicted that the development of novel materials for sensors, IAQ-monitoring systems, and smart homes is a promising strategy for control and enhancement of IAQ in the future.

Indoor Air Quality Enhancement Performance of Liquid Desiccant and Evaporative Cooling-Assisted Air Conditioning Systems

The main objective of this study is to investigate the indoor air quality enhancement performance of two different liquid desiccant and evaporative cooling-assisted air conditioning systems, such as the variable air volume (VAV) system with the desiccant-enhanced evaporative (DEVap) cooler, and the liquid desiccant system with an indirect and direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS), compared with the conventional VAV system. The transient simulations of concentration variations of carbon dioxide (CO2), coarse particles, and fine particles (PM10 and PM2.5) in a model office space served by each system were performed using validated system models that were found in the literature. Based on the hourly thermal loads of the model space predicted by the TRNSYS 18 program, each air conditioning system was operated virtually using a commercial equation solver program (EES). The results indicated that the LD-IDECOAS provided the lowest annual indoor CO2 concentration among all the systems considered in this research, while the VAV system with DEVap cooler exceeded the threshold concentration (i.e., 1000 ppm) during the cooling season (i.e., July, August, and September). For the indoor particulate contaminant concentrations, both liquid desiccant and evaporative cooling-assisted air conditioning systems indicated lower indoor PM2.5 and PM10 concentrations compared with the reference system. The LD-IDECOAS and the VAV with a DEVap cooler demonstrated 33.3% and 23.5% lower annual accumulated indoor PM10 concentrations than the reference system, respectively. Similarly, the annual accumulated indoor PM2.5 concentration was reduced by 16% using the LD-IDECOAS and 17.1% using the VAV with DEVap cooler.

Comparative Evaluation of Sustainable Design Based on Step-Wise Weight Assessment Ratio Analysis (SWARA) and Best Worst Method (BWM) Methods: A Perspective on Household Furnishing Materials

For a few years, there has been an increasing consciousness to design structures that are concurrently economic and environmentally responsive. Eco-friendly inferences of building designs include lower energy consumption, reduction in CO2 emissions, assimilated energy in buildings and enhancement of indoor air quality. With the aim of fulfilling design objectives, designers normally encounter a situation in which the selection of the most appropriate material from a set of various material alternatives is essential. Sustainability has been developing as a new concept in all human activities to create a better balance between social, environmental and economic issues. Designing materials based on the sustainability concept is a key step to enable a better balance because there is no need to re-structure phases and procedures to make the system more efficient in comparison to previous models. Some of the most commonly used materials are household furnishing materials, which can be electrical devices, kitchen gears or general furnishing materials. The volume of production and consumption of these materials is considerable, therefore a newer sustainable plan for a better designed system is justifiable. In the literature, the application of multi-attribute decision-making (MADM) methods has been found to be very suitable for evaluating materials and developing general plans for them. This study contributes by applying two approaches based on MADM methods for weighting the criteria related to the sustainable design of household furnishing materials. Step-Wise Weight Assessment Ratio Analysis (SWARA) and Best Worst Method (BWM) are two specialized and new methods for weighting criteria with different approaches. This paper has not only investigated the weighting of important and related criteria for sustainable design but has also evaluated the similarities and differences between the considered weighting methods. A comparative study of SWARA and BWM methods has never been conducted to date. The results show that, except pairwise comparisons, SWARA and BWM are certainly similar and in some cases SWARA can be more accurate and effective.

A new simplified method for decreasing contaminants in underground enclosed parking lots

One of the main concerns in large enclosed vehicular spaces such as parking lots is air contaminant management. Mechanical ventilation systems are typically used to decrease the contaminants and enhance indoor air quality in such spaces. International standards have suggested the amount of ventilation air and have emphasized that the ventilation system should be able to effectively reduce the contaminants, but the reduction in contaminants has not been quantitatively described. This study develops a simplified method for the quantification of contaminant removal and its effect on the enhancement of indoor air quality. This method is based on the numerical calculation of contaminant removal effectiveness in parking lots and changing the location of outlet vents. The results of this work indicate that using a constant ventilation rate, outlet vents are installed at an appropriate height, the flow pattern is improved and contaminant removal effectiveness is enhanced significantly. The numerical results show that the outlet vents should be installed between 50 and 70% of the parking lot ceiling height. By adopting this criterion, a displacement flow pattern is developed in the parking lot, and improvement in both contaminant removal effectiveness and indoor air quality is achieved. Practical application: This paper helps ventilation designers to enhance the air quality of enclosed parking lots by a simple practical method. The designer should only install the outlet vents at the range of heights proposed in this paper to develop displacement flow in the parking lot, which leads to an effective decrease in contaminants and reduce energy consumption. So, the aim of this research is to maximize the contaminant removal capacity and minimize the energy consumption of the ventilation system.

Empirical analysis of indoor air quality enhancement potential in a liquid-desiccant assisted air conditioning system

The main purpose of this research was to empirically investigate the removal of volatile organic compounds (VOCs), airborne particles, and microorganism contaminants from air conditioned by a liquid-desiccant (LD) dehumidifier. The dehumidifier was used in an existing liquid-desiccant evaporative cooling–assisted 100% outdoor air system (LD-IDECOAS) using both direct and indirect evaporative coolers. The ventilation efficiency of the LD-IDECOAS was also measured via a tracer-gas test with carbon dioxide. The concentrations of two representative VOCs, toluene and formaldehyde, the number of particles with various sizes, and the colony-forming units of microorganisms such as bacteria and fungi in the process air were measured before and after liquid-desiccant dehumidification. Then, the measurement results were compared with those acquired by bypassing the liquid-desiccant unit in order to verify the impact of the liquid desiccant on air-contaminant removal. The experimental results showed that the removal efficiency of the LD unit was 36% for toluene, and 29.6% for formaldehyde. The particle-removal efficiencies measured as part of this research were 48.2%, 64.1%, and 84.9% for the particle sizes of 2.5–5 μm, 5–10 μm, and 10–25 μm, respectively. The bacteria-removal efficiency was 77.5% and 81.3% for the sampling process air of 200 and 500 L, respectively, while the fungi removal efficiency was 38.8% and 44.4% for 200 and 500 L of sampling process air, respectively. In addition, the LD-IDECOAS provided an air change rate approximately 3.1 times higher than that of the VAV system when both systems delivered the supply air to the test chamber at the same rate.

Experimental evaluation of VOC removal efficiency of a coconut shell activated carbon filter for indoor air quality enhancement

The present study evaluated the performance of a commercially available activated carbon filter for VOC removal from air through the analysis of real samples. The filter was tested for VOC reduction efficiencies in a PVC portable inflatable bubble provided with an air purifier system called Airbox II Phase by Zonair3d, as described hereinafter. The filter was placed in the Airbox II Phase of the bubble, between a pre-filter and a particulate HEPA H14 filter. Simultaneous duplicate samples were taken from the input air duct before the driving system and from the bubble. VOC were dynamically sampled during 2-h control periods by connecting custom packed glass multi-sorbent cartridge tubes (Carbotrap, Carbopack X and Carboxen 569) to air pump samplers. A validated analytical method based on TD-GC/MS was used to quantify a wide variety of VOC families (alkanes, aromatic hydrocarbons, alcohols, ketones, halocarbons, aldehydes, esters, terpenes, ethers, glycols and nitrogenated compounds). VOC family removal efficiencies ranged from 51 ± 19% to 78 ± 22% with input indoor air, and from 42 ± 16% to 91 ± 18% with input outdoor air. No significant differences in reduction efficiencies (t-test; p < 0.05) were observed between using indoor or outdoor air. Several aldehydes were desorbed from the filter at low concentrations (0.09–21.19 μg m−3) when outdoor air was used as input air. Ozone removal efficiency was assessed by a continuous monitoring system. A 100% yield was obtained in all cases where ozone was present.

Hotel Indoor Air Quality Enhancement: Research Agenda

The article reports on the penetration of polluted outdoor air into hotels and the subsequent deterioration of indoor air quality (IAQ). Little attention has been paid to the severity of this problem. Thus, the study specifically aims to assess the determinants to enhance IAQ in hotels and suggest a future research direction relating to IAQ enhancement. Evidence from recent air pollution studies in hotels located in the Pearl River Delta is synthesized and further augmented by studies in other cities in the territories. Six determinants that motivate the enhancement of hotel IAQ have been identified, including poorer IAQ in new hotels, worsening atmospheric air quality in cities, environmental tobacco smoke, increasing number of automobiles, property development, and airlines. A research agenda was drawn up with a focus on soliciting feedback from stakeholders about their attitudes on available and future mitigating measures, provision of hotels as pilot test sites, as well as decision-making criteria about IAQ enhancement program. In addition, the study calls for more resources for conducting IAQ-related research and advocates extending the research frontier into the inclusion of IAQ in hotel rating schemes.

Solar photocatalytic degradation of gaseous formaldehyde by sol–gel TiO 2 thin film for enhancement of indoor air quality

Solar photocatalytic degradation of formaldehyde in the gaseous phase has been investigated. The tested photoreactor is made of a borosilicate glass tube with the inner surface coated with a sol–gel TiO 2 thin film. In a pseudo-first-order Langmuir–Hinshelwood (L–H) model, the maximum reaction rate constant obtained is 0.148 min −1 under an exposure to sunlight with solar UVA irradiance of 1.56 mW/cm 2. The solar photolysis effect is found to be negligible. It is also found that the sol–gel TiO 2 thin film has a lower apparent photonic efficiency of solar photocatalysis than a Degussa P25 TiO 2 coating. However, for the photonic efficiency taking into account the absorbed and scattered photons only and, in other words, excluding the transmitted photons, the thin film has a higher value. Based on a total of 28 measured data, an empirical-correlation equation has been developed to express the reactant residue with respect to the solar UVA irradiance and exposure time. A reasonable agreement between the correlation and experimental data is obtained. The findings of this investigation can be applied to design optimization of a honeycomb photoreactor made up of TiO 2-coated glass tubes or polygonal cells.

Heterogeneous Photocatalysis for Control of Volatile Organic Compounds in Indoor Air

Research results concerning the photocatalytic activity and selectivity of benzene are discussed. This compound, which represents one of an important class of volatile organic compounds found in indoor air, was oxidized in an annular photocatalytic reactor featuring a thin film of titanium dioxide and illuminated by a fluorescent black light. The gas phase products, carbon dioxide and carbon monoxide, were quantified with a Fourier transform infrared spectrometer (FTIR). Adsorbed intermediates were extracted from the surface with water. The extract was analyzed via high performance liquid chromatography and some of the adsorbed species were provisionally identified by retention time matching. The adsorption of reactants on the catalyst surface was studied explicitly, particularly with respect to the effect of near-UV radiation on adsorption processes. Maximum and steady-state rates of the surface reactions are reported here as functions of the operating conditions. Deactivation of the catalyst surface is characterized and methods of regeneration of catalyst activity are explored. This established research methodology provides the framework for a broader outline of research into enhancement of indoor air quality via photocatalytic oxidation. The results of investigations are discussed that pertain to a variety of classes of compounds representative of indoor air pollutants.