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A review of air filtration technologies for sustainable and healthy building ventilation
Abstract and Figures
Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation.
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... 4). If humidity levels exceed 50%, the air quality is unsatisfactory (Fang et al., 1998). Poor ventilation, the use of finishes that emit harmful gases such as volatile organic compounds (VOCs), dust accumulation (via outdoor sources or indoor tobacco sources), as well as allergens and airborne fungi can negatively impact IAQ (al horr et al., 2016;G. Liu et al., 2017). ...
... Therefore, using air filters is an important step as it helps remove air pollutants; it is also cost effective as it helps with energy saving (Liu et al., 2020). One review has pointed out that a combination of filtration technologies is needed to provide a sustainable and healthy interior environment (Liu et al., 2017); the reason being that, despite the effectiveness of air filters, they only deal with particulate matter, whereas indoor air pollution includes chemical vapors. In this situation, biofilters such as iVGS may be effective in filtering out VOCs. ...
... Indoor thermal comfort depends on air velocity. A room of constant temperature and devoid of air movement is perceived as uncomfortable and stifling, whereas high air velocities cause discomfort and a sensation of coldness (Liu et al., 2017). High air velocities in buildings can be reduced using green infrastructure (Jaafar et al., 2013;Perini et al., 2011), as well as by using façade treatments. ...
A structure is taken to be a green building if it benefits the environment, people, and the economy. For a building to be ratified as green, the building owners must adhere to specific guidelines and requirements. A green building involves using sustainable practices from construction to completion, as well as having long-term positive effects on users and the environment. Retrofitting vertical greenery offers various benefits, such as increasing indoor air quality, and is an attractive and effective way of achieving green building rating points. This study adopts an integrative review methodology to assess, analyse, and synthesize the current literature, and highlights the potential of green retrofitting for improving indoor environmental quality. The requirements for three green building certification schemes were reviewed and it is concluded that vertical greenery (outdoor and indoor) can potentially contribute to give value/points of the indoor environmental quality rating criteria that are used. The findings also indicate that, vertical greenery is applicable for retrofitting existing or conventional buildings, so they meet green building certification.
... In addition, indoor air quality (IAQ) has received much more attention in recent years in China [19]. Air filters are required to be installed in the heat recovery ventilator or in the fresh air ducts to remove outdoor contaminants [20,21]. Many studies show that these air filters affect the energy consumption of fresh air systems because of pressure drops of air filters. ...
... where, COP H and COP C are the coefficients of performance of the ASHP in the heating season and cooling season, respectively; t a is outdoor fresh air temperature, • C. Therefore, the energy consumed by the constant flow system and baseline system can be calculated according to Eqs. (18) and (19). Energy saving rate of the constant flow system is calculated by Eq. (20). ...
The current demand-based defrosting initiation strategies of air source heat pumps (ASHPs) faces difficulty in achieving a balance between cost and robustness. Therefore, an efficient and innovative demand-based defrosting initiation strategy is proposed in this paper, based on the learned the degradation of heating capacity (DHC) method using data-driven model. Firstly, the DHC method is developed using the initially installed sensors without additional sensors to identify the frosty state. Subsequently, the fully connected neural network (FNN) model is established for predicting frosty state using field measured data from the ASHP system. Finally, the effectiveness of the defrosting initiation strategy is further validated through practical testing. The results demonstrate that the DHC method provides a reliable database for training the FNN model, resulting in an impressive accuracy of 91.43% for predicting the frosty state in the testing set. By adopting the innovative demand-based defrosting initiation strategies, the defrosting frequency, heating loss, and power consumption are respectively decreased by 66.3%, 2.1%, and 6.0% with the SCOP enhanced by 8.6% during a heating season. The promising results highlight that the proposed strategy effectively reduces costs while ensuring the efficiency of demand-based control.
... This could be possible due to the increased surface area of fungal hyphae which could assist bacterial transport through the soil and alteration of root exudates possibly increasing the bioavailability of the compounds and increasing the degradation of the PAH [115]. For the removal of hydrocarbons from soils, the most researched plants are prairie grasses because of their vast fibrous root systems [116]. ...
In recent years, air pollution has become one of the major environmental concerns
that threaten health of the living organisms and its surroundings. Increasing urbanization, industrialization, and other anthropogenic activities impaired the air quality
of indoor and outdoor environment. However, global organizations are focusing on
ecological and biological means of solutions to reduce or eliminate dangerous contaminants from ecosystems in a sustainable manner. In this fact, plants are capable of
improving or cleansing air quality and reduce the concentration of harmful pollutants
from the environment through various remediation processes. Plants interact with air
pollutants and fix them through various biological mechanisms in both associated and
non-associated forms of microbes. In association forms, the mutualistic interaction of
plant and microbes leads to higher growth efficiency of plants and results in enhanced
pollutant degradation in rhizosphere as well as phyllosphere. In this background,
the book chapter provides a comprehensive discussion of the existing literature and
recent advances in phytoremediation process for the mitigation of harmful air pollutants. The role of indoor plants and aids for the enhancement of phytoremediation process towards air pollutants are also discussed.
This paper aims to review the engineering controls for indoor air quality (IAQ) from a systems design perspective. As a result of the review, we classify the literature content into three categories: (1) indoor air treatments, (2) dissemination control strategies, and (3) information technology. Indoor air treatments can be generally interpreted as the “cleaning” aspect, which covers ventilation and contaminant removal techniques. Dissemination control focuses on how contaminants generated in an indoor space can be transmitted, where four types of dissemination are classified. The category of information technology discusses IAQ sensors for monitoring, as well as the applications of the Internet of Things and IAQ data. Then, we further analyze the reviewed engineering controls by performing systems and functional analysis. Along with a discussion of IAQ functions, we suggest some systems design techniques, such as functional decoupling and design for flexibility/resilience, which are expected to promote more systems thinking in designing IAQ solutions.
PURPOSE - Waiting for a bus may represent a period of intense exposure to traffic particles in hot and noisy conditions in the street. To lessen the particle load and tackle heat in bus stops a shelter was equipped with an electrostatic precipitator and a three-step adiabatic cooling system capable of dynamically adjust its operation according to actual conditions. This study evaluates the effectiveness of the Airbitat Oasis Smart Bus Stop, as the shelter was called, to provide clean and cool air. DESIGN/METHODOLOGY/APPROACH - The particle exposure experienced in this innovative shelter was contrasted with that in a conventional shelter located right next to it. Mass concentrations of fine particles and black carbon, and particle number concentration (as a proxy of ultrafine particles) were simultaneously measured in both shelters. Air temperature, relative humidity and noise level were also measured. Findings -
The new shelter did not perform as expected. It only slightly reduced the abundance of fine particles (−6.5%), but not of ultrafine particles and black carbon. Similarly, it reduced air temperature (−1 °C), but increased relative humidity (3%). Its operation did not generate additional noise. PRACTICAL IMPLICATIONS - The shelter's poor performance was presumably due to design flaws induced by a lack of knowledge on traffic particles and fluid dynamics in urban environments. This is an example where harnessing technology without understanding the problem to solve does not work. ORIGINALITY/VALUE - It is uncommon to come across case studies like this one in which the performance and effectiveness of urban infrastructure can be assessed under real-life service settings.
Volatile organic compounds (VOCs) and particulate matter (PM) are both frequently present in air as contaminants, posing serious health and environmental hazards. The current filtration of VOCs utilizes entirely different materials compared with PM filtration, adding complexity to air cleaning system. Herein, we design a pitch-based activated carbon ultrathin fibers (PACUFs) for bifunctional air purification. The PACUFs, with fiber diameter of ∼1.2 µm and specific surface area of 2341 m2 g−1, provide both high VOCs adsorption capacity (∼706 mg g−1) and excellent efficiency of ∼97% PM0.3 filtration with low pressure drop. In contrast, traditional activated carbon fibers exhibit VOCs adsorption capacity of ∼448 mg g−1 and PM0.3 removal efficiency of only ∼36% at an equal area density of ∼190 g m−2. Theoretical investigations reveal the filtration mechanism of the high-performance bifunctional fibrous PACUFs, considering full advantages of the high surface area, small pore size, and significant micropore volume.
To overcome the excessive heat in tropical climate countries during the day, the types of skin or façade play a vital role in regulating the temperature and the amount of heat transmission in a building. This research was carried to evaluate the percentage of temperature reduction of two building samples, one with “vertical greening” and one without. The result proved that the temperature reduction of the building with the green façade system is higher than the building without the green façade system. Therefore, it justifies that Vertical Greening Facade does act as an acceptable passive approach for sustainable design.
The number-one environmental threat to public health, air pollution remains a pressing problem-made even more complicated by the massive quantity and diversity of air pollution sources. Biofiltration technology (using micro-organisms growing on porous media) is being recognized as one of the most advantageous means to convert pollutants to harmless products. Done properly, biofiltration works at a reasonable cost-utilizing inexpensive components, without requiring fuel or generating hazardous by-products. Firmly established in Europe, biofiltration techniques are being increasingly applied in North America: Biofiltration for Air Pollution Control offers the necessary knowledge to "do it right."
This work deals with development, characterization, and application of triboelectrically charged nonwoven electrets. The electrets were prepared using wool and polypropylene fibers and employing needlepunched nonwoven technology. It was observed that the magnitude and duration of electret charge increased with a decrease in diameter of wool and polypropylene fibers. The charge was found to decay double exponentially, presumably due to quick decay of surface charge and slow decay of bulk charge. The charge in tribocharged electrets was utilized to capture hazardous particles from the air stream very efficiently. The electret media exhibited remarkably higher filtration efficiency than the uncharged media.
In this study, a dielectric barrier discharge (DBD) non-thermal plasma experimental set-up is utilized to investigate the effect of design parameters including the configuration and type of electrodes as well as the size of the reactor on the energy consumption and the rate of ozone generation. Results show that increasing the residence time by applying a larger length of the inner electrode causes an earlier plasma ignition, as well as formation of larger amounts of ozone for a given specific input energy (SIE). Changing the configuration and the type of the ground electrode shows that this electrode configuration is a dominant parameter for enhancing the energy yield in the plasma reactor. Furthermore, it was noted as the size of the reactor is increased, by increasing the gap between the electrodes, higher level of SIE is needed to reach the same level of ozone concentration.
Fibrous media is the most common method of filtration, which is generally characterized by its pressure drop and filtration efficiency. In this work, the computational fluid dynamics (CFD) technology was applied to simulate the filtration performance of multi–fiber filters. The pressure drop and filtration efficiency with different fiber arrangements, fiber diameters, face velocities and particle sizes were studied. It was found that filtration efficiency changed with the face velocity for different particle sizes. The layered structures with the same fiber diameters and total solid volume fraction (SVF) were compared, indicating that the dense–sparse structure had the highest filtration efficiency for all the simulated particle sizes at the cost of high pressure drop. Then the dense–sparse structure was optimized to achieve a better filtration performance by using less tiny fibers in the front–row and removing some fibers in the back–row.
Living walls are systems that allow the development of vegetation in a vertical surface attached to building facades or indoor walls. Traditionally, they have behaved as ‘passive’ bio-filters, but new approaches and technologies are moving towards their integration within the building's air conditioning and ventilation systems. In an Active Living Wall (ALW), air is forced to pass through the vegetated wall to take advantage of their evaporative cooling potential as well as the capacity of these biological systems to purify air. In the case of indoor ALWs, air is cooled, bio-filtered and humidified thus potentially reducing ventilation requirements. This work describes a prototypic indoor ALWs installed at the University of Seville (Spain). Preliminary results of its performance on indoor air conditions (temperature and humidity) are presented and discussed. Drops in temperature between 0.8 and 4.8 °C have been observed at different distances from the ALW. The cooling process was more efficient when the initial conditions of the room were drier and warmer.
Background: Storage of fruit, vegetables and other products is used worldwide with a wide variety of foods. In many cases, though environmental conditions such as air humidity and temperature are taken into consideration, air filters are not employed even though such filters could potentially reduce the perishing of product during storage. Scope and approach: The purpose of this review is to list and evaluate currently available air filtration technologies, in order to determine their suitability for use inside food storage warehouses. Factors such as pressure drop, running costs, and the environmental conditions which the filters will be operating in need to be taken into consideration. Key findings and conclusions: A number of physical filters, i.e., HEPA, glass fiber, PTFE and cellulose filters as well as polyurethane foams and nanofiber mats are presented first. These are filters which function by providing a physical barrier which particles cannot pass through, or which particles stick to. These are followed by a discussion of other, non-physical methods, such as electrostatic precipitation, cold plasma, wet scrubbing, cyclonic air filtration, UV radiation (and coatings), fumigation, nanoparticles bound on filter media, which are either commonly employed in industry, or are interesting emerging technologies.
In order to enhance the photocatalytic indoor air purifying efficiency, the photocatalytic technology was combined with non-thermal plasma to improve the removal of indoor air contaminants. The experimental results show that the removal rate of formaldehyde is improved sharply by plasma and photocatalysis. The removal rate of formaldehyde is increased with the increasing of excited voltage for plasma and the removal of contaminants has the maximal value under the optimal excited voltage in this paper. So the combination of photocatalysis with plasma is an applying direction of photocatalytic technology for air purification.
