Article

Effectiveness of HVAC Duct Cleaning Procedures in Improving Indoor Air Quality

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Abstract

Indoor air quality has become one of the most serious environmental concerns as an average person spends about 22 hr indoors on a daily basis. The study reported in this article, was conducted to determine the effectiveness of three commercial HVAC (Heating Ventilation Air Conditioning) duct cleaning processes in reducing the level of airborne particulate matter and viable bioaerosols. The three HVAC sanitation processes were: (1) Contact method (use of conventional vacuum cleaning of interior duct surfaces); (2) Air sweep method (use of compressed air to dislodging dirt and debris); (3) Rotary brush method (insertion of a rotary brush into the ductwork to agitate and dislodge the debris). Effectiveness of these sanitation processes was evaluated in terms of airborne particulate and viable bioaerosol concentrations in residential homes. Eight identical homes were selected in the same neighborhood. Two homes were cleaned using each procedure and two were used as controls. It was found that both particle count readings and bioaerosol concentrations were higher when cleaning was being performed than before or after cleaning, which suggests that dirt, debris and other pollutants may become airborne as a result of disturbances caused by the cleaning processes. Particle count readings at 0.3 micron size were found to have increased due to cigarette smoking. Particle counts at 1.0 micron size were reduced due to HVAC duct cleaning. Post-level bioaerosol concentrations, taken two days after cleaning, were found to be lower than the pre-level concentrations suggesting that the cleaning procedures were effective to some extent. Homes cleaned with the Air Sweep procedure showed the highest degree of reduction in bioaerosol concentration among the three procedures investigated.

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... DC has been reported to increase indoor air pollution in several intervention and case studies. In a carefully designed intervention study with control samples from homes without DC, indoor particle concentrations observed in homes during duct cleaning activities exceeded those measured before cleaning (Ahmad et al., 2001). Further, particles concentrations were higher not only during but after cleaning had taken place (Auger, 1994; Ahmad et al., 2001). ...
... In a carefully designed intervention study with control samples from homes without DC, indoor particle concentrations observed in homes during duct cleaning activities exceeded those measured before cleaning (Ahmad et al., 2001). Further, particles concentrations were higher not only during but after cleaning had taken place (Auger, 1994; Ahmad et al., 2001). These suggest that dirt, debris and other pollutants may become airborne as a result of disturbances caused by the cleaning processes. ...
Article
Unlabelled: Ventilation duct cleaning (DC) is widely advocated to provide good indoor air quality (IAQ), health benefits, cost savings, and enhance ventilation system performance. The aim of the present review is to evaluate the scientific evidence as shown in the literature. There is evidence that under normal operating conditions, ventilation ducts can be contaminated with dusts and serve as reservoirs for microbials to proliferate. While controlled experiments noted that contaminants resuspension can elevate exposure levels indoors, no field studies have correlated poor IAQ with duct contamination. Despite high efficiencies of contaminant removal within the ducts during cleaning, reductions for different indoor air pollutants vary widely, where, post-cleaning air pollutants concentrations can be higher than pre-cleaning levels. Further, there are health concerns in the use of biocides, sealants and encapsulants. There is inadequate evidence to show that DC can improve airflow in ducts and reduce energy consumption. Although epidemiological studies indicate suggestive evidence that improperly maintained ducts are associated with higher risks of symptoms among building occupants, this review finds insufficient evidence that DC can alleviate occupant's symptoms. In summary, the need for duct cleanliness has to be properly balanced by the probable generation of indoor pollution resulting from DC and subsequent potential health risks. Practical implications: Existing evidence is insufficient to draw solid conclusions regarding positive impact of duct cleaning on IAQ, health benefits, cost savings and HVAC performance. Maintaining duct cleanliness has to be properly balanced by the probable generation of indoor pollution and potential health risks.
... Cleaning the HVAC unit and duct system regularly is one approach to keep the indoor air quality at an acceptable level. There are three different conventional methods for cleaning air ducts: contact method, air sweeping method, and rotary brush method [1]. Another method involves spraying a volatile liquid containing the antibacterial substance through the duct inlet; as the solvent evaporates, a dry film layer of polymer-supported antibacterial agent forms on the duct walls, preventing the formation of a suitable environment for fungi and bacteria [2]. ...
Article
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In this study, the performance of a novel method where an antibacterial solution is pressurized and sprayed into recirculated air through nozzles, is investigated numerically. This resembles a jet in a crossflow problem where the antibacterial solution mixes with ventilation air and further adheres to the inner surfaces of the duct. The motion of particles dispersed in antibacterial solution is described as the advection of a passive scalar, i. e., temperature, allowing for a single-phase flow solution. The effectiveness of the coating is evaluated by the temperature distribution on the inner surfaces of the duct. Single phase three-dimensional turbulent flow of air at two different temperatures is modeled and the velocity and temperature fields in the ventilation duct were calculated using the commercial code ANSYS Fluent. The numerical model is validated by experiments conducted on a full-scale test rig, in terms of temperature. The numerical calculations were conducted in four series; where the effect of the nozzle arrangement, the jet injection angle, the jet-to-crossflow velocity ratio, and a time-dependent jet velocity profile of a sinusoidal wave form are investigated. The numerical solutions show that the coating is highly inefficient for velocity ratios less than 3.3, and the period of time-varying jet stream has little effect on the coating performance.
... Ventilation systems, just like other technical services, should be accessible for several reasons. Firstly, it is important to regularly change the filters and clean the ductwork, in order to ensure the supply of clean outdoor air [42]. A list of all maintenance tasks and their corresponding frequency can be found in the ASHRAE standard 62.1 [29]. ...
Article
At present many buildings, that are not able to meet the changing needs of owners and users, are demolished before they reach their technical lifespan. To avoid such waste, the construction industry is shifting to adaptable building practices. Comfort systems in buildings that can effectively deal with an adaptable context are critical to the success of this transition. After all, these systems must ensure that the health and comfort of occupants is guaranteed in all possible flexibility scenarios. In practice, comfort systems that provide ventilation strongly adhere to firmly rooted approaches with limited adaptability. Moreover, implementing adaptability does not happen at the conceptual level, but is achieved by oversizing components and incorporating demand control. Alternative ventilation systems that are conceptually more compatible with an adaptable context are rarely even considered. To fill this knowledge gap, this review article identifies and uses various adaptability characteristics of ventilation systems to qualify both contemporary and innovative ventilation systems based on their ability to facilitate a flexible building use. By juxtaposing the systems, the article goes beyond the state-of-the-art and learns from the meta-level rather than individual cases. It is concluded that traditional ventilation strategies do not provide the most appropriate solution for an adaptive context, that bulky ductwork is incompatible with long-term flexible building use, and that specific guidelines for designing adaptable ventilation systems are lacking. Further research should look into this and additionally quantify the environmental and financial benefits of adaptable ventilation systems through life cycle assessment and life cycle cost evaluation.
... Airborne particulate matter, biochemical aerosol and dust concentrations are usually higher during the cleaning and disinfectant activities, although cleaning procedures are generally effective in reducing (but not eliminating) microbial contamination [30]. us, inpatients should not stay in hospital areas during the cleaning procedures and, as Ahmad et al. [61] stated, the cleaning staff should wear protective suits and masks to protect themselves from biochemical contaminated air. ...
Article
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Introduction: Indoor air quality is one the main issues in which governments are focusing. In healing spaces, several research studies are reporting a growing number of data analysis and research works in order to guarantee and prevent health of users and workers. Currently the main investigations are about biological and physical risks; otherwise chemical ones are less investigated. Several countries are carrying out indoor air quality monitoring in those professional workplaces in which chemicals are used but also in some typically indoor (generic) spaces for the building hygiene assessment. The indoor air is affected by several factors that currently are analyzed punctually, without a whole scenario of all the variable performances. The authors have done a systematic review on the current state of the art and knowledge related to chemical pollution in healing spaces and the emerging strategies, supported by scientific literature, for healthy inpatient rooms and their indoor air. Methodology: The systematic review has been done through the analysis of papers from SCOPUS, DOAJ, and PubMed databases. The survey sample considered 483 scientific articles, between 1989 and 2017, and starting the systematic reading and analysis of the abstracts, only 187 scientific papers were selected, and only 96 were accessible. Discussion: Since scientific literature reports very different outputs and results, the resulting work from the survey is divided into specific fields of interest related to construction and finishing materials, installations, components, ventilation systems, processes, etc. Starting from the systematic reading, the paper classifies the factors of indoor air in four macroareas: outdoor air and microclimatic factors (temperature, relative humidity, air velocity, air change, etc.); management activities (management and maintenance activities, ventilation systems, HVAC, cleaning and disinfectant activities, etc.); design factors (room dimensions, furniture, finishing materials, etc.); and human presence and medical activities (users' presence, their health status, and medical activities carried out in inpatient rooms). Conclusion: The systematic review gives rise to a broad scenario on the existing knowledge regarding the indoor air pollution, design, and management strategies for healthy spaces and several emerging topics. Although the aim of the investigation is strictly related to chemical pollution, several considerations from the biological point of view have been listed. The systematic review, supported by the existing scientific literature, becomes a starting point for considering the importance of the topic and to stimulate the knowledge around this field of interest for improving studies, analysis, and simulations.
... Airborne particulate matter, dust and biochemical aerosol concentrations are usually higher during the cleaning and sanitization process, although cleaning procedures are generally effective in reducing (but not eliminating) microbial contamination. Thus, inpatients should not stay in hospital areas during the cleaning/sanitization procedures and the cleaning staff should wear protective suits and masks to protect themselves from biochemically-contaminated air (Ahmad et al. 2001). And this considering that while infrequent cleaning of the exhaust ducts has been documented as a cause of ...
Chapter
The errors in the design, installation and maintenance of an air-conditioning system within a health facility appear to have consequences that are more serious and complex than those that can be generally hypothesized and verified in the case of residential facilities or offices. This is also due to the presence in hospitals of patients with immune system deficiency. The use of a risk matrix can help to evaluate and better manage the HVAC (Heating, Ventilating and Air-Conditioning) system in healthcare facilities, also allowing to answer questions relating the need to clean the air-conditioning systems. In fact, the latter is associated not only with the reduction of microorganisms, but also with the risk of spreading microorganisms and chemical particles in the environment.
... But, some of the building owner was ignoring the duct maintenance since duct monitoring and maintenance are quite expensive. Duct maintenance including duct cleaning is an effective way to maintain the air duct to supply clean air [5] [6]. The building owner can't afford to do the monitoring frequently due to the expensive budget and therefore the IAQ of the building are in question [4]. ...
Conference Paper
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Mechanical robot has been widely used in environmental monitoring. The robot were apply to the air ducting in the Mechanical Ventilation and Air Conditioning System ( MVAC) to show real view inside the ducting. The aim of the mobile robot is to help reach certain places that cannot afford by human especially in the ducting. This paper highlight the third model of Mechanical Robot Ducting (MerDuct) that has been developed and analyze the result obtains by the MerDuct. Abandoned ducting was selected to gather the visual image by MerDuct using in-situ approach method. The result shows the real condition inside the ducting, and rubbish were found in the ducting. The information gathers by MerDuct start from the beginning to the end of the ducting. The visual image captured will be important for pre and post duct cleaning process. This kind of monitoring also will be the guide for maintenance activity to create safe and clean indoor air to the building occupants and building environment.
... It is reported that many compounds emitted during cooking in a house or enclosed space (especially with poor ventilation) can impact human health in various ways [8]. The options to maintain a pleasant IAQ include: masking with air deodorants, natural ventilation, or HVAC (heating, ventilating, and air conditioning) systems, their effectiveness or efficiencies are often not satisfactory [9]. Among the pollutants released during cooking, aldehydes are some of the most potent eye and skin irritants. ...
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Many classes of odorants and volatile organic compounds that are deleterious to our wellbeing can be emitted from diverse cooking activities. Once emitted, they can persist in our living space for varying durations. In this study, various volatile organic compounds released prior to and during the pan frying of fish (mackerel) were analyzed at three different cooking stages (stage 1 = raw (R), stage 2 = well-done (W), and stage 3 = overcooked/charred (O)). Generally, most volatile organic compounds recorded their highest concentration levels at stage 3 (O), e.g., 465 (trimethylamine) and 106 ppb (acetic acid). In contrast, at stage 2 (W), the lowest volatile organic compounds emissions were observed. The overall results of this study confirm that trimethylamine is identified as the strongest odorous compound, especially prior to cooking (stage 1 (R)) and during overcooking leading to charring (stage 3 (O)). As there is a paucity of research effort to measure odor intensities from pan frying of mackerel, this study will provide valuable information regarding the management of indoor air quality.
... The types of air conditioning systems and building age do not significantly influence CO 2 concentration. The effectiveness of air conditioning systems (i.e., maintenance, cleaning procedures, and periodic inspection) improves ventilation and increases the air ventilation measurement level supplied in the indoor environment (Irtishad, 2001). ...
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Universities are designed for higher education learning, and improving university indoor air quality (IAQ) is essential to the enhanced performances of students and staff members alike. The majority of IAQ problems are due to inadequate ventilation in university buildings. Carbon Dioxide (CO2) measurements have become a commonly used as a screening test of IAQ because measurement levels can be used to evaluate the amount of ventilation and general comfort. This paper examines CO2 field measurement for undergraduate practical classes. Ten air conditioned laboratories with ventilation were chosen for CO2 field measurement. CO2 was monitored under indoor and outdoor conditions. Indoor CO2 concentration for Laboratories 1 and 10 is observed to be higher than 1000 ppm which indicated inadequate ventilation, while other laboratories showed CO2 concentrations less than 1000ppm. Air capacity and outdoor air were calculated based on the design documentation. A comparison between design and actual outdoor air/person values indicates that the air conditioning systems of the laboratories had adequate ventilation.
... Diffusers and grills should be placed at opposite ends of buildings and free from any obstructions that may result in the block of air flow in to the building (Foarde and Menetrez 2002). Effective air filtration ensures clean indoor air (Ahmad et al., 2001). Impingement, electronic and adsorption techniques are the three common air filtration technologies designed to get clean air (Escombe et al. 2009). ...
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Indoor environments play important roles in human health. The health hazards posed by polluted indoor environments include allergy, infections and toxicity. Life style changes have resulted in a shift from open air environments to air tight, energy efficient, environments, in which people spend a substantial portion of their time. Most indoor air pollution comes from the hazardous non biological agents and biological agents. Fungi are ubiquitous in distribution and are a serious threat to public health in indoor environments. In this communication, we have reviewed the current status on biotic indoor air pollution, role of fungi as biological contaminants and their impact on human health.
... This comparison has been made and we did not limit our efforts to evaluating only the mycetic load, but also studied the general bacterial load. Since this ventilation equipment naturally faces a certain degree of particulate as well as dust contamination while in use [28,29], numerous systems aimed at decontamination, sanification and disinfection have focused on these aspects [30,31]. Both our ventilation systems have been evaluated immediately after the cleaning operation. ...
Article
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