Importance of UV-C in HVAC Industry

Importance of UV-C in HVAC Industry
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Importance of UV-C in HVAC Industry
Introduction
There are millions of commercial buildings currently existing in different regions of the world. However, those working within such buildings are subject to be victims of allergies, sick building syndrome alongside various building-related illnesses due to the existing poor quality of indoor air. The Ultraviolet germicidal irradiation (UVGI) within the commercial building’s HVAC system provides one of the efficient ways of ensuring improvement in the air quality that reduces the level of health risks that the occupants are exposed to. However, there are various factors of consideration in the quest to consider the HVAC design of a building. Some of these factors entail the ultimate use of the facility, as well as the overall budget. The overall analysis should consider life cycle costs and the potential influence of the design solutions on the occupants in the future (An et al., 2018).
In this study, commercial building is applicable in referring to the buildings that are more than 1,000 square feet that basically provide half of their space for office work. A good percentage of people spend a significant amount of their time within these buildings with various systems at work such as ventilation, heating, and cooling systems. Such systems make the indoor air quality of prime importance within these environments. The nature of the indoor air quality always impacts the level of productivity and absenteeism, and of course, insurance premiums. There are both negative and positive impacts of UVGI. The reduced quality of the outside air may lead to the accumulation of contaminants indoors, which ultimately contributes to health effects such as building-related illness (BRI) as well as sick building syndrome (SBS). Some of the reasons behind poor air quality include indoor pollution as well as poor design and maintenance of the ventilation system, this makes it important the aspect of improving indoor air quality within commercial buildings that would contribute towards higher levels of productivity within the workforce. In this case, the use of UVGI technology is applicable to improve the quality of the indoor air (Chao-Yun et al., 2017).
Light is considered a crucial part of the electromagnetic spectrum capable of producing radiant energy. The Ultraviolet light spectrum ranges from short to longer wavelengths. In this case, it is important to note that UV light has wavelengths of approximately 350 nanometers and is basically categorized under invisible light. The existence of holes within the ozone layer increases cancer risk due to the presence of additional ultraviolet radiation within the troposphere. The UV has an ionizing effect that proves to be very harmful to body cells. In this case, when dealing with construction activities, there should be proper storage of building materials to avoid exposure to UV radiation (Rodgers & Saputa, 2017).
The level of contamination in HVAC units is widespread and, as discussed above, often leads to building-related diseases such as bacterial or viral infections, asthma, and hypersensitivity pneumonitis. However, only certain UV lights are applicable in the process of air purification. In this case, the UVGI is applicable in the process of eliminating various types of bacteria as well as viruses. The operation of the UVGI light within the UV-C spectrum provides an effective wavelength spectrum that is effective for germicidal purposes.
There are two types of UV light installations for HVAC: coil sterilization and air sterilization. These methods disinfect the air through UV-C light by cycling through the return ducts. The enhancement of the reflective surface within the In-Duct UVC system maximizes UV-C light in all directions ensuring efficiency is maintained. The coil sterilization within the UV-C lamps targets very sensitive alongside the various problem-prone components that include cooling coils, filters as well as condensation pans. Such targets the microbial growth that appears within hidden areas such as fins, grooves, seams, and edges (Eisenlöffel et al., 2019).
Purpose of the Study
The improvement of the quality of indoor air provides some level of economic impact on buildings within different regions. The majority of the people spend 90 of their time indoors, therefore, making it more important, looking at the ways through which indoor air could be improved.
Aims and Objectives
The overall objective of this study will be to determine the importance of UVC through reliable scientific data from testing, especially in circulating air ducts as well as the potential ability of such lights in killing common microbes, therefore, reducing indoor air contamination.
Specific objectives
* To examine the effective maintenance of UVC in the HVAC system
* To identify the various key factors that impact the use of UVC lights within circulating air ducts
* To evaluate the disinfection capacity of UVC System
Literature Review
The extent to which UVGI systems are capable of deactivating cells depends upon various factors such as the intensity of the UV light, the time taken for irradiation, the humidity level, the target organism alongside other factors. In this case, the effective removal of molds and bacteria within the surfaces of cooling coils and drain pans basically require a less intensive source of UV light compared to UVGI deactivation of the particles that flow through the airstream. This is since there is constant irradiation of the surfaces while at the same time particles within air irradiated within a short duration. According to research, approximately 99% of mold reductions and bacteria are reduced on the irradiated surfaces (Matys et al., 2020). In this case, the level of effectiveness of the UV systems as applicable in irradiating microorganisms within flowing air depends highly on the nature of the microorganisms, the velocity of the air, level of humidity as well as the particle sizes, and also the design of the UV system (Rodgers & Saputa, 2017).
There are few published studies on the nature of health benefits derived from the application of UVGI systems within ducts of HVAC systems, especially in facilities that are not related to health-care. The study by Card et al., (2020) that was conducted within three office buildings, whereby the UVGI systems were switched on and off several times while the occupants remained uninformed of the activity. There was an assessment of the work-related acute health symptoms by the use of questionnaires. The results revealed a statistical significance of between 20 to 40% decreases in symptoms during the duration UVGI was in operation. Similarly, another study was conducted within 19 homes, where UVGI systems were installed in HVAC ducts of the 17 homes. These homes had mold-sensitized allergic children (Guo et al., 2020). The systems were designed to irradiate particles in air moving through the ducts and not through the cooling coils. The UVGI systems were replaced at some point with placebo systems that had a blue light. Results show that with the operation of the UVGI systems, there were 30 to 50% statistically significant improvements within several health results. In this case, there was an improvement in the asthma symptoms scores, days with asthma symptoms as well as asthma medication use within only one period of UVGI treatment. However, the measure of the lung system performance registered improvement in both UVGI treatment periods. However, no significant improvements were registered in several other reported symptoms.
The results, as shown, reveal that studies undertaken on health benefits that apply the UVGI systems to produce inconsistent results. At the same time, there have been a few studies undertaken of UVGI in HVAC systems in facilities outside health organizations. In this case, the evidence on the associated potential health benefits is sufficient enough to warrant further research. This is since the application of the UVGI is more likely to reduce various respiratory infections in the event that they are applied within crowded places with fewer opportunities for infection.
A study conducted by Levetin et al., 2001 on the effectiveness of germicidal UV radiation to reduce fungal contamination within the air-handling units shows the effects of UV-C light on contaminated surfaces. This study was undertaken within a four-story building. In this case, the UV-C lamps were installed downstream within the cooling coils of the air handlers on two floors. In comparison, there was no installation of lamps within the air handlers on the remaining two floors. The lamps installed were left in operation for 24 hours during the period of testing. The test results show that germicidal UV irradiation provides one of the effective approaches that reduce the effects of fungal contamination. The application of the UV lamps results in significantly low levels of fungal contamination within the interior of the insulation lining of the study floor as compared to the control floors. Further, the effects of the airborne fundi were found to be lower within the floor with lamps. Therefore, the findings reveal that a sufficient dose of UV-C light could elaborately reduce the levels of microbial growth within stationary surfaces (Atci et al., 2020).
The study by Menzies et al., 2003 on the effects of UV-C lights installed on office ventilation system on employee health attempts to explain if UV germicidal irradiation of drip pans, as well as cooling coil in HVAC, could influence the health of workers in the office building. In this case, three buildings were ventilated mechanically with sealed windows. The UVGI lamps were installed downstream of the filters, humidifier, and heating coil, and they had parabolic reflectors. Also, on the upstream of the cooling coil as well as condensate drain pan. The various lamps provided within each test group were switched on and off at intervals. The results reveal a significant reduction of contamination by bacteria and fungi on the surfaces that were irradiated by the lamps.
Research conducted by Bahnfleth (2013) entailed the installation of sensors for the purposes of temperature collection, airflow, humidity, and a drop in pressure within the HVAC cooling coils before and after the application of UVGI in cleaning microorganisms.
Pigeot-Remy et al. (2013) provide relevant information on the extent to which the UVC reduces the particle concentration of the indoor air installed in the HVAC systems. Some of the important factors include the rate as well as time taken in the flow of air through the system. Also, the efficiency of the filters, as well as particle size, are factors of consideration. The aspect of reducing indoor air contamination is substantial since the level of exposure to particles for those indoors is high, owing to the increased activities of people that generate particles.
Ultraviolet light is considered one of the most powerful disinfectants due to its high energy photons, capable of damaging any genetic material within the microbes. Notably, the genetic material for most microbes is identified as DNA, while that of viruses such as coronavirus is RNA. There has been an assumption on the fact that UV light is applicable in killing SARS-CoV-2. Previous researches show that UV light could potentially kill coronaviruses, however, there is a lack of substantial data on the same (Bahnfleth, 2013). The UV light uses the mechanism of photochemical dissociation to remove air pollutants. The mechanisms operate at a wavelength that ranges between 100 and 1000nm. The process entails absorbing photons through molecules that result in the excitation of the electrons that makes them migrate from lower to higher energy states. Such action destabilizes the photons, resulting in the release of heat and light in the event that molecules return to their original state. The state of exited electrons enables them to break chemical bonds that alter the molecule’s physical and chemical components.
The aspect of eliminating air pollutants by the use of UV-C requires direct photolysis in case the wavelength is less than 290 nm. Shie et al. (2008) assert that the use of UV-C light with shorter wavelengths proves more efficient for the removal of components such as formaldehyde. In this case, the level of efficiency of UVC in removing pollutants is largely determined by the number of factors such as the amount of UV light, the number of UV lamps available in a given environment, and the method applicable for irradiation. The relative humidity, temperature, flow of air alongside air mixing are also crucial factors (Rodgers & Saputa, 2017).
Building Diversity and their Impact on the Microbiomes
There is diversity in buildings differentiated through geographic location alongside the existing climatic conditions. These include aspects such as HVAC system, age and type of the building, the nature of occupancy, the level of expertise of the operations staff and the nature of the ongoing operations as well as maintenance. Notably, buildings change over time, therefore, the differences in the nature of buildings and the way in which elements of the design and operations influence the indoor microbial environment presents a crucial dimension (Bennett et al., 2011). For instance, in the single-family residential apartments, there exist less control over the management of the various sources of microbes. Therefore, the indoor microbiome tends to reflect the activities of the occupants depending on the geographic location as well as seasonal variations. The various mechanical activities, such as plumbing alongside other systems, dictate on the designer’s choice and the condition of the equipment used depends on the owners as well as occupants and prove to be highly variable. However, the control of the presence of microbes in such buildings may primarily call for the use of a range of biocides as well as antibacterial chemicals.
The HVAC system within such residential houses negates the inclusion of outdoor air circulation. In this case, there is a preference to recirculate interior air for the purposes of controlling the temperature. Such circulation takes place under low-efficiency particle infiltration. These buildings are always installed with local exhaust fans within the kitchens as well as bathrooms to remove moisture as well as odor with varying level of effectiveness. Therefore, it makes it easier for ventilation in these buildings to be provided by weather-driven infiltration through unintentional building leakage as well as opened windows depending on the outdoor weather conditions as well as the resident’s choice. The HVAC, as well as outdoor air systems, vary greatly, especially in high-rise residential buildings (Bennett et al., 2011). The delivery of air through the HVAC system depends on the times and nature of the building.
The microbial environments of commercial buildings that include workplaces share various similarities with residential places with also a significant share of differences. In this case, the commercial buildings could be identified with a greater number of occupants that come into contact with shared surfaces which are potential transfer places for microbes. The central HVAC systems within the offices provide particle filtration that has aerosolized liquid water that relates to air conditioning coils as well as the nature of the humidification system. These provide potential sources of microbes that are spread through mechanical ventilation. Further, the rooftop HVAC components exposed to outside water points could easily support the nourishment and growth of the microbes. At the same time, commercial buildings have higher pressure differentials as compared to residential buildings (Bennett et al., 2011).
There are differences in the characteristics of commercial buildings depending on the size of the structure as well as its use. The majority of United States commercial buildings could be said to be small and medium-sized. Such buildings have restaurants, gas stations, office parks, salons, hospitals and clinics. HVAC systems provide the much needed thermal as well as ventilation requirements of the building. These also provide channels of entry of various outdoor bio-aerosols within buildings alongside means through which airborne contaminants circulate within the building. There is a high probability that HVAC system harbor microbial reservoirs, especially in the presence of humid surfaces.
Air is considered as one of the critical means of microbe transportation, especially within the built environment since it makes the connection between medium and what residents inhale or rather absorb through their skin. The various potential sources of microbial communities that encompass microbiome of the built environment that entail both indoor as well as outdoor sources of micro-organisms provide significant means of their distribution. The ultimate impact of the microbes on general human health depends on how they move through the air as a medium of transport within the building. Practically, the ventilation system within most of the commercial buildings is ensured through envelope infiltration as well as mechanical and natural ventilation system. The design of the HVAC system within the commercial offices operates on the maintenance of temperature as well as humidity within a comfortable range to ensure that there is the delivery of outdoor air for ventilation. Notably, the idea of using engineered natural ventilation systems such as thermal chimneys is becoming common in most regions of the world. The aspect of combining strategies of natural and mechanical ventilation helps in achieving energy savings while at the same time maintains a healthy as well as comfortable environment indoors (Chenari et al., 2016).
There is much attention towards the nature of chemistry within the indoor air quality, which reveals key mechanisms that affect the chemical contamination of indoor air. This is since the flow of air within the commercial building is capable of transporting microbes from interior sources. Notably, some of the airflows are established through design while others are unintended and at the same time, paced under control. There exists air leakage through unintentional openings within commercial buildings that provide potential carriage for the bio-aerosols into the offices. The various leaks on the buildings enable considerable entry of outdoor air with tight buildings providing unavoidable infiltration levels. Such leakages result in outdoor ventilation of air that equals low range rates of mechanical ventilation. According to research, ...