Eurovent publishes recommendation on air leakages

BRUSSELS, Belgium, 17 February 2021: The Eurovent Product Group, ‘Air Handling Units’ (PG-AHU) published the first edition of Eurovent Recommendation 6/15 – Air Leakages in Air-Handling Units, Eurovent said through a Press release. The Recommendation presents guidelines for improving Indoor Air Quality and correcting the performance of air-handling units due to internal leakages.

Eurovent Recommendation 6/15 is the first comprehensive publication that gives an in-depth overview of the issue of air leakages in Air Handling Units, including:

• Explanation of leakage types
• Reference to related standards and regulations
• Clarification of leakage indicators
• Typical leakage rates for various design options
• Guidance on design, commissioning and maintenance for eliminating or minimising leakages
• Correction of Air-handling unit performance due to internal leakages

Igor Sikonczyk, Secretary of the Eurovent PG-AHU, said: “The fundamental role of mechanical ventilation is to renew polluted indoor air with fresh outdoor air, in order to provide a safe and healthy indoor environment. One of the problems in achieving this objective is air leakage occurring in the duct network and in the air-handling units. Our new Recommendation sets out the principles for good practices to limit air leakages to ultimately improve Indoor Air Quality and reduce energy consumption.”

According to Eurovent, Recommendation 6/15 is addressed to all ventilation and air conditioning professionals, including system planners, installers and manufacturers. The association added that It is available for download free of charge at the Eurovent Document Web Shop.

Kingspan Insulation launches product for external ductwork applications

DUBAI, UAE, 5 January 2021: Kingspan Insulation launched the KDuct, which the company described in a Press release as catering to external ductwork applications.

According to the company, the KDuct incorporates its pre-clad ductwork system, made of thermoset, fibre-free pre-insulated duct board with a heavy-duty outer jacket. The company described the product as ideal for external applications, plantrooms, risers, congested spaces and lightweight specifications. The KDuct, Kingspan claimed, offers high performance, rigid, closed-cell insulation core, manufactured with a blowing agent with zero Ozone Depleting Potential (ODP) and low Global Warming Potential (GWP). At the same time, it said, the panels are faced on both sides with an embossed aluminium foil. The new product line would provide ultra-strength and rigidness; cost-savings over traditional exterior ductwork; extra-low air leakage, which does not allow conditioned air to escape; and high-compressive strength, among several other benefits, the company said.

Sarmad Fakhri, Managing Director, Kingspan Insulation, said, “KDuct Ductwork system would help our customers to save extra cost and time due to its lightweight and single-fix properties.” Unlike the traditional approach to ductwork construction, which requires sections to be lagged with insulation, once installed, the KDuct panels are pre-insulated with a high-performance insulation core, the company said. This single-fix and lightweight design, the company added, reduces installation time and transfers the cost benefits to the building owners.

How to kill enveloped viruses in just 30 minutes

Poor ventilation in closed indoor environments is associated with increased transmission of respiratory infections. There have been numerous SARS-CoV-2 transmission events associated with closed spaces, including some from pre-symptomatic cases. The role of ventilation in preventing SARS-CoV-2 transmission is not well-defined – that is, by preventing dispersal of infectious particles in small waterdrops to minimise the risk of transmission or preventing transfer of an infectious dose to susceptible individuals.

SARS-CoV-2 is thought to be primarily transmitted through large respiratory droplets; however, an increasing number of outbreak reports implicate the role of aerosols in SARS-CoV-2 outbreaks. Aerosols consist of small droplets and droplet nuclei, which remain in the air for longer than large droplets. Studies indicate that SARS-CoV-2 particles can remain infectious on various materials, such as air conditioning surfaces in air ducts and air handlers, as well as in aerosols in indoor environments, with the duration of infectivity depending on temperature and humidity.

While HVAC coatings are often the most cost-efficient insurance for the longevity of your air-handling system, there’s much more to them than just increasing your building systems’ lifespan. The rising demand for antimicrobial coatings was triggered by the COVID-19 pandemic and tenants worried about their wellbeing from airborne diseases. In the same category, antimicrobial coatings can make a huge difference for indoor air quality and occupant safety. There are a number of HVAC coatings that drive energy savings, primarily desiccant-coatings.

Found on AHU heat exchangers, coils and in duct systems, they enable recovering heat and moisture, which then helps building owners to save on operational cost. Recent studies have uncovered an extreme antimicrobial effect of desiccant coating systems, in high relative humidity, as present in air conditioning systems. It appears the surfactants can break the exterior protein of a virus or bacteria strain. Once the protein is destroyed, the virus cannot attach to cells and transfer or alter human ribonucleic acid (RNA).

In many circumstances, once microbes have begun to proliferate on a painted surface, constant cleaning and disinfecting is required to keep growth under control, which is highly unwanted inside an air conditioning system. Recognising that the ability to clean constantly is unreasonable in most air conditioning systems, the best weapon against corrosion and microbial growth is an antimicrobial paint that prevents growth of, or eliminates, bacteria and viruses. Both the coating and the possible active ingredient should not produce any environmental, safety or health issues during application. Any off-gas from the film is unwanted, because ideally, the coating must be applied to air conditioning systems in operation without any concern of release of poisonous additives.

Antimicrobial efficacy based on silver ions

Generally, an antimicrobial surface contains an additive, like Agion, which inhibits the antimicrobial property that is composed primarily of silver ions, which have been proven in antimicrobial use throughout history. It incorporates silver ions inside a zeolite carrier, providing an area for these ions to exchange with other positively charged ions – often sodium – from the moisture in the environment.

Once exchanged, these now “free” silver ions are attracted to oppositely charged hydrogen ions, commonly found in most bacteria and microbes. The bacteria and microbes’ respiration and growth are now abruptly halted, since the hydrogen ions are no longer available. Silver based antimicrobial coatings contain a pesticide additive that evaporates slowly from the coating surface and raises questions on the durability of discharge. In Europe and North America, these coatings require a registration by the government authorities.

Antimicrobial efficacy based on desiccation

Enveloped viruses, like the H1N1 influenza virus, Corona (COVID-19) and bacteria have membranes of protein and enzymes to protect the infecting contents. The spreading of the viruses and bacteria in closed spaces and air conditioning systems is carried out by smaller aerosols. Alternative antimicrobial functionality is based on desiccation, a physical process to extract the moisture from the virus and bacteria particles. This approach may seem relatively primitive; however, it is extremely effective in slowing down or even preventing microbes from spreading and transmission. This method is similar to other physical treatments, such as UV irradiation, filtering and heating.

Desiccant coatings inactivate a wide variety of microbes that adhere to the surface through their hydrophilic surface properties. The antiviral functionality of the coating has been tested on the Phi6 virus, which is commonly used as surrogate for enveloped Corona viruses.

 

 

 

Studies

A recent study shows that a desiccant coating can have an extremely quick kill-rate of enveloped viruses after just 30 minutes.

Further studies have proven that strong antimicrobial working was additionally confirmed. Surface activity results in full kill-rates of > 99,99%, which were confirmed on the following micro-organism strains:

• Salmonella
• Legionella
• E-Coli
• MRSA
• Klebsiella Pneumoniae

 

An important note should be added to this paper: No claim or assertion should be made that the antimicrobial properties in the coating will improve air quality or eliminate the threat of disease-causing microbes in the air supply system. A healthy indoor air system is highly dependent on a combination of design, maintenance and cleaning measurements that are incorporated in the air conditioning system and facility management procedures.

1. Knibbs LD, Morawska L, Bell SC, Grzybowski P. Room ventilation and the risk of airborne infection transmission in 3 health care settings within a large teaching hospital. Am J Infect Control. 2011 Dec;39(10):866-72.
2. Lu J, Gu J, Li K, Xu C, Su W, Lai Z, et al. COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020. Emerg Infect Dis. 2020 Apr 2;26(7).
3. Rothe C, Schunk M, Sothmann P, Bretzel G, Froeschl G, Wallrauch C, et al. Transmission of 2019-nCoV Infection from an Asymptomatic Contact in Germany. N Engl J Med. 2020 Mar 5;382(10):970-1.
4. World Health Organization (WHO). Natural Ventilation for Infection Control in Health-Care Settings. 2009 [updated 4 May 2020].
5. Ong SWX, Tan YK, Chia PY, Lee TH, Ng OT, Wong MSY, et al. Air, surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient. Jama. 2020;323(16):1610-2.
6. Bahl P, Doolan C, de Silva C, Chughtai AA, Bourouiba L, MacIntyre CR. Airborne or droplet precautions for health workers treating COVID-19? The Journal of Infectious Diseases. 2020.
7. Dietz L, Horve PF, Coil DA, Fretz M, Eisen JA, Van Den Wymelenberg K. 2019 Novel Coronavirus (COVID19) Pandemic: Built Environment Considerations To Reduce Transmission. mSystems. 2020 Apr 7;5(2):e00245-20.

8 Evaluation of Phi6 Persistence and Suitability as an Enveloped Virus Surrogate Aquino de Carvalho, Nathalia; Stachler, Elyse N.; Cimabue, Nicole; Bibby, Kyle Environmental Science & Technology (2017), 51 (15), 8692-8700CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)

Recent outbreaks involving enveloped viruses, such as Ebola virus and SARS COVID-2, have raised questions regarding the persistence of enveloped viruses in the water environment. Efforts have been made to find enveloped virus surrogates due to

challenges investigating viruses that require biosafety-level 3 or 4 handling. In this study, the enveloped bacteriophage Phi6 was evaluated as a surrogate for enveloped waterborne viruses. The persistence of Phi6 was tested in aq. conditions chosen based on previously published viral persistence studies. Our results demonstrated that the predicted T90 (time for 90% inactivation) of Phi6 under the 12 evaluated conditions varied from 24 minutes to 117 days depending on temperature, biological activity, and aq. media compn. Phi6 persistence was then compared with persistence values from other enveloped viruses reported in the literature. The apparent suitability of Phi6 as an enveloped virus surrogate was dependent on the temperature and compn. of the media tested. Of evaluated viruses, 33%, including all conditions considered, had T90 values greater than the 95% confidence interval for Phi6. Ultimately, these results highlight the variability of enveloped virus persistence in the environment and the value of working with the virus of interest for environmental persistence studies.

• The use of bacteriophages of the family Cystoviridae as surrogates for H5N1 highly pathogenic avian influenza viruses in persistence and inactivation studies

Adcock, Noreen J.; Rice, Eugene W.; Sivaganesan, Mano; Brown, Justin D.; Stallknecht, David E.; Swayne, David E.

Journal of Environmental Science and Health, Part A: Toxic/Hazardous Substances & Environmental Engineering (2009), 44 (13), 1362-1366CODEN: JATEF9; ISSN:1093-4529. (Taylor & Francis, Inc.)

Two bacteriophages, .vphi.6 and .vphi.8, were investigated as potential surrogates for H5N1 highly pathogenic avian influenza virus in persistence and chlorine inactivation studies in water. In the persistence studies, .vphi.6 and .vphi.8 remained infectious at least as long as the H5N1 viruses at both 17 and 28 degrees C in fresh water, but results varied in salinated water. The bacteriophage .vphi.6 also exhibited a slightly higher chlorine resistance than that of the H5N1 viruses. Based upon these findings, the bacteriophages may have potential for use as surrogates in persistence and inactivation studies in fresh water.

• Systematic Review and Meta-Analysis of the Persistence and Disinfection of Human Coronaviruses and Their Viral Surrogates in Water and Wastewater, Andrea I. Silverman and Alexandria B. Boehm, April 2020

• Determination of the Antiviral Activity of Water-Based Coating for Air Conditioning Applications against phi6 Bacteriophage using a Method Based on ISO 21702:2019, the laboratories of Industrial Microbiological Services Ltd at Pale Lane Hartley Wintney, Hants, RG27 8DH, UK. December 2020

The writer is with Aqua Aero Coatings and may be contacted at wouter@aquaaero.net