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ASHRAE Epidemic Task Force releases updated Building Readiness Guide

ATLANTA, Georgia, 02 February 2021: With the performance of many HVAC systems in buildings still being evaluated, the ASHRAE Epidemic Task Force has updated its reopening guidance for HVAC systems to help mitigate the transmission of SARS-CoV-2, ASHRAE said through a Press release.

“The Building Readiness Guide includes additional information and clarifications to assist designers and commissioning providers in performing pre- or post-occupancy flush calculations to reduce the time and energy to clear spaces of contaminants between occupancy periods,” said Wade Conlan, Lead, ASHRAE Epidemic Task Force Building Readiness team. “New information includes the theory behind the use of equivalent outdoor air supply, method for calculating the performance of filters and air cleaners in series, and filter droplet nuclei efficiency that help evaluate the systems’ ability to flush the building.”

According to ASHRAE, major updates to the building readiness guidance include the following:

  • Pre- or post-flushing strategy methodology: The strategy has been updated to include the use of filter droplet nuclei efficiency, which is the overall efficiency of filter, based on viable virus particle sizes in the air, to assist in determining the impact of the filter on the recirculated air on the equivalent outdoor air. This allows the filter efficiency as a function of particle size, using ASHRAE Standard 52.2 test results, to be estimated based on the expected size distribution of virus-containing particles in the air. This calculation is currently based on Influenza A data and will be updated as peer-reviewed research becomes available for the distribution of particle sizes that contain a viable SARS-CoV-2 virus. Additionally, a chart has been added to help determine the time to achieve 90%, 95% or 99% contaminant reduction, if the equivalent outdoor air changes per hour is known.
  • Flushing time calculator: There is now a link to a view-only Google Sheet that can be downloaded for use, to help determine the available equivalent outdoor air changes and time to perform the flush. This sheet is based on a typical mixed AHU with filters, cooling coil, with potential for in-AHU air cleaner (UVC is noted in the example), and in-room air cleaning devices. Provided efficiencies of MERV-rated filters are based on the performance of over 200 actual filters from MERV 4 through 16, but the tool also allows users to enter custom characteristics for specific filters.
  • The sheet also calculates the filter droplet nuclei efficiency, based on the cited research but allows a user to adjust the anticipated distribution of virus, as desired. It also allows specification of the zone (room) air distribution effectiveness from ASHRAE Standard 62.1 to account for the impact of the HVAC system air delivery method on the degree of mixing. Default calculations assume perfect mixing. Finally, the tool allows for the target air changes to be adjusted if an owner wants to achieve a different per cent removal in lieu of the recommended 95%. 
  • Heating season guidance: The guide now includes data to consider for heating of outdoor air and the potential impact on pre-heat coils in systems.
  • Adjustments to align with Core Recommendations: The Core Recommendations were released in January 2021, and this guidance document needed to be updated to ensure that the information provided aligned with the intent of those recommendations. This included minimum outdoor air supply and filter efficiency requirements and their role in an equivalent outdoor air supply-based risk mitigation strategy.

According to ASHRAE, the guidance still addresses the tactical commissioning and systems analysis needed to develop a Building Readiness Plan, increased filtration, air cleaning strategies, domestic and plumbing water systems, and overall improvements to a system’s ability to mitigate virus transmission.

Building for the “new normal”

As the world continues to grapple with an ever-shifting economic landscape, owing to the COVID-19 pandemic, stakeholders in the building sector across the GCC region have observed how the pandemic has triggered an evaluation and reassessment of priorities. Ashok Jha, Head FM and Retrofit Projects, Universal Voltas, points out that the unprecedented disruption caused by COVID-19 has prompted many organisations to take actions they have been putting off for some time, including launching new digital services and evolving their business models, enabling greater flexibility in their working and implementing cost optimisation measures.

However, Jha says, perhaps the most notable trend would be the move towards a greater number of retrofit projects in the region. “Because of the COVID-19 pandemic, the oil prices plummeted to one of the lowest levels and government revenues went down in the GCC region,” he says. “This has led to reduced spending across all sectors, including new construction, with the current market seeing greater push towards shallow retrofitting, deep retrofitting, energy conservation and reducing the building carbon footprint in the existing buildings to make them more sustainable.” Jha says that since the number of existing buildings in Oman, Kuwait and the UAE is very high compared to new buildings, there was also a need to address the physical deterioration of the buildings, due to functional and economic obsolescence, and to make them more sustainable. “Because of this, there is a surge in demand for the retrofitting of the existing buildings across the GCC region,” he says (see sidebar).

Andrea Di Gregorio, Executive Director, Reem, Ras Al Khaimah Municipality, also believes the region is poised to see a strong pipeline of retrofit projects. “More focus is being put in refurbishing existing buildings, to bring them up-to-speed with the latest best practices in sustainability,” he says. “We see an increase in interest from building owners in retrofit activities, and we expect this interest to further increase throughout 2021 and in the coming years.”

Energy efficiency and sustainability 

Another major driver for retrofits is the move towards energy efficient and sustainable practices, which has long been heralded by experts in the sector. Jha points out that because of the detrimental impact of buildings on the environment, with occupied buildings and the construction sector accounting for 36% of the global energy consumption and nearly 40% of total direct and indirect CO2 emissions according to International Energy Agency (IEA), the UAE has begun to actively transition into smart and sustainable cities, which has turned the focus on the energy efficiency of the buildings, specifically existing ones. 

In addition to its impact on overall sustainability efforts, much of the move can be attributed to growing awareness on return of investment in terms of reduced operational cost. As Jha points out, retrofitting primarily refers to the measures being taken to replace legacy energy and utility systems with new and energy-efficient technologies. “These technologies not only reduce energy consumption and decrease carbon emissions but also lower maintenance costs, improve safety, enhance productivity, boost property valuations and also prolong the useful life of the assets and the building as a whole,” he says. “In a nutshell, we can say that OPEX of the building reduces and the asset value increases. Hence, it is becoming important day by day to retrofit buildings to not only make them more sustainable for the future but also to derive economical value by reducing the operational cost and, in turn, optimise the rentals and make them more lucrative for the tenants.”

Weighing in, Di Gregorio says that sustainable buildings often result in lower life cycle cost of the building itself. “If sustainability features are carefully selected, operational savings – in terms of energy and water usage and equipment maintenance – typically exceed any incremental investments that those features require,” he says. “For this reason, in a perfect market, where developers are able to fairly monetise their investments in higher quality buildings, we would expect for tenants any rent premiums for more sustainable buildings to be exceeded by the value of operational savings.”

Jha adds that as energy prices continue to rise, the relative benefits of energy efficiency will become increasingly important, and this is leading to a huge surge in demand for equipment, such as Smart LED lights and motion sensors, air curtains and FAHUs, energy-efficient AHUs, FCUs or split units and VAV systems. This has also led to greater demand for water usage reduction through the use of low-flow fixtures, sensors, waterless urinals and low-flush WCs, and also for photovoltaic panels on rooftops to generate electricity from the solar power, among other solutions. 

A renewed focus on IAQ 

While the return on investment (ROI) from retrofitting for energy efficiency is becoming clear, stakeholders are hopeful that the new wave of retrofits would also accommodate enhancements of indoor air quality (IAQ), which has been typically overlooked over the past years. Di Gregorio says that he believes this would be the case. “There is increasing interest in IAQ, partly driven by COVID-19 concerns,” he says. “Some awareness and technical barriers are there; nonetheless we foresee development in this area in the future.”

Jha shares a similar opinion. He says: “Fear of pandemic is looming large in the minds of the people, and therefore, while carrying out the retrofitting of their buildings, owners are ensuring that retrofit projects also take into consideration IAQ of the buildings, where people are currently spending more than 90% of their time and also to reduce the chances of contamination through virus, bacteria, moulds and fungi.”

Di Gregorio says there is a lot of focus on safety and security from building owners, particularly in what concerns disinfection of common areas. “This sometimes adds to other measures, like filtration, turning into improved air quality,” he says. Jha adds that some of the measures that building owners are taking include Demand Control Ventilation through C02 sensors, fitting volume control dampers, ultraviolet lamps in AHUs, ultraviolet germicide irradiation and MERV 13/14 filters. He further adds that there has been an increase in the use of humidifiers and dehumidifiers to maintain humidity in the range of 40-60%, where the microbial and fungal growth is minimal.

Jha also says that the majority of the offices are allowing their staff to work from home and that people are spending more than 90% of their time indoors. “This further necessitates that apt measures are taken by the occupants to ensure proper lux levels, ergonomics and IAQ, as these will have a profound impact on their health and wellbeing and, in turn, impact their productivity,” he says. “Hence, there cannot be a better time than now to address the Indoor Environment Quality (IEQ) issues, if any.” Jha says these are the factors driving a lot of investment being done by the property owners in the built-environment to retrofit their buildings to ensure proper IAQ against the traditional retrofit, where emphasis was mainly towards energy efficiency.

Making a case for retrofits 

Keeping in mind the tangible and intangible benefits of retrofitting, Di Gregorio believes there is more than enough evidence to drive building owners to invest in such initiatives. “If building owners are not thinking about retrofits, they definitely should!” he says. “Retrofit projects tend to have very favourable returns. We are observing that for comprehensive retrofits of commercial buildings in Ras Al Khaimah, the payback time is 3-5 years. And the contracting standards that are being adopted often provide forms of guarantees for the investor on those returns.”

Jha, agreeing, says that in spite of the change in the occupancy profile of buildings, property owners must continue to retrofit within the built-environment. “Retrofitting of existing buildings offers tremendous opportunities for improving asset performance in terms of utilities,” he says. “Retrofitting also offers a potential upside in the overall performance of the building through improved energy efficiency, increased staff productivity, reduced maintenance costs, and better thermal comfort.” Jha believes that such key drivers should serve as a motivation and incentive for building owners, who are on the fence about investing in retrofit projects.

A complete 180

In view of the shifting political landscape, how will the new administration affect the country’s commitment to climate change mitigation?

It’s going to be a complete 180 from the [Donald] Trump administration. In [Joe] Biden’s plan, he mentions “a historic investment” in upgrading four million commercial buildings to return almost a quarter of the savings from retrofits to cash-strapped state and local governments. Specifically, it says that he will “mobilize a trained and skilled American workforce to manufacture, install, service and maintain high-efficiency LED lighting, electric appliances, and advanced heating and cooling systems that run cleaner and less costly”. 

Given our focus on energy savings, I think that this will be great for business as well as for building owners. Some suggest that large rebates may be involved to directly incentivise businesses and make it affordable to pursue these upgrades. 

That being said, although the Trump administration was not at all focused on energy conservation, I found that individual building owners and managers were still pursuing these measures during the Trump administration. Most organisations in the US are interested in conserving energy and saving money. With government focus and incentives, it will just accelerate the demand.

In view of COVID-19, do you see a greater uptake of IAQ equipment throughout the country? 

Yes, for sure. However, these things come with a cost, and with COVID destroying the economy, there is going to have to be some kind of funding or incentives given to get these types of retrofits in place. I will give you an example. Two of our clients in the US requested ultraviolet lighting proposals to be retrofitted into their air handlers and FCUs. We put together the proposals and delivered them; however, neither has been approved yet due to the difficulties these buildings are facing financially due to delinquent tenant rent payments and occupancy.

Another interesting fact is that most of these IAQ retrofits are not intended to deliver energy savings. That is another hurdle to getting these projects approved. One last point – and I don’t think this is limited to the US – customers in the UAE have also asked for ultraviolet lighting to be installed, and it is still difficult to get the approval here, for the same reasons mentioned earlier.

Has there been a heavier-than-usual concentration on the air side of things from building owners, tenants and manufacturers?

The EPA has recommended that guidance provided by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) for managing IAQ during the current pandemic be followed. ASHRAE’s statement is as follows: “Transmission of SARS-CoV-2 through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.”

The two solutions we have seen implemented in the buildings we service in the USA are AHU filter upgrades and increasing the intake of outside air into the building. Both of these changes are very effective and relatively easy to implement as well as low cost.

How has the change in occupancy profile thrown everything into a state of chaos in terms of commercial and residential property requirements? Will this be a driving force towards more retrofit projects? 

In terms of energy conservation measures, this has thrown everything into a state of chaos. One, the commercial buildings are hardly occupied, which has led to energy bills dropping dramatically. However, with less occupancy comes less rent, thus less money to invest in retrofit projects. In addition, building owners, who are still looking for energy savings, are hesitant to move forward, because they are not sure if and when tenants will be returning to the buildings, so to be honest, unless it’s a well-funded customer, this could actually slow the conservation efforts.

Residential buildings face the same issue. People are leaving the dense, populated cities, preferring the suburbs right now, leaving residential multi-family buildings unoccupied and no rents being paid. Until we get herd immunity with the vaccine, and people are comfortable returning to the cities to work and live, this will continue to be challenging.

How have these trends potentially influenced building owners? 

As I stated earlier, most building owners are hesitant even if they want to move forward on new projects, given the current situation. However, some forward thinkers, with ability and the confidence that things will return to normal, are taking this time to invest in conservation efforts, so that when the buildings are occupied, they can take advantage of the maximum savings.

Have there been efforts to retrofit among specialised facilities such as healthcare? 

At the moment, it is difficult to even get a meeting with a healthcare facility in the US. They are overwhelmed and have overcapacity with COVID patients and are focused on saving lives before anything else. Their priority right now is the conservation of life.

Has the pandemic finally trained the spotlight on the importance of having a balance between energy efficiency and IAQ? 

I think that yes, people will be investing in IAQ, or at least investigating their options, especially healthcare facilities and the like. However, in my experience, to be honest, it’s a tough sale, unless there’s a Return on Investment (ROI) in the project. Having said that, UV lighting does have some energy-saving benefits, so maybe a combination of IAQ and energy savings should be highlighted to the building owners in the presentation of these retrofit solutions.

Retrofitting in Kuwait, Oman and the UAE

Ashok Jha

COVID-19 has had a significant adverse impact on organisations, people’s health, their livelihoods and the economy at large in the GCC region countries, says Ashok Jha, Head, FM & Retrofit Projects, Universal Voltas LLC. However, Jha is quick to point out that while the duration and severity of COVID-19’s impact on economies and sectors will undoubtedly vary, companies and governments in the GCC region have done well to set in motion a “look ahead, anticipate, innovate and adjust” roadmap, which has led the construction sector to focus on energy optimisation and retrofitting in existing buildings, which is a key to sustainable construction.

 

Oman 

Citing figures from Global Data, a leading data and analytics company, Jha says that Oman’s construction industry contracted sharply in 2020, plummeting by nearly around -10.3%. “The industry is struggling with challenges presented by the COVID-19 outbreak, low oil prices, and the impact of sovereign credit rating downgrades,” he says. Further compounding the downside risks to the outlook for the industry, the Omani Government has had to rationalise spending.”

Jha adds that given the limited prospects for the government to boost investment in infrastructure and other investment projects, a recovery in the construction sector is expected to be very slow. “Global Data currently expects the construction industry to fall further in 2021, with output contracting by -5.8%,” he says. “The fiscal plan by the Oman Government is intended to reduce public debt, increase the state’s reserves, and diversify revenue away from the oil sector.”

Owing to these factors, Jha believes that new construction spend will be very minimal, and more impetus will be on the retrofitting, deep retrofitting, fit-outs and energy performance optimisation in the built-environment in Oman.

Kuwait

Kuwait has faced similar challenges, Jha says, adding that the construction market shrunk in the year 2020 at about -9.5% approximately, as per Global Data. “The construction industry is struggling with the challenges presented by the outbreak of COVID-19, low oil prices and the impact of sovereign credit rating downgrades,” he says. “Because of this, focus is more towards existing buildings in Kuwait.”

Jha adds that within the built-environment in Kuwait, residential buildings constitute around 81%, commercial buildings are 11%, whereas government buildings constitute four per cent; the remaining four per cent includes commercial, industrial, agricultural and services. “Also, Kuwait has one of the highest per capita electricity consumption and carbon footprint globally, which further necessitates the retrofitting of the buildings to make them more sustainable,” he says. “All the above factors, along with the economic strain, is forcing Kuwait to focus on energy conservation, deep retrofitting, retrofitting and fit-outs in the built-environment with a very minimal spending on new construction.”

UAE

Sharing observations on the UAE market, in particular, Jha says that the COVID-19 outbreak, coupled with low oil prices, has led the construction output in the UAE to contract by nearly 4.8% in 2020, but that a rebound is expected in 2021, as per Global Data. “New project opportunities are expected to be minimal in the coming quarters, as the government is consolidating its widening fiscal debt and COVID-19-related force majeure,” he said. “Over the medium- to longer-term, government investment will remain focused on upgrading physical infrastructure and reforming the financing and regulatory environment.”

Jha adds that the UAE has set high targets for building retrofit, which are reflected in the UAE Energy Strategy 2050 and the Dubai Integrated Energy Strategy. “The latter targets an overall 30% reduction in energy and water use by 2030,” he says. “To support this, Etihad ESCO aims to retrofit 30,000 buildings in the next 10 years and generate 1.68TWh energy savings and around 5.64 BIG of water savings by year 2030.”

ASHRAE Learning Institute opens registration for Spring online courses

ATLANTA, Georgia, 8 January 2021: ASHRAE Learning Institute announced that registration is open for its 2021 Spring online instructor-led course series. The 16 online offerings, including eight new courses, run from January through June, the Institute said

 A new course, ‘Reopening Commercial Buildings: Evaluating Your HVAC System’s Readiness to Mitigate the Spread of SARS-CoV-2’, taking place on January 27, will expound the online ASHRAE COVID-19 details for reopening buildings and the Building Readiness Plan for HVAC systems, the Institute said. The course will help reiterate mitigation strategies available and understand specific buildings arrangements, the Institute added.

 The course, ‘Health Impacts of Indoor Air Extraction, Ventilation, and Filtration – Same or Different’, scheduled for February 17, the Institute said, will cover the future design of forced air ventilation systems and the most cost-effective HVAC operational changes and system modifications to improve existing indoor environments in reducing the spread of viruses.

 The course, ‘Hospital HVAC – Infection Mitigation, Comfort, Performance’, scheduled for February 23, will address the role of HVAC systems in helping to reduce Hospital Associated Infections (HAI), explaining airborne versus contact transmission, the Institute said. This course will describe the why and how filtration, air patterns, air changes, dilution, temperature, humidity, UV and pressurization in hospital HVAC can either help or hinder efforts to reduce HAI, the Institute added.

 According to the Institute, the following is the full schedule of online instructor-led course offerings:

January 26: COVID-19 and Buildings: Re-occupation after Lockdown

January 27: Reopening Commercial Buildings: Evaluating Your HVAC System’s Readiness to Mitigate the Spread of SARS-CoV-2

February 17: Health Impacts of Indoor Air Extraction, Ventilation, and Filtration – Same or Different?
February 23: Hospital HVAC – Infection Mitigation, Comfort, Performance
February 24: Evaluating Your HVAC System’s Readiness to Mitigate the Spread of SARS-CoV-2
March 2: Latest in High-Performance Dedicated Outdoor Air Systems
March 4: Humidity Control I: Design Tips and Traps
March 25: Save 40% by Complying with Standard 90.1-2019
April 6: Commercial Building Energy Audits – Part I
April 13: Commercial Building Energy Audits – Part II
April 20: Air-to-Air Energy Recovery Fundamentals
April 22: V in HVAC – What, Why, Where, How, and How Much
May 4: An Introduction to ASHRAE Existing Building Commissioning
May 11: Fundamentals of Ultraviolet Germicidal Irradiation (UVGI) for Air and Surface Disinfection
May 20: Introduction to BACnet
June 1: Principles of Building Commissioning: ASHRAE Guideline 0 and Standard 202
June 8: Powering with Renewable Resources: Thermal Energy Storage

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

Deciphering the dynamics of The Water Hub

Could you highlight how the drought situation drove Emory to develop The Water Hub?

The Water Hub was a concept my colleagues learnt about at a conference approximately 8-9 years ago. At the time, the technology was deployed in Europe but not in the United States. At the time, even Atlanta was going through heavy drought, and so we pursued the technology, which was put through various capital-funding concepts. Initially, a third-party actually funded, maintained and operated the facility. The water extracts were redistributed through the plants, and the contract was eventually signed in 2013, after which the facility came online in early 2015. In addition, the wastewater treated at the plant meets very high cleanliness standards – so much so that the water can be released back into the creek.

The Water Hub meets almost 100% of the water requirements of the campus’ utility systems, including Emory’s chilled water plants and the central campus steam plant, which provide cooling and heating to over 70 buildings. What is the capacity of the District Energy plants?

The Water Hub can clean up to 400,000 gallons of water per day, and we maximise the volume during our summer cooling period. We have around 20,000-25,000 tonnes of cooling capacity, so we are able to make up the cooling capacity with the volume of water.

The Water Hub, as we understand it, provides a low-energy, high-efficiency cleaning process through filtration, circulation through natural earth and plant bioreactors, and exposure to ultraviolet light and chlorination. How much is the energy cost?

In the locale where we are, our water is sent downstream to a very large water treatment plant, where it would be treated, redistributed and then pumped back into the system. Similar to power and when you have energy-redistributed resources, so we have to pump and process close to where the demand is and we don’t have the distribution losses or the energy needed to pump the clean water back to us or to pump the waste down to the treatment plant. So, the numbers aren’t as transparent as we’d like them to be, but we do know that it is saving energy, because we are only pumping it within our campus.

Could you elaborate on the challenges with regard to achieving operational efficiencies?

One of the things we found out early on was that there are a lot of different things in the sanitary waste stream. We found that one of the research departments was dumping animal beddings into the sewer system, and it was creating problems at the pump intakes. As a result, they had to keep cleaning the pumps and pulling them out. We then asked them to compost the animal beddings, which was a better way to dispose them. It has really given us a crude understanding of what’s in the system, and presently we have an issue where they have found baby wipes in the system. This is a major challenge in terms of what’s plugging the intakes. When you are not in the business, you don’t think about these things. We did not anticipate all this, and now we have installed filtering devices on the front end.

How were you able to reduce carbon emissions with regard to water use on campus?

Well, I think it goes back to discharging and reusing our own water. Now, we are not relying on pumping water from a distance. We also installed solar panels at the facility, so they are helping set the electrical use at the water plant.

Joan Kowal, Senior Director, Energy & Utilities, Emory University

Does the water need to be polished before deploying it as makeup water for the campus chilled-water system?

We have polishers at our steam plant, but we don’t have them at our cooling towers. However, we did have to modify our chemical treatment programme at the cooling towers. Modify in the sense that the original chemistry was based on the quality of the water. So, we had to reduce some and add others, while adjusting the menu of chemicals used.

What happens to the blowdown water? Where does it go?

When water is brought to the cooling tower, it rejects the heat from the chilled water system, and as you reject the heat you see a steam mist coming from the top. The evaporation of water causes a concentrated mix of chemicals left in the basin of the cooling tower. When the chemicals concentrate and get to a point that is high, you then have to get the valve and blow down the water. It is then closed and refilled with non-chemically treated water. We operate in 7-8 cycles of blowing down water, which then goes back to the Hub and mingles with the rest of the water. The rest goes back out to a different part of the sanitary system.

What has been the overall response to The Water Hub? Also, are there any additional challenges with regard to odour?

There are people interested who want to replicate what we have. We were very stringent with our developer, when it comes to smell. There shouldn’t be an odour, and it is located right near residential facilities and offices. The technology we use is such that you don’t have the build-up of gases to create the smell.

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