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As countries around the world battled the COVID-19 outbreak since late 2019, efforts to reopen put churches and schools at the forefront of the fight. Heading into what's hopefully a post-pandemic period, scientists and building systems designers are focusing on the buildings in which we operate, and how they contribute to occupants' wellness, including in-house worshippers at church. While there is much more to learn, the efficacy, simplicity, and low cost of various techniques may surprise both building designers and operators.
When coupled with a structured maintenance program, the risks of a “sick” building can be greatly reduced with better filtering.
What makes church buildings sick?
Even before COVID-19 droplets threatened our health, building systems played an important role in keeping people vital and productive. Studies have shown a significant decrease in absenteeism and depression among workers exposed to clean air and a sustainable, healthy working environment. The term Sick Building Syndrome (SBS) was coined in 1980s by the World Health Organization when reports suggested that an alarming number of occupants of new or renovated buildings worldwide were suffering as the result of being subjected to poor Indoor Air Quality (IAQ).
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has established standards for Air Changes per Hour (ACH) for various environments, including a recommendation of 8 to 15 ACH for auditoriums.
Sick Building Syndrome brought to light that the air quality of indoor spaces can be directly related to various ailments and illnesses. While these were mostly characterized by headaches, respiratory problems, and skin irritations in the past, it’s now clear that buildings that don’t promote good general health by trapping indoor pollutants and micro-organisms, or that have inadequate ventilation, are much more likely to play a role in the spread of transmissible airborne diseases.
Studies of "sick" buildings have indicated four primary sources of trouble:
- Chemical Contaminants -- These can be outdoor chemical contaminants, such as vehicle exhaust that can be introduced through the air intakes, as well as indoor chemical contaminants such as Volatile Organic Compounds (VOCs) from cleaning agents, dry cleaning fluid, paints, lacquers, or adhesives. VOCs can even come from personal care products such as perfume and hair spray.
- Biological Contaminants – Bacteria, molds, pollen, and viruses are typical biological hazards that can breed in stagnant waters located in drain pipes, ducts, and humidifiers. As we’ve seen with COVID-19 droplet studies, the spread of airborne viruses in large buildings can occur very quickly and affect numerous occupants. Before COVID-19, many will recall instances of building-related Legionnaires' disease in Philadelphia and Quebec City.
- Inadequate Ventilation – The standards for adequate ventilation for office and commercial buildings have evolved in recent years. Studies in this area have highlighted the importance of proper ventilation in all environments. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has established standards for Air Changes per Hour (ACH) for various environments, including a recommendation of 8 to 15 ACH for auditoriums.
- Filtration Efficiency – Proper filter selection and maintenance in any environment is a key factor in optimizing a clean air environment and controlling energy costs. High-efficiency filters can provide higher filtration efficiency at a very low initial resistance. When coupled with a structured maintenance program, the risks of a “sick” building can be greatly reduced with better filtering. A Minimum Efficiency Reporting Value (MERV) rating system provides an indication as to how filters will reduce particle counts. For example, changing out a pleated filter rated at MERV 8 with a MERV 13 pleated filter will allow for a greatly reduced particle count at smaller particulate levels and make for a healthier environment. The MERV ratings go from 1 to 20 with popular HEPA filters being some of the highest rated, between 17 and 20, but depending on their design, not all HVAC systems can support filters with a high MERV rating, and just how much protection against particles and droplets of relevant size is still debatable.
Focusing on biological enemies
In a 2020 interview with CNN, Harvard environmental health researcher Joseph Gardner Allen reflected on how building awareness and action to promote healthy buildings can fight airborne disease. "I've been writing consistently ... about how healthy buildings should be the first line of defense against the novel coronavirus," says Allen, who directs the Healthy Buildings program at the Harvard T.H. Chan School of Public Health. He believes that taking steps to keep your environment healthy, including proper ventilation and filtration, should be included with advice about hand washing, maintaining social distancing, and other basic protection measures. In short, Allen believes in a prudent and pragmatic approach.
In early May 2020, Allen and Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, co-published research focusing specifically on the role that smaller airborne particles played in the spread of the novel coronavirus. The research showed that it is impossible for someone to release "large droplets" (>5 microns) without also releasing smaller ones. Thus, transmission that is purported to occur via the spray of large droplets from a cough could, in fact, be occurring through inhalation of much smaller droplets at close range. Marr, whose previous discovery that the flu virus could float in the air in microscopic droplets for an hour or more, finds that likening how small droplets travel to cigarette smoke provides an accurate visualization of how viruses spread.
Marr maintains that, like cigarette smoke, the smaller microscopic droplets (aerosols) are going to be more concentrated closer to the smoker, as COVID droplets would be to the person who might be infected. The farther away you get, your exposure lessens greatly. Knowing how droplets travel provides clues as to how best to predict their movement indoors.
The cigarette smoke analogy has not been lost on Steve Hugo, principal at HOLT Architects of Ithaca, New York. His firm and colleagues at M/E Engineering of Syracuse, New York used Computational Fluid Dynamic (CFD) software to create simulations, adapting the technology from its primary use (modeling the spread of smoke particles), to study the spread of a virus. A series of simulations modeled the spread of contaminated droplets through the company’s offices with examples of one person coughing three times over the course of 10 minutes, with and without a mask.
Cough simulation courtesy of HOLT Architects.
HOLT’s simulations showed how the droplets that escape can propagate dramatically and linger in an enclosed space ... The study is a dramatic illustration of why an appropriate and functioning HVAC design is needed to provide effective air exchange and filtering.
HOLT’s simulations showed that the droplets that escape can propagate dramatically and linger in an enclosed space. “In an enclosed space, a mask and six feet might offer a false sense of security,” notes Hugo. The study is a dramatic illustration of why an appropriate and functioning HVAC design is needed to provide effective air exchange and filtering. The simulations, made available on the company's YouTube channel, illustrate a number of other issues, including how far droplets travel, where they tend to linger, and how the placement of returns can impact the effective exchange of air.
Healthy solutions
While there is no doubt that COVID-19 bumped up interest levels for Ultra-Violet (UV) lights (already regularly used in hospital and research facilities), manufacturers are not yet making claims that more newly recognized UV-C (UV light that can disrupt the DNA of some viruses, thus sterilizing them) is a solid defense against viruses.
Columbia University’s website highlights the institution's research efforts with UV-C, demonstrating effectiveness in killing two coronaviruses that inflict less severe symptoms on humans than COVID-19. The university is now conducting similar testing against the novel coronavirus. In addition, ASHRAE offers a broad statement that UV-C light is a disease-fighter, issuing guidance recommending it as part of an overall clean air strategy.
It is important to note that not all suggestions from HVAC experts to battle viruses, such as COVID-19, are complex or costly to implement. As HOLT’s simulations indicate, some of the most prudent advice to reduce the risk of virus transmission includes compartmentalization of space to minimize exposure and working with an HVAC specialist to increase the number of regular air changes in a building, along with simply finding ways of diluting the indoor air.
Virtually all modern air conditioning systems in commercial buildings have a process called “makeup air” where they take in air from outside, condition it, and bring it inside. Opening dampers to increase the amount of makeup air may not be ideal in regards to energy costs, but the more outside air brought in, the more dilution of any potential virus and the safer occupants are.
Some of the most prudent advice to reduce the risk of virus transmission includes compartmentalization of space to minimize exposure and working with an HVAC specialist to increase the number of regular air changes in a building, along with simply finding ways to dilute the indoor air.
To sum up, church designers, church leaders, and building managers are likely to embrace these commonly recommended solutions in the treatment and prevention of Sick Building Syndrome:
- Routine maintenance of HVAC systems that treats the building as a whole and includes periodic cleaning or replacement of filters
- Selection of alternative air filters with the highest possible efficiency, while maintaining a low pressure drop (resistance to air flow)
- Increasing ventilation rates and air distribution
The editors of Church.Design would like to know your thoughts on building safety and what measures you're implementing in the churches you design, operate, and in which you worship. Share your experiences and ideas in the comments section below.
