After more than 1.5 years, the fight against SARS-CoV-2 (COVID-19) continues. No different to the rest of the world, Malaysia has undergone a number of days under lockdown and there is now a consensus that COVID-19 is here to stay. With a high possibility of another pandemic in our lifetime, how can our buildings presently support the fight against COVID-19 but also against future pandemics? When we spend more than 90% of the day inside, how can buildings keep us safe?
In this first of the Indoor Environmental Quality series, we explore how COVID-19 spreads in buildings and what buildings can do to support the fight against COVID-19 and future airborne pandemics.
The following strategies are all established by experts in their respective fields and are referenced in green building certification schemes such as Leadership in Energy and Environmental Design (LEED), WELL and many others.
Fight against the Spread
First, we need to understand how COVID-19 spreads. According to the US Centers for Disease Control and Prevention (CDC), the principal mode of transmission is through exposure to infected respiratory fluids from acts of coughing and sneezing. Respiratory fluids are released in the form of droplets of many sizes which carry the virus. Exposure can occur through three principal ways:
1. Inhalation of air with droplets that are carrying the virus.
Source: Times of India
2. Deposition of virus by being coughed or sneezed on.
Source: India Today
3. Touching contaminated surfaces or droplets and then touching the face.
Now that we understand how COVID-19 primarily spreads, the following recommended strategies can be implemented in building design and operations so that buildings can be made safer.
Improving Indoor Air Quality
In this section, the strategies outlined are to improve the indoor air quality and thus mitigating the risk of inhaling air with infected droplets.
With the emergence of the COVID-19 Delta variant, the need for better indoor air quality is greater than ever due to its high infectiousness.
a. Outdoor Air Supply
The supply of outdoor air indoors is very important to not only purge any virus from the building but also to prevent the build-up of indoor contaminants such as Carbon Dioxide (CO2), Particulate Matter (PM2.5), Volatile Organic Compounds (VOCs) and Formaldehyde. All of which in higher concentrations are harmful to a person’s wellbeing.
It is well documented that a higher ratio of outdoor air indoors would likely result in better indoor air quality which reduces Sick Building Syndrome (SBS) symptoms. A study by Fisk, W., et., 2002. found that offices with a higher rate of outdoor air ventilation compared to the ASHRAE Standard 62.1 had a corresponding 1-2% of increased performance which while small may have significant financial impact. Similarly, a study by Mendell, Eliseeva, et., 2013 found that there was a reduction in absenteeism when there was an increase in outdoor air ventilation.
In a building where there is Air-Conditioning and Mechanical Ventilation (ACMV) system installed, the ASHRAE Standard 62.1 – Ventilation for Acceptable Indoor Air Quality is the industry reference in Malaysia in conjunction with the local code for the specification of minimum outdoor air supply for acceptable indoor air quality. Building designers and operators must take care to ensure that regardless of the ACMV system installed, the minimum outdoor air supply must be met in all occupied spaces for the building’s area and occupancy. Indeed, supplying additional outdoor air than the specified minimum is highly recommended in view of COVID-19.
As for buildings that rely on Natural Ventilation (NV), the ASHRAE Standard 62.1 also provides guidelines to assess the effectiveness of NV for the building. This is important for buildings with deep spaces that are far from windows. Mechanical ventilation assistance may be required to ensure that the air in deeper spaces can be purged.
The illustration below provides an example of the maximum depth from a window for any space depending on the type of openings that space has for effective natural ventilation.
Building designers should also ensure that there are sufficient operable windows installed in the event the ACMV system is inoperable. This will allow the building to be naturally ventilated and prevent disruption to building operations. Following ASHRAE Standard 62.1, the total operable window size should at minimum be 4% of the floor area.
While the supply of outdoor air purges the building of indoor contaminants, filtration is important to ensure that the building occupants breathe in clean air that is free of viruses and other contaminants like VOCs.
In line with ASHRAE’s recommendation, a building’s ACMV system should have at minimum ePM1 70% (MERV 14 / F8) filter installed at all Air Handling Units (AHUs) and Fan Coil Units (FCUs) or the highest-level filtration level for existing systems.
While ASHRAE does not recommend for or against Ultraviolet Germicidal Irradiation (UVGI) in ACMV systems for minimizing the risks of infectious droplets in the air, it is proven that UVGI inactivates microorganisms by damaging its structure. Thus, the usage of UVGI in ACMV systems is to be considered not only for infectious droplets but also for other harmful microorganisms such as mould.
a. Humidity Control
A recent study (Ahlawat, Wiedensohler and Mishra, 2020) have shown that there is a link between Relative Humidity (RH) and the transmissibility of airborne viruses where at lower RH (drier air), the risks of infectious droplets evaporating and being suspended in the air is elevated. The study recommends that the ACMV system controls the indoor air RH between 40 – 60% which earlier studies have shown to be optimal for human health. This is also in line with the Malaysia Standard (MS) 1525:2019 stated RH range of 50 – 70%. The operation of the ACMV system by the building operator is thus crucial in ensuring that the ACMV system is operating per design in reducing the transmissibility of any infected droplets.
While the ACMV system actively controls the indoor air condition, it is also important to apply passive controls by ensuring that the building is air and water tight where possible. Preventing infiltration of humid outdoor air and water.
In this section, the strategies outlined are to ensure the cleanliness of surfaces which prevents our hands from touching contaminated surfaces thus reducing risks of transmission.
Ever since COVID-19 impacted our lives, disinfection has become an everyday norm. However, to date there is still much misunderstanding and misinformation regarding proper disinfection protocols. To prevent the transmission of infectious disease through contaminated surfaces, the following strategies are recommended:
While hand sanitisers have become a part of our daily routine, the CDC recommends hand washing with soap whenever possible instead of using a hand sanitiser as studies have shown that unlike soap and water, hand sanitisers in some instances do not eliminate all types of germs and may not be as effective when hands are dirty/greasy nor remove harmful chemicals.
It is thus recommended that building operators support good handwashing practices by providing the following at all sinks:
Fragrance-free liquid hand soap dispenser
Towels or hand dryer (with HEPA filter)
Signage with proper hand washing steps
Building operators should also take care in the selection of hand soap. The U.S. Food and Drug Administration (FDA) in 2016 banned 19 supposedly antibacterial additives in consumer soaps and body wash as it is not scientifically proven to be beneficial nor more effective than normal soap. Professor Lithgow who is the Director of Monash’s Centre to Impact AMR believes the constant usage of antibacterial soaps can be a significant contributor to the creation of superbugs that are resistant to antibiotics and thus untreatable. Normal soap is sufficient as it works well to loosen the bacteria and viruses off our hands to be washed away easily.
a. Surface Contact
One way to prevent contact with contaminated surfaces is to reduce the need for contact entirely. Building designers and operators should consider hands-free operation for high-touch surfaces such as door handles, elevator buttons, sink taps, and etc.
Hands-free operations can be done through the use of sensor-based automatic doors and sink taps, voice-operated elevators, and etc.
b. Cleaning Operation
It is important that the maintenance of a clean environment does not become a weak link to a building operator’s efforts to prevent the spread of infectious disease. The cleaning crews need to be instructed on a properly developed cleaning plan that details at minimum the following
Extent and frequency of cleaning
Type of cleaning supplies
Surfaces that require disinfection
Record keeping practices
Building operators should take care of the cleaning supplies that are being used. This is to ensure that the cleaning product used does not cause harm to the user or occupants due to the chemical makeup of the product. As a guide, products that are labelled as ‘low-hazard’ or ‘safer’ by an ISO 14024-compliant (Type 1) Ecolabel such as the SIRIM Eco-Labelling scheme and Singapore Green Labelling Scheme (SGLS) or third-party equivalent certification should be used.
In this section, the strategies outlined are to reduce the exposure of infected droplets through deposition by being coughed or sneezed on.
With the onset of the COVID-19 pandemic, physical distancing has been part of our daily lives to reduce the risk of transmission of infectious droplets from the unknowing infected. However, how do we practice physical distancing in the office when it is not designed for it?
As we move forward in a post pandemic world, building designers should consider the applicability of the open office layout. In a study conducted by a team of researchers in Arizona to determine how fast a virus can spread in an open office environment, it was found that within four hours, over 50% of the commonly touched surfaces have been contaminated and by the end of the day, it was 100%.
The close sitting nature of most open office layouts is an ideal environment for the transmissibility of an airborne virus like COVID-19. An investigation by the Korea Centers for Disease Control and Prevention (KCDC) found that in a call centre employing an open office layout with an occupancy density of < 10 m2/person, over 40% of the employees were infected with a majority of the infected all sitting next to each other.
Source: CDC (Floor plan of the call centre. Blue indicating confirmed cases.)
What can a building do to support physical distancing? While an office’s layout is usually outside of the building’s designer’s purview, the building designer can ensure that the common area spaces are sufficient for physical distancing to work. Whereas temporary measures such as barriers and queuing systems can be implemented by the building operator as physical distancing measures in the building. However, care must be taken in the implementation of barriers as it may impede air circulation and cause dead zones where the air is contaminated.
As COVID-19 continues to ravage Malaysia, it is clear that a change in mindset is required for buildings to support the fight against it and any future pandemics. There are building design decisions such as operable windows location, ACMV system design and common area design that needs to be viewed through a different lens. Building owners should ask if their ACMV system is compliant with ASHRAE Standard 62.1 and if there are sufficient windows for effective natural ventilation.
For existing buildings with difficulty in implementing the recommended strategies due to design constraints, building operational strategies such as handwashing support, cleaning operations, and physical distancing should be implemented.
COVID-19 is here to stay and we can no longer continue living and operating in a pre-pandemic world. The recommended strategies should and must be implemented to not just ensure operational continuity but more importantly to ensure the wellbeing of every building occupant.