Using Building Science to prevent the spread of COVID-19

Managing a building was never easy, but now during the COVID-19 pandemic, you are faced with a new challenge. You must now learn how to operate your building more effectively to prevent any virus or airborne contaminants. Where do you even begin?

Keller Jansen Engineers are building experts who have evaluated over 750,000 buildings across the U.S. and Canada. We are part of a well-established business franchise and have been in the business for more than 60 years! We have compiled research and information to help building owners and managers learn more about this subject as they prepare to open buildings to employees and the general public.

This article will discuss building opportunities, indoor air quality improvement, air dilution & filtration, and much more!

At the end of this article, we have compiled a list of recommendations for building owners from our engineers at Keller Jansen, so keep reading!

Non-HVAC Actions or Buildings that Remain Open

From information provided by the World Health Organization (WHO), we know that the Coronavirus can be transmitted through inanimate objects like doorknobs. The key here is to increase the disinfection of frequently touched surfaces and install more hand sanitation dispensers.

If you have a communal coffee machine or food preparation station, you should consider these two options:

1. Supervision of the area.
2. Completely shut down areas where there is a chance of contamination.

Heating, ventilation, and air conditioning (HVAC) are required

There are many forms of transmission of the COVID-19 virus. One form of transmission is when particles, also known as aerosols, behave more like gas and can travel through the air for longer distances, which results in transmitting to people and settling on surfaces.

To combat these aerosols, it is advised to increase outdoor air ventilation. With a decreased population in the building, this increases the effective dilution ventilation per person.

Another tip would be to disable demand-controlled ventilation (DCV) and open minimum outdoor air dampers. In more extreme weather, this becomes more difficult but can be used in mild weather conditions.

Ventilation

Since we are aware that simply talking and breathing can also release droplets and particles, which could result in the further spread of the coronavirus, we need to put precautions in place.

Some ventilation precautions include:

1. Non-aspirating diffusers for unidirectional low-velocity airflow is essential in several settings, including operating rooms.
2. Room pressure differentials are important for controlling airflow between areas in a building. For example, airborne infection isolation rooms (AIIRs) are kept at a negative pressure with respect to the surrounding areas to keep potential infectious agents within the rooms. Some designs for AIIRs incorporate supplemental dilution or exhaust/capture ventilation (CDC 2005).
3. A highly efficient particle filtration to central ventilation systems is likely to reduce the airborne load of infectious particles. This control strategy can reduce the transport of infectious agents within individual areas and from one area to another when they share the same central ventilation system.

Ultraviolet germicidal irradiation

Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (ultraviolet C or UV-C) light to kill or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions.

There are two UVGI strategies for general application:

1. Installation into air handlers and ventilating ducts.
2. Irradiation of the upper air zones of occupied spaces with shielding of the lower occupied areas because UV is harmful to room occupants (Reed 2010). Two strategies used in some but not all health-care occupancies are in-room irradiation of unoccupied spaces and occupied spaces (e.g., operating suites)

Temperature and Humidity

Many HVAC systems can control indoor humidity and temperature, which can influence the transmissibility of infectious agents.

According to Memarzadeh (2011), in a review of 120 papers conducted on the effectiveness of humidity and temperature on the transmission of infectious viruses, numerous researchers suggest that three mechanisms could explain relative humidity (RH’s) observed influence on transmission.

1. Slower evaporation from large droplets influenced by higher humidity that a lower humidity would more rapidly change them into droplet nuclei.
2. RH may act at the level of the host. Breathing dry air could cause desiccation of the nasal mucosa, which would render the host more susceptible to respiratory virus infections.
3. RH may act at the level of the virus particle to affect its virulence.

Although the weight of evidence at this time suggests that controlling RH can reduce transmission of certain airborne infectious organisms, including some strains of influenza, the ASHRAE PD refrains from making a universal recommendation.

Keller Jansen Engineers’ Advice to Building Owners

At the building level, engineers may provide support by:

1. Identifying vulnerabilities with air intake, wind direction, shielding, etc.
2. Identifying building systems and safe zones in the general building
   environment.
3. Identifying approaches to interrupting air supply to designated “shelter-in-place” locations in general building environments.
4. Identifying cohort possibilities for pandemic situations so that all hospital areas may be placed under isolation and negative pressure.

Practical Recommendations Ventilation

Increase air supply and ventilation by:

1. Extending operation of mechanical ventilation systems (change clock times)
2. Changing CO2 ventilation control setpoint to lower than 400ppm value.
3. Keeping ventilation on 24/7 at reduced speed.
4. Keeping exhaust ventilation systems of toilets on 24/7 and making sure underpressure is created in bathrooms.

Natural Ventilation Recommendations

Use more window airing:

1. Suggest opening windows for 15 minutes when entering a room.
2. Do not open windows in toilets with a passive stack or mechanical exhaust systems to infiltrate into other rooms.

Room Air Cleaners Recommendations

• Air cleaners need to have at least HEPA filter efficiency.
• Because the airflow through air cleaners is limited, they can effectively serve usually small rooms.
• Filters should be located in the breathing zone.

Take Steps to Safeguard your Building

Now is the time to ensure the building or buildings you are managing are optimized for safety. If not, the backlash you may face could be detrimental to your career. To provide a safe building, you must fully understand the knowledge and preparation for building science and safety.

Contact the building science experts at Keller Engineering to get the guidance you need to ensure you are doing your part to ensure COVID-19 safety.

Contact Us Today!