Back To Normal: How to prepare your building for a post-coronavirus world
Many of us have just experienced the most unusual month of our lives. Schools have closed, many workers are dealing with lay-offs and furloughs, much of the remaining workforce are working from home, and no one has answers about the future of the economy. The COVID-19 pandemic has had an impact on each of us (some more than others), but it appears we are beginning to see the light at the end of the tunnel.
Due to the method of infection, this virus will have a lasting impact on restaurants, event venues, religious organizations, schools and universities, open offices, and businesses that center around public assembly. The people of the country will be slow to reassemble. They will need reassurance that precautions are being taken to protect their health and the health of their loved ones. Beyond the fundamentals of sanitizing surfaces, washing hands regularly, and screening staff, what else can we do to assure patrons and employees that we have done everything possible to keep the air clean for their health and safety?
Recently, the Centers for Disease Control and Prevention (CDC) and the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE) have released statements acknowledging “changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.” Let’s take a look at some of the strategies building owners and business leaders can implement to fight the spread of disease in their facilities.
1. Increase Ventilation
Flushing the space with outside air will help dilute the indoor air and reduce the likelihood of spreading infection. If your ventilation system is provided with demand-controlled ventilation so that more outside air is provided as more people enter the space, it may be a good idea to temporarily override the demand-controlled ventilation so that more fresh air is supplied. Be careful not to introduce too much outside air, because the temperature and humidity control capabilities of your existing HVAC system may be negatively affected (see strategy #4 below).
2. Install Air Treatment Systems
Air treatment devices using bipolar ionization will be helpful in reducing harmful bacteria and viruses and increasing the effectiveness of existing filtration. It works by producing positive and negatively charged particles that stick to other particles and droplets in the air. The airborne particles stick together in larger groups so that filters are more likely to capture them. There is 3rd party testing for some bipolar ionization products to show that ionization will effectively ‘kill’ or inactivate multiple strains of bacteria and viruses in the space.
3. Improve Filtration
Good filtration is key, especially considering the virus causes respiratory illnesses to spread through droplets in the air. Increasing filter effectiveness rating to at least MERV 13 will help limit transmission of virus carrying aerosols through air distribution ductwork. Be aware that installing more effective filtration could result in reduced HVAC airflow if we’re not careful. If possible, provide at least 2” thick pleated filters. These filters have a larger surface area so the filter pressure drop becomes negligible. When MERV 13 filters are installed in conjunction with bipolar ionization air treatment systems (strategy #2), the filtration effectiveness will be increased to near HEPA filtration levels without sacrificing HVAC fan performance.
4. Maintain Recommended Humidity Ranges
Relative humidity (RH) levels in indoor spaces have been shown to have a direct correlation on the spread of viruses (available here). To reduce transmission rates, relative humidity should be maintained between 40-60%. At this optimal range, infected aerosols settle out of the air more quickly so they can be wiped away. Viruses and bacteria are less infectious when RH is in the optimum zone, and our immune systems are better able to fight infections at these midrange RH levels. Relative humidity in buildings can be controlled with dedicated humidifiers and dehumidifiers. Alternatively, existing building equipment with dehumidification controls may need setpoints lowered to provide humidity levels in the center of the optimum zone at 50%RH.
The response of the HVAC community will be integral to helping businesses and organizations prepare facilities for a post-coronavirus world. This is a great time to be proactive in limiting the further spread of COVID-19. Schedule a time to meet with engineering professionals and HVAC contractors to review your existing building systems, explore ways to increase ventilation rates and filtration effectiveness, and implement those recommendations.
Business leaders will need to make it clear to the public that their venues are safe and steps have been taken to protect the health of everyone involved. If you have questions about your specific facility, please don’t hesitate to contact Method Engineering Group for a full evaluation of your HVAC system.
Andrew McKeever, PE, LEED AP BD+C
Principal, Method Engineering Group
To read the full ASHRAE Position Document on Infectious Aerosols, click here.
To read the full CDC Interim Guidance for COVID-19, click here.
Link to research article, Low ambient humidity impairs barrier function and innate resistance against influenza infection, is available here.