Returning to Work and COVID-19: How to Create a Safe Work Environment
By Ryan Thomson, PE – By now, we have all adjusted to the new normal of working from home to help keep our communities safe. But what happens when we eventually return to the office? What can building owners do to continue to keep their employees safe?
While we have been social distancing and staying home, our office buildings have also gone through some changes. Plumbing systems have had little to no demand, our HVAC systems have been running in unoccupied modes with no ventilation air, and our maintenance schedules have probably been put on hold. This building inactivity could amplify the spread of bacteria and viruses.
Studies now point to SARS-CoV-2 as “sufficiently likely” to be passed through airborne transmission. This means that the virus can be passed through droplets in the air typically from sneezing, coughing, toilet flushing, and talking. Ventilation, filtration, and your building ductwork and piping systems have the potential to limit airborne pathogen transmission and help make your building safer.
So, what can you do to ensure everyone continues to be safe through your reopening? Here are a few recommended steps:
Steps to Take Prior to Reopening
Step 1 – Prior to returning to work, ensure your plumbing and HVAC systems go through a process called “building flushing.” Much like having the radiator flushed in your car to clean out debris and provide new fluids, your building can go through a similar process.
For your plumbing systems, start with your cold-water piping. This includes flushing all your water closets and letting your sinks and showers run for a minimum of five minutes.
For your hot water system, circulate your water at operating temperatures (140 deg F for at least 30 mins) to remove and kill off any bacteria that may have settled into your system.
Your HVAC system should be flushed as well to remove dust and contaminants. To do this, set your outdoor air damper positions and all exhaust fans to design occupied setpoints or economizer mode, if available. Run the system for at least two hours to ensure proper air changes are needed to remove all contaminants from the air streams. Take necessary precautions when flushing your building which includes wearing PPE to avoid any contact with bacteria or pathogens that may be released into the environment during the flushing process.
Step 2 – Once the building flush has taken place, look at your HVAC filters. We recommend that the filters be replaced prior to returning to work. This should be done by a licensed contractor experienced with contaminated filter removal and disposal. Consider upgrading your filter Minimum Efficiency Reporting Value (MERV) rating. Read our post on indoor air environments for more information on the MERV rating.
Also consider sealing the edges of the filter banks to eliminate any air bypass, which is recommended by ASHRAE. Be sure your equipment can handle the higher pressure drop prior to any filtration upgrades.
Step 3 – Finally, consider increasing your air exchange rates by increasing the amount of outdoor air and exhaust to and from the building. Be sure to contact your design team to ensure your equipment is properly sized for the increased ventilation load. While you’re adjusting your ventilation, now would be a good time to check your air system balancing and building pressures. In a properly balanced building, airflow should be moving away from the occupants and back to the air handler or out of the building. Consider working with your design team and a licensed Test and Balance contractor to make the proper adjustments.
To demonstrate how important proper airflow circulation and air change rates are to a building, I’ve included this video. The first example is only recirculating air within the space which is what you’d typically see when a building is in an unoccupied mode and not introducing any fresh air. The other is introducing outdoor air to the space and then exhausting it to the outdoors. The video stresses the importance of outdoor ventilation in a building.
Safe and Healthy Workspaces
Your workplace can be made to provide a safe environment for workers returning from working at home. But there are precautions to take—such as proper surface sanitation and handwashing protocols—to prepare your work environment for returning workers. Those should be taken up separately with your human resources and operations leadership. But by following the steps above, along with guidelines set forth by the CDC, WHO, and ASHRAE, you will be moving in the right direction to provide such an environment.
For more information or to walk through this process firsthand, please contact me at firstname.lastname@example.org or 406-237-1261.
Ryan Thomson, PE is a mechanical engineer who manages the mechanical group in Morrison Maierle’s Billings, Montana office. He specializes in HVAC and plumbing design for commercial, healthcare, and education buildings. During his spare time, you can find him at a lake fishing with his two boys.
Technical review of this article provided by Lukash Pruss, PE