Based on sound science, we are collectively practicing physical distancing to save lives, limit the spread of COVID-19 (SARS-CoV-2 virus), and buy time for the development of vaccines and therapeutics. We have all been making voluntary or involuntary sacrifices for the greater good; some of us by working from home, while others are losing their livelihoods, and still more are potentially risking their lives to provide essential services. As we look forward to finding a new, post-pandemic normal, we will need to rely on sound science to tell us when, and more importantly how, to return to work, school and recreation as safely as possible. Fortunately, there is a wealth of guidance based on established and emerging research on contagions in general and COVID-19 specifically.
Infection Risk Reduction in Buildings
Based on recommendations from OSHA, CDC, ASHRAE and other sources, we can derive best practices, beyond masks and hand washing, to reduce pathogen transmission and infection risks in the places we work, study, play and live. These measures not only reduce serious risks of COVID-19 while we wait for a vaccine, they will also diminish the disruptions caused by seasonal flu and the common cold. Let’s review some of the most impactful strategies.
Planning and Education
A core part of a successful wellness and infection control strategy for business and other organizations is preparedness and education. Resilience planning is not just for hazard events like hurricanes and earthquakes, it also applies to pandemics and economic shocks. A comprehensive plan will include ongoing facility management practices to reduce infection risks, a response plan in case an occupant presents symptoms of serious illness, and policies for sick leave and remote work. Education and ongoing reinforcement are also important, just as it was for habituation of safety practices in construction and manufacturing. Healthy behaviors training for all staff, and specialized training and reinforcement for custodial, food service and other key staff are important risk reduction strategies.
Indoor Environmental Quality
While COVID-19 is new enough that we are still discovering its unique properties, early evidence suggests significant similarities to other more studied pathogens. ASHRAE has compiled decades of research in its Position Document on Airborne Infectious Disease. This compilation, as well as other engineering resources, suggests that dilution ventilation, higher efficiency filtration, UV sanitization and other measures are all effective at reducing airborne transmission risks.
Effective ventilation—Many studies have identified the health benefits of increased fresh air ventilation, including a recent study by Harvard T.H. Chan School of Public Health showing significant increases in cognitive function with higher ventilation rates. Evidence also suggests that this dilution ventilation reduces person-to-person virus transmission risks, meaning that effective ventilation has a direct health and productivity benefit during the pandemic and beyond. The LEED Enhanced Indoor Quality Strategies credit threshold of increased ventilation 30% above the ASHRAE 62.1-2016 minimum requirements is a reasonable threshold to target.
Enhanced filtration—The current understanding of SARS-CoV-2 is that larger respiratory droplets that quickly precipitate to adjacent surfaces are the primary means of transmission. However, there is strong evidence that smaller aerosolized particles can carry the virus through the air for an extended period and potentially recirculate through ventilation systems. In most facilities, a MERV 13 filter may help to capture these particles, while high-risk facilities should consider HEPA filters for greater assurance. However, these filter upgrades may not be practical in many facilities. In these cases, appropriately sized, strategically placed room air cleaners can provide a similar benefit.
Ultraviolet disinfection—Germicidal ultraviolet (GUV) or ultraviolet germicidal irradiation (UVGI), the shortwave range of the UV light spectrum (UV-C), has been shown effective in deactivating viruses. This UVGI technology can be deployed in several ways, including UV sanitizers in air handling equipment or ducts, and upper-room UVGI. Installation in the ventilation system is a practical centralized solution, but air circulation rates may limit its effectiveness. Upper-room UVGI is deployed similar to indirect lighting, typically wall mounted or ceiling suspended above occupant’s heads, with the UV light safely directed upward to irradiate airborne particles exiting air diffusers, entering return grilles, and circulating in convection currents.
Other measures, such as temporarily disabling heat wheels in energy recovery ventilators or overriding demand control ventilation setbacks, may also have some infection risk reduction benefit. Unfortunately, some of these measures may undermine energy efficiency goals in a facility. These energy impacts should be considered, and appropriate mitigation measures taken to offset energy use increases. Research shows that maintaining relative humidity between 40 and 60 percent creates the least hospitable environment for viruses, so controlling humidity is another potential strategy.
Contact Transmission Reduction
Fomites are objects or surfaces that may carry infection. The fomites of greatest concern are high-touch surfaces, such as door pulls, light switches and handrails, that can be a primary means of contact transmission. Increasing the frequency and rigor of high-touch surface cleaning is part of the solution but reducing the number of these surfaces that occupants must touch is perhaps more important. Adding foot pulls on doors, installing automatic openers on high-traffic doors, and retrofitting restrooms with touchless fixtures are all effective measures. Reconfiguring interior spaces to allow physical distancing between occupants will also reduce direct transmission risks. This will require thoughtful design to retain the function and character of these spaces while maintaining separation.
My clients are concerned about the health and wellbeing of their employees and are asking what they can do to keep them as safe as possible. You probably have similar concerns for your staff, customers and other stakeholders. While there is no way to guarantee that occupants won’t get sick if an infected person enters a facility, it is nice to know that there are practical, science-based measures that building owners and managers can take to reduce risks, while also improving the general health and wellness of building occupants. The specific solutions may vary, but sound guidance is available on the most effective approaches to consider.
Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect with over 30 years of experience in sustainable building design. He is a senior consultant with Intertek Building Science Solutions in Portland, Ore. To learn more, follow him on Twitter at @alanscott_faia.