Building Green always does a great job at breaking down current research and analysis so that it is accessible and most of all actionable. This article is a good read for building owners and designers that are struggling to determine the most appropriate response to the pandemic.
In contrast to droplets, aerosols act like smoke. After being expelled, they linger in the air for minutes to hours, get diluted by air currents, and can be taken up and dispersed by HVAC systems. Image: HKS
The benefits to simply bringing buildings up to speed with best practices for IAQ (Indoor Air Quality), including adequate ventilation, filtration, and pathway interruption for pollutants are indisputable, and there is lots of room for improvement in our current building stock. For most buildings, a focused effort to get those basics right could not only reduce transmission pathways, but could generally improve occupant health and performance.
For buildings serving sensitive populations, and design teams contemplating measures that are above and beyond those best practices, the Aerosols and Micro-droplets: HVAC Approaches During COVID-19 article includes two new tools to help you evaluate the efficacy of those measures, and validate the best path forward. Available tools include FaTIMA from NIST and the previously mentioned Flu Infection Risk Estimator Tool from BranchPattern.
Big picture, now is the time to get the basics right, first and foremost. Not everyone can or should turn their building into a hospital, but with a layered approach, we can reduce the probability of transmitting infection, and support the health of our building occupants.
James Reason, PhD, coined the “Swiss Cheese Model,” which shows how imperfect safeguards can be layered to reduce risks. In the COVID-19 context, enhanced HVAC strategies will never fully protect occupants from the virus, but they could be another layer in addition to the behavior change measures represented here.
Image: Cleveland Clinic
