COVID Proved the Importance of Airflow in Buildings

December 18, 2020
Cedric Steiner

Officials at the Children’s Hospital of Philadelphia have the ability to convert several floors into airborne infection isolation rooms (AII), or more commonly termed negative pressure rooms, with the flip of a switch.

The airflow in your facility may have been overlooked prior to coronavirus disease 2019 (COVID-19) but that has changed. When it comes to infection control and prevention it’s time to focus on this critical element for patient and provider safety. Take a moment to consider where the air supply directly overhead comes from. Infectious agents or suboptimal environmental conditions, perpetuated by the air supply, will exacerbate infections.

In order to manage a highly transmittable disease like COVID-19, organizations have used altered airflows or more specifically negative pressure within their facilities to increase air exchanges and optimize fresh outdoor air. I first became involved in such a project while serving at a skilled nursing facility. In order to manage the oncoming crisis and uncertainty associated with admissions, quarantine procedures, and hospital capacities, I worked with Shelly Miller and a group of colleagues at the University of Colorado to convert a rehabilitation hallway into a negative pressure space. We performed computational fluid dynamics and particle-based modeling to test containment. The isolation space was successful both in our model and in practice at controlling transmission between residents and staff. Due to the cancelation of elective surgeries and the subsequent pause in rehabilitation services, the negative pressure space provided an important revenue stream and community resource for the elderly requiring skilled COVID-19 nursing care.

When the Boston Globe recorded Steward Health Care’s preparations at Carney Hospital to become the nation’s first dedicated coronavirus care center, they stressed the transformation of a floor into negative pressure. Carney designated a team of doctors and an operating room within the coronavirus care center to prevent transmission to the broader hospital population. But it was the negative pressure and separate airflow that was arguably the largest factor making it a “hospital within a hospital”.

Outbreaks like the Ebola virus disease of 2014-2016 encouraged the thinking behind building designs to include the capability of achieving negative pressure over large areas. Engineers at Children’s Hospital of Philadelphia foresaw a looming pandemic and designed their buildingswith the ability to respond. Hospital officials have the ability to convert several floors into airborne infection isolation rooms (AII), or more commonly termed negative pressure rooms, with the flip of a switch. In the most recent pandemic this innovation and foresight has been shown to be tremendously beneficial.

According to Rachel McCarthy, vice president of plant operations at Children’s Hospital of Philadelphia, the hospital’s newest design has the ability to convert 2 floors, 3 wards, and over 150 rooms to airborne infection isolation rooms. The building management system (BMS) uses computer software to adjust the mechanical and electrical equipment throughout the building to achieve the desired results. At the request of administration and the infection control prevention team this system can be turned on to achieve the desired airflows throughout the building. But this requires necessary infrastructure. Controls, equipment, and sensors need to be installed and building management needs to be trained. I’m convinced these improvements should be a future investment in public health that should not only be in hospitals but other healthcare settings like skilled nursing facilities. As Rachel McCarthy puts it, “managing a pandemic without a problem requires PPE, testing, and negative pressure.” A three-prong approach.

Smart Buildings

Nick Clements, PhD, is a lead consultant at WSP USA, a globally recognized professional services firm specializing in infrastructure and an expert in building technology systems. He envisions a smart building with integrated infection controls. In a recent conversation, he outlined some innovations and challenges currently being explored in new building design across transportation, manufacturing, and healthcare. “Smart building” or building automation is used to denote buildings with integrated controls and data collection. This often involves the automation of multiple interrelated systems like HVAC, electrical, lighting, access control, and security systems through a building management system (BMS). Imagine taking this a step further where patient data and healthcare provider information is integrated into the building.

Clements discussed a scenario where future infections would be identified rapidly before they could spread. This could be done through a BMS that contained integrated patient data and diagnostic technologies employed in monitoring airflows.

For example, microfluidic systems and biosensors, used in clinical diagnostic purposes, could be integrated into a building system to provide clinical data. One type, the local evanescent array coupled (LEAC) biosensor uses optical immunoassay sensors that permit the detection of up to hundreds of target biomolecules and viruses. The chemical and biological engineering program at Colorado State University has a group focused on this technology. These sensors requiring no reagents are low cost and operate as a lab-on-a-chip with integrated circuits.

These diagnostic tools could notify and confirm the spread of an infection. An integrated BMS that contains pressure monitors could also be used to adjust pressure zones and air supply, further protecting a region within a hospital. When combined with patient and healthcare tracking this information could be used to identify the source of an infection. According to Clements, “the challenges of a smart building require the whole organization to innovate.” In a truly integrated BMS, many monitors and systems need to feed back into the control platform. Currently, these systems are often standalone or siloed in a BMS and require a control engineer to integrate the data—a significant burden. A cloud-based system could alleviate difficulties in staffing IT technicians and data management scientists.


The current COVID pandemic will spur innovation most likely in the direction of vaccines, testing, and airflows. When it comes to airflows keep an eye on ANSI/ASHRAE/ASHE Standard 170-2017 which currently details guidelines for environmental controls within healthcare facilities. The standard, which establish the parameters for ventilation of healthcare facilities, will need to guide decisions between infection control teams and building management. Standard 170-2017 allows retrofits to be made to convert standard patient rooms into AIIR facilities. Infection control teams should be in discussion with facility management on these possibilities if we are to expect any future improvement in managing infectious agents similar to COVID-19. I expect the future holds some exciting building management tools for the infection control preventionist.

Cedric Steiner is a Licensed Nursing Home Administrator in Lancaster County, Pennsylvania. He can be contacted at involving the use of negative pressure for immediate or future COVID relief.