Ceiling change improves air pressure

New gasketed ceiling panels form a tight seal with the grid and reduce airflow leakage through the ceiling plane.

Photo courtesy of Armstrong Ceiling & Wall Solutions

Encompass Health Rehabilitation Hospital of Middletown, Del., is a provider of inpatient rehabilitation for people suffering from complex neurological and orthopedic conditions. Serving the state of Delaware, the hospital is accredited by The Joint Commission. The facility contains 40 beds and includes one patient room that functions as a negative-pressure infection isolation room. The room is 19 square feet and conditioned using one constant volume supply box and one dedicated exhaust fan.

The room was designed to operate at a minimum differential pressure of -0.020-inch water column (w.c.) in relation to the adjacent corridor. However, the exhaust fan for the space could not always achieve the required pressure, according to Kevin McNeil, director of plant operations for the hospital. As a result, sensor alarms in the corridor outside the room would go off anytime the door opened and pressure in the room dropped. 

“We tried a new fan motor to increase rpm and tried sealing the doors,” McNeil says, “but we were never able to consistently achieve the desired pressure. We thought about replacing the fan, but that had a big expense tied to it; plus, we would have had to rebalance and recertify everything. Our objective was to eliminate pressure variability and avoid fan replacement.”

Instead of replacing the exhaust fan to achieve the required room differential pressure and eliminate pressure variability, the hospital replaced the existing ceiling panels with Calla Health Zone AirAssure ceiling panels from Armstrong Ceiling & Wall Solutions, Colony, Texas.

Timothy Roaten, president of Eastern Air Balance of Manheim, Pa., a certified firm that tests airflow in buildings, recommended the switch.

“The single largest surface that needs to be sealed in health care facilities is the ceiling. This is vital today, as hospitals are being encouraged to create negative-pressure rooms to control the airflow and the potential spread of airborne particles,” says Roaten, an air testing specialist.

The new panels are designed with gasketed edges and form a tight seal when placed in a standard ceiling suspension system. This reduces airflow leakage through the ceiling plane up to more than four times that of panels without AirAssure performance, according to Roaten. In addition, in facilities where the air space above ceilings is shared with multiple rooms, the panels help reduce the risk of pathogen transfer between rooms.

The acoustic environment in the room improves as well because the panels are part of the Armstrong Total Acoustics portfolio, which offers a combination of sound absorption (0.80 noise-reduction coefficient) and sound blocking (ceiling attenuation class 40) in the same panel, providing noise control and speech privacy.

Thanks to the installation, the pressure differential in the room nearly doubled. According to Roaten, whose firm conducted tests before and after installation of the new panels, the target was to maintain the minimum -0.020-inch w.c. under all conditions. By changing the ceiling panels, room pressure increased to -0.0368-inch w.c., providing an 84% buffer above the design minimum. There were no measurable changes to the supply and exhaust airflow in the space. The only change was the replacement of the existing ceiling.

This increase eliminated the nuisance of room pressure alarms and the need to replace the exhaust fan. It also brought the room into compliance without costly upgrades to the HVAC system. In addition, the replacement of the ceiling only took one day, so extended downtime for the room was eliminated. Also eliminated were labor costs involved in caulking ceiling panel edges. 

“We knew the ceiling would make a difference but didn’t know how much,” Roaten says. “It performed much better than we imagined, nearly doubling the pressure differential in the room. We weren’t expecting that much of an increase.” 

McNeil agrees. “It was a significant improvement,” he says. “We are now able to maintain the required pressure throughout the day, which is especially important today because of the pandemic. If we needed another room that required negative pressure, I would highly recommend this system.”