Smart Solutions

Rawal’s APR Control Modulates Humidity, Stops Mold Invasion in Mixed-Use Space

To combat the signs of mold and mildew growth, a Southeastern U.S. house of worship installed the APR Control manufactured by Rawal Devices, Inc. to eliminate the humidity causing the problem. Thanks to the new control, the organization avoided major health effects and was able to restore its facility to full use.

Mold in Mixed-Use Spaces

The most consistent problem that mixed-use facilities—such as houses of worship, community centers, correctional facilities, sports complexes, theatres, and public buildings—face is the varying load conditions caused by constant shifts in occupancy. When direct expansion (DX) air conditioning (AC) equipment is applied to these types of facilities, it is designed for peak load conditions, which includes full occupancy and the necessary ventilation. Constant shifts in occupancy result in temporarily oversized AC equipment, leading to temperature and humidity swings, mold growth, short cycling, hard starts, coil frosting, liquid slugging, and ultimately the possibility of equipment failure.

This particular organization was a prime example of how a mixed-use facility can be affected by varying load conditions and oversized DX AC equipment. The large facility houses a preschool program, kids’ play room, nursery, childcare services, workout facility, and conference room in addition to the area where the congregation gathers for worship.

The facility is serviced by multiple DX AC systems that were unable to adapt to the constant shifts in occupancy. Several rooms, including the workout facility, kids’ play room, and conference room, were becoming extremely uncomfortable, and the maintenance staff started seeing signs of mold and mildew growth on the walls and ceilings.

High Humidity Identified as Cause

The mold growth and threat of viruses spreading throughout the facility caused the staff to shut down the rooms to protect the health of facility users. It was determined that high humidity was causing the mold growth. According to the Environmental Protection Agency (EPA), humidity levels should be kept within 30–60 percent indoors (ideally 30–50 percent) to decrease or prevent mold propagation. The facility was experiencing relative humidity levels between 70 and 80 percent—well above the EPA’s recommended levels.

It was determined that the constant shifts in occupancy in the spaces caused the DX AC system to short cycle. These inadequate run times lead to high humidity levels, ultimately resulting in mold growth. ASHRAE studies show that it takes an AC system approximately 15 minutes of run time with the evaporator coil temperature below dew point to begin useful moisture removal.

APR Control Stabilizes Humidity

Before the mold took root and became a considerable threat to members, the organization decided to install the APR Control, a continuous capacity modulation and dehumidification device manufactured by Rawal Devices since 1993. The APR Control allows a standard DX AC system to modulate its capacity to match changing load conditions to extend the system’s run time for better dehumidification capabilities.

The APR Control provided capacity control for the DX AC system. A humidistat was also installed to create an active dehumidification cycle. The APR Control helped lower and stabilize the humidity levels by matching the system capacity to the changing load conditions, thus preventing further mold growth. Additionally, the APR Control prevented other possible complications of DX systems.

The maintenance staff at the organization recognized that mold in itself poses a threat. Moreover, the costs of major repairs to the space, possible loss of rent, potential occupant relocation costs, and the possibility of litigation are significant concerns for any building owner. By installing the APR Control, the organization was able to avoid these issues, maintain a healthy environment, and return to normal daily operations.

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