Summertime HVAC in Healthcare Facilities

Heating, ventilation and air conditioning (HVAC) systems are typically designed to control odors, remove contaminated air and maintain indoor humidity and temperature at comfortable levels for occupants. HVAC systems in healthcare facilities are also intended to reduce the risk of transmission for airborne pathogens, especially for those occupants who are more vulnerable. In addition to patients and staff, some common vehicles into healthcare facilities for pathogens are water, building materials, equipment and air currents. Because of the additional concerns that health care systems must address, the American Institute of Architects (AIA) has developed guidelines for the design of HVAC systems for existing healthcare facilities, as well as the design and construction of new facilities.

Because environmental conditions such as temperature, humidity, surface moisture, wind vibration, sunlight and other conditions have an influence on microbes in the building environment, the summer months pose their own set of challenges to how well HVAC systems can successfully manage air quality. Relative humidity is defined as the ratio of the amount of moisture contained in the measured air to the maximum amount of moisture the air can contain at that specific temperature. The higher the temperature, the more moisture the air is capable of containing. The U.S. EPA recommends maintaining the relative humidity (RH) within buildings below 60%, with ideal conditions between 30 to 50% to prevent biological growth.  Although this may be more difficult to achieve during hotter, more humid summer months, there are steps you can take that will help successfully manage these types of conditions:

  • Monitor indoor humidity levels using simple, inexpensive meters
  • Routinely check your HVACS systems by a professional HVAC engineer/contractor for proper operation and evidence of mold
  • Cleaning practices should be performed in accordance with the National Air Duct Cleaners Association (NADCA) standards
  • Address moisture concerns and fix sources of moisture such as leaky roofs, pipes, water infiltration through slab, condensation on pipes and ducts, etc.
  • HVAC diffuser vent covers should not be soiled, they should be removed and cleaned periodically
  • Airflow speeds in excess of design criteria can lead to water droplets blowing from the coils and into the HVAC ductwork

Remember: any larger areas of fungal growth (more than one square foot) should be addressed by professional contractors who have trained personnel on staff, who will use appropriate engineering controls and work practices to help manage these issues.

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