What is Air Exchange

Air exchange is the measure of how many times the air in a room is replaced by conditioned air in an hour.  Why do we care? The conditioning of air does more than just change the temperature of the air. It changes the moisture level, removes dust particles, and adds fresh air to a room. Fresh air in a room dilutes any contaminates in the room.  With winter approaching and the prospect of your employees and customers bringing colds and virus’ in your facility, one of your tools to combat those virus’ is to introduce fresh air and flush the contaminates outdoors through your existing HVAC system. 

  • The average home air exchange rate is normally designed at 2-4 air exchanges in an hour with 5-10 percent outside air which results in 90 percent recirculated air.  These numbers can be significantly lower based on length of time your system is running. 
  • Most public spaces (i.e. business facilities) should have a minimum of 6 air exchanges in an hour with 10-25 percent outside air which results in 75 percent recirculated air. 
  • Comparatively, hospitals can be as many as 20 air exchanges in an hour with 100 percent outside air which results in 0 percent recirculated air.

The exact optimum air exchange rate is dependent on the size of the room and the number of people in the room, recent studies have indicated that an exchange rate of nine times per hour was effective in reducing the spread of virus’.  Signs of low airflow/exchange rate are:

  1.  The unit turns off during occupied times (there are no air exchanges when air is not moving through the system)
  2. Air feels stuffy

Your air exchange rate should be verified once every couple of years.  Call McCook Mechanical Services at (308) 737-9315 to get your air exchange rate checked today!!