Before ASHRAE (the American Society of Heating, Refrigerating and Air-Conditioning Engineers) Standard 62 was adopted, one of the most popular chilled water coil freeze protection solutions was simply closing off the outside air.
However, ASHRAE Standard 62 significantly increased required outside air ventilation rates. Now, flow-measuring outside air dampers are used to verify compliance with ASHRAE Standard 62. If the outside air dampers are closed during occupied operation, the building automation system (bas) alerts building operators that adequate outside ventilation air is not coming in and that indoor air quality will suffer.