Purdue Physical Facilities has worked with the Protect Purdue Building and Infrastructure and Medical Advisory Teams on the specific adjustments made to building HVAC systems. These entities considered and are continuously monitoring Centers for Disease Control and Prevention (CDC) and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommendations.  It is important to note that the HVAC strategies described below are only one part of the comprehensive Protect Purdue Plan. Additional actions, such as de-densifying spaces and wearing masks correctly to minimize viral load, are also critical components.
HVAC performance has been optimized in as many buildings as possible with an emphasis on high occupancy areas. HVAC modifications include the following:
Re-programming air handling units to maximize outdoor air percentage and air changes per hour when classes are in session in large classrooms and high occupancy areas. This essentially means that more outdoor air will cycle through the spaces more frequently. Additionally, due to the de-densification of instructional spaces by 50%, the effective amount of outdoor air per person will be higher. Re-programming air handling units to run 24/7 to increase air filtration where feasible.  Changing current air filters for higher performance filters where feasible.
All of these HVAC optimization efforts have been implemented in concert with the capabilities of the existing systems and infrastructure to ensure that appropriate temperature and relative humidity conditions are maintained.