Depending on the building and its geographic location, there are several techniques for specifying HVAC systems in nonresidential buildings. A new or existing building each has its own requirements and mechanical engineers must understand the client’s needs, the codes and standards, humidification/dehumidification needs, energy efficiency goals and the specific building requirements to successfully design a system. Based on recent issues brought on by the COVID-19 pandemic, indoor air quality has become more of a focus for mechanical engineers specifying or retrofitting HVAC systems