What is the main purpose of the ASHRAE Standard 62.1?

• A. To set minimum filtration efficiency.
• B. To define acceptable indoor air quality comfort.
• C. To specify energy efficiency for HVAC systems.
• D. To provide guidelines for minimum outside air design based on maximum expected occupancy.

Answer: (D)

The main idea behind ASHRAE 62.1 is to ensure acceptable indoor air quality by prescribing the minimum outdoor air that must be supplied to spaces. It does this by tying ventilation requirements to how many people and what type of space are in use, so that enough fresh air is brought in to dilute indoor contaminants. In practice, the standard provides a Ventilation Rate Procedure (and a prescriptive path) that determines the outdoor air rate based on occupancy and space type, ensuring that even at maximum expected occupancy there is sufficient dilution for good IAQ.

That focus is why the guideline about minimum outside air design based on maximum expected occupancy is the best choice. The standard does include filtration considerations and other IAQ elements, but its core purpose is not filtration performance, not general comfort definitions, and not energy efficiency requirements—those are addressed in different standards or sections.