What standard is applicable for a 2-story multifamily building?

The correct answer is based on the specific requirements for ventilation in residential buildings. ASHRAE 62.2 is the standard that governs ventilation and indoor air quality specifically for residential spaces, which includes multifamily dwellings. It addresses the need for appropriate ventilation rates in homes to ensure a healthy indoor environment by recognizing the unique characteristics of residential properties, including multifamily buildings.

ASHRAE 62.1, on the other hand, is designed for commercial buildings and is not applicable to residential settings. ASHRAE 90.1 pertains to energy efficiency standards for buildings, primarily focused on commercial buildings rather than residential. ASHRAE 189.1 is a standard for the design of high-performance green buildings, which encompasses broader sustainability aspects, but it does not focus specifically on the ventilation needs of residential spaces.

Therefore, ASHRAE 62.2 is the most relevant and applicable standard for establishing appropriate ventilation practices in a 2-story multifamily building, ensuring that air quality is addressed effectively as per residential needs.