What should be ensured regarding return air spaces in relation to hallways?

In ventilation design, it is acceptable to have return air spaces located in hallways that have three or more doors. This is due to the fact that hallways often serve as a transition area for air movement between different rooms, and having return air ducts in these spaces can help ensure efficient circulation of conditioned air. When there are multiple doors in a hallway, it allows for a more effective blending and return of air from adjacent rooms, which can assist in maintaining balanced air pressure throughout the spaces served by the HVAC system.

When considering ventilation efficiency and air quality, it's important to recognize that the presence of multiple doors encourages air exchange. Thus, having return air spaces in these specific configurations is beneficial for the overall airflow dynamics in a building.