Why are cold air returns on the outside wall and heat vents on the inside walls?

Cold air returns are typically placed on outside walls to efficiently draw in the cooler air that accumulates near the Windows and walls, ensuring better circulation and preventing cold spots in the room. Heat vents, on the other hand, are located on inside walls to distribute warm air evenly throughout the space, as heated air rises and needs to circulate within the living area. This arrangement enhances overall comfort and energy efficiency by optimizing airflow and temperature regulation.