Which kind of building strategy helps improve air flow through duct systems?

Minimizing the number of bends in a duct system is a fundamental strategy to improve airflow. Bends and turns in ductwork can create resistance to the movement of air, known as friction loss, and can disturb the smooth flow of air within the system. Each bend can reduce the system's efficiency by forcing the air to change direction, which can lead to turbulence and decreased pressure at the ducts’ outlets. By minimizing bends, you allow air to flow more freely, which enhances the overall effectiveness of the HVAC system, ensuring that conditioned air reaches its intended destinations more efficiently.

Larger duct sizes can help in reducing air velocity and lowering noise levels, but simply increasing size without regard for airflow dynamics may not address the issue of resistance caused by bends. Reducing air returns is counterproductive, as returns are critical for balancing airflow and maintaining pressure in the system. Installing extra supply ducts can potentially help distribute air better, but it does not address the inherent resistance created by bends in existing ductwork. Thus, focusing on minimizing bends directly contributes to a smoother, more effective airflow, making it the best strategy among the options presented.