Cleanroom air-recirculation systems typically account for a significant portion of the HVAC energy use in cleanrooms. High electric power density is normally required for fans to deliver large volume of airflows that were designed, supplied, recirculated, and exhausted within a given time. With the increasing demand for specific contamination control, it is important to optimize design of clean spaces. Best practice in cleanroom air system design includes right-sizing the systems in cleanrooms and adopting minienvironments. Implementing and integrating minienvironments in cleanrooms can improve contamination control and save significant energy.