Actually, yes. The most high-efficiency central AC systems on the market use variable flow for exactly this reason. Below that are two-stage systems (low and hi

Actually, yes. The most high-efficiency central AC systems on the market use variable flow for exactly this reason. Below that are two-stage systems (low and high flow), then single-stage systems. Reliability and cost does play a part in all of this, though. [0] AFAIK, the most efficient residential systems are ductless split systems, where you basically have a centralized compressor and distributed air handlers in individual rooms. This allows for variable flow and localized control, which reduces need. [0] https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_ratio#US_government_SEER_standards https://en.wikipedia.org/wiki/Seasonal_energy_efficiency_rat... > But when either replacing equipment, or specifying new installations, a variety of SEERs are available. For most applications, the minimum or near-minimum SEER units are most cost effective, but the longer the cooling seasons, the higher the electricity costs, and the longer the purchasers will own the systems, the more that incrementally higher SEER units are justified.