Quick answer
A high-efficiency AC upgrade replaces an older system with one rated around 16 to 22 SEER2, usually with a variable speed or two-stage compressor and a variable speed blower. In Miami, where systems run close to 3,000 hours a year, the higher efficiency cuts cooling costs noticeably and the longer, slower run cycles remove more humidity.
Written by Sylvia Denton, HVAC Guides Editor. Updated 2026-09-22.
SEER2 is the federal measure of how much cooling a system delivers for each unit of electricity over a season. The minimum for new central air in the Southeast is 14.3 SEER2. Many Miami homes still run systems that were rated 10 or 13 SEER under the old test, which is roughly 9.5 to 12.4 on the new scale.
The jump from an old 10 SEER unit to a 16 SEER2 system can cut the cooling portion of an electric bill by a third or more. Going higher, to 18 to 22 SEER2 with an inverter compressor, saves more, but each step costs more up front. The right level depends on how many hours your system runs, your FPL rate, and how long you plan to stay in the house.
Efficiency is only half the story in Miami. Variable speed equipment runs longer at low speed rather than blasting on and off, and those long, slow cycles pull far more moisture out of the air. For homes that feel cold but clammy, that humidity control is often the biggest comfort gain of the upgrade.
