What SEER means on your air conditioner and why it matters in Florida (2026)

SEER (Seasonal Energy Efficiency Ratio) measures how much cooling your air conditioner delivers for each unit of electricity it uses over a cooling season. A higher number means fewer kWh for the same cooling. It matters more in Florida than anywhere else because, according to FPL, air conditioning accounts for roughly 50% or more of the annual electric bill in most Florida homes.

What exactly does SEER measure?

It is the ratio between cooling delivered (in BTU, the unit of heat the system removes from the house) and electricity consumed (in watt-hours) across a typical cooling season. If two units deliver the same cooling and one is SEER 10 while the other is SEER 20, the second uses roughly half the electricity to do the same job. See BTU and SEER in the glossary.

Think of SEER as a car’s miles per gallon: it does not tell you what you will spend (that depends on how much you drive), but it does tell you how far each dollar of fuel goes.

What changed with SEER2 in 2023?

On January 1, 2023 the Department of Energy (DOE) switched to a test method closer to a real installation, with more airflow resistance from ducts. The result is called SEER2, and its numbers come out slightly lower than old SEER for the same unit. For the Southeast region, which includes Florida, the legal minimum for split systems under 45,000 BTU is 14.3 SEER2, roughly 15 SEER on the old scale. In this region the rule is enforced by installation date: a unit that does not comply cannot be installed even if it was manufactured earlier.

The equivalence details and regional rules are on the DOE and SEER2 pages listed in the sources.

How much more does a 10-year-old unit cost to run?

Per the DOE, even if your air conditioner is only 10 years old, replacing it with a newer, more efficient model can save 20% to 40% of your cooling energy costs. The same DOE notes that today’s best units use 30% to 50% less energy than those built in the mid-1970s.

Translated to a Florida bill: if cooling is half your bill (FPL) and the new unit cuts that cooling by 20-40% (DOE), the effect on the total bill is on the order of 10% to 20%. That is a range, not a promise: the real number depends on run hours, your thermostat, and the condition of your ducts and insulation.

Heads up: SEER is measured in a lab with perfect ducts. If 20-30% of the air is lost through leaky ducts, as the DOE estimates for a typical house, an 18 SEER2 behaves like something much lower. That is why buying the most expensive unit without checking the house is the most common way to pay for efficiency that never shows up.

When replacing for SEER does NOT make sense

• When the unit is under 8-10 years old and works well: the typical lifespan the DOE cites is 12 to 15 years, and the savings will not cover the cost quickly.
• When the real problem is leaky ducts or an uninsulated attic: the money goes further there.
• When the unit is the wrong size: a new unit of the wrong size repeats the problem with a new label. Check right-sizing first.
• When the bill is already low: a high SEER pays back through run hours; with little use, payback is slow.

How does SEER relate to solar?

Solar produces kWh; SEER decides how many kWh you need. An old unit forces you to install more panels for the same comfort, and those panels cost money every month. In our diagnosis we review the A/C before calculating how many panels you need: sometimes the right answer is fewer panels and an efficient unit. You are right to distrust anyone selling panels without asking what year your A/C is.

What to check before you decide

• The label on the current unit: year of manufacture and SEER (or SEER2). If it is missing, assume it is below the minimum.
• How many hours a day it runs in summer: a thermometer and your bill history will tell you.
• A duct leakage test and a photo of the attic insulation before buying anything.
• That the new quote lists SEER2 (not SEER) and a Manual J load calculation, not a square-footage rule of thumb.
• Your kWh usage for the last 12 months, to know what share goes to cooling. If you are not sure how to read it, start with what a kWh is.