Best bang for buck to cut a Florida power bill?

The order matters more than the products

1. 1Air sealing. Unglamorous and cheap: seal the attic penetrations, top plates, can lights and duct boots before adding anything else.
2. 2Attic insulation, up to R-38 or better, once the sealing is done. Insulation over an unsealed ceiling is a filter, not a barrier.
3. 3Duct work. Seal it, and replace it if it is bad. Ducts in a 130-degree attic leaking a fifth of the air is common and expensive.
4. 4A radiant barrier, which helps here more than in most climates but far less than the first three.
5. 5Windows, last, for the reasons below.

Why windows are last

New windows are a genuine comfort and noise improvement and they can earn an insurance credit, but the energy payback period is long compared with everything above them. Buy them for the reasons in are impact windows worth it, and treat the energy saving as a bonus rather than the business case.

Measure rather than guess

A blower door test tells you how leaky the house actually is and where. It turns this list from general advice into a work order for your specific house, and it is inexpensive next to the work it directs.

The free half of it

• Change the filter on schedule. A blocked filter costs capacity and shortens equipment life.
• Keep the condenser clear of shrubs and clean the coil.
• Use ceiling fans in occupied rooms only — they cool people, not rooms.
• Shade the west-facing glass, which is where the afternoon load arrives.

If the system itself is due, get the sizing right before you buy: why four HVAC quotes give four different sizes.

What each step is worth, roughly

Air sealing and insulation change how hard the system has to work, which affects every hour of every day. Duct sealing recovers air you are already paying to cool. A radiant barrier reduces attic temperature, which helps the ducts and the ceiling.

Equipment replacement is the most expensive step and the one people start with. If the current system is not at the end of its life, do the first three and then re-size the replacement when the time comes: a tighter house often needs a smaller unit, which costs less to buy and less to run.