Home energy audit in Florida: how to do it yourself and when to call someone

A home energy audit is an orderly walk through your house to find where the electricity goes: air leaks, an uninsulated attic, broken ducts, an AC working overtime, a water heater set to 140 °F or something running 24 hours. You can do the DIY version in an afternoon with your 12 bills; FPL, Duke and TECO offer theirs for free; and a professional one with equipment costs $250 to $600 according to the DOE.

Where do I start: the bill, not the house?

Before opening a closet, open the 12 statements and write down each month’s kWh (/en/learn/how-to-read-your-fpl-bill or your utility’s guide). Two numbers orient you:

• Lowest month (January or February): your base usage without air conditioning.
• Highest month (July or August) minus the lowest: your “AC bill”.

If the gap is more than double, the audit focuses on cooling. If they are similar, the problem is the base: hot water, pool or something that never turns off. ENERGY STAR’s Home Energy Yardstick gives you, from a ZIP code, square footage and occupants, a 0-to-10 score against similar homes and how much of your usage is heating and cooling. It is free and takes five minutes.

What do I check in a DIY audit?

The Department of Energy publishes a guide for doing it without instruments. Adapted to Florida:

The DOE’s depressurization test, for hard-to-find leaks: close doors, windows and the fireplace flue, turn on every exhaust fan (bathrooms and kitchen) and pass a candle or incense stick along the suspect edges. Smoke that moves marks the leak.

What free audits does my utility offer?

All are free and all end in a list of recommendations and utility programs. They are worth doing.

Heads up: the utility’s audit is paid for by the company that sells you the kWh. It will tell you how to buy fewer; it will not tell you whether generating your own pays, it will not compare contracts, and it will not mention there is a minimum charge that solar does not remove. It is not bad faith, it is their role. That is why the independent diagnosis exists: someone with access to the whole market and no sales quota for a single product.

When should I call a professional with equipment?

The DOE describes the professional audit as an instrument-based review: a blower door (a fan in the doorway that depressurizes the house and measures how much air escapes), an infrared camera (shows leaks and insulation gaps as temperature patches), sometimes a duct leakage tester and gas and carbon monoxide detectors. It costs $250 to $600, and many contractors discount it if you then do the upgrades with them.

It is worth paying for when:

• You are about to replace the AC: the right size depends on how much air the house loses, and an oversized unit cools poorly and uses more (/en/learn/old-ac-and-your-bill).
• You are about to go solar: the system is sized on your usage; if you cut usage first, you buy fewer panels.
• The highest month doubles the lowest and you have already checked thermostat, filter and pool without finding the cause.
• Some rooms never cool or humidity persists: that is usually ducts or attic, not the equipment.

When NOT to do an audit

• If you use under 500 kWh a month: you are already efficient and the payback on any upgrade is slow.
• If you just moved in and lack a full summer of bills: do the DIY one first and wait for data.
• If you already know the cause (pool pump 12 hours, water heater at 140 °F): fix it and measure a month before paying anyone.

What to check before deciding

• Your 12 months of kWh and the gap between the highest and lowest.
• The hourly view of one summer week: when it spikes and how much stays on overnight.
• Water heater temperature, pool pump hours and thermostat setting: the three free fixes.
• AC age and SEER (/en/learn/what-is-seer).
• What your utility’s free audit offered and what it left out. With that, the diagnosis starts with your home’s real numbers.