Is that upgrade worth the cost?

An invented $150 installed price, less JEA's $50 smart thermostat rebate once you've confirmed you qualify, is a net cost of $100. ENERGY STAR says that, on average, a smart thermostat saves approximately 8% of heating and cooling bills, or $50 a year, and that savings depend on climate, comfort preferences and occupancy, with homes that are always occupied seeing less.

• At ENERGY STAR's $50 average: $100 ÷ $50.00 = 2.0 years.
• At an invented $25 a year, half the average, for a home that's rarely empty: 4.0 years.

Enter both as a low and high estimate to see the range. ENERGY STAR's figure is a national average, not a Florida estimate; the smart thermostat guide works through it for FPL and JEA bills.

An invented $2,400 heat pump water heater quote, less JEA's $350 rebate for a heat pump water heater, saving an invented 1,800 kWh a year. Use the figure from your own quote or the equipment's label instead. The only thing that changes below is the price per kWh, from JEA's rates effective October 1, 2026 with November fuel, before taxes and fees.

If your bills are usually above 1,000 kWh, the kWh the upgrade saves come off the higher price and the faster payback applies. If they're usually below, use the lower price. When they cross the line from month to month, a range is the honest answer.

When equipment has failed, you're buying something either way, so the question is whether the efficient model's extra cost pays back. Invented quotes: $6,200 for a basic system and $7,000 for one that qualifies for FPL's $200 instant credit (a new indoor and outdoor system rated SEER2 15.2 or higher, through an FPL Participating Independent Contractor). The efficient system is estimated to use an invented 1,200 kWh a year less.

• Extra cost only: $800 − $200 = $600, saving $171.10 a year at FPL's 14.26¢ above 1,000 kWh. Payback: 3.5 years.
• Whole price, the wrong comparison here: $6,800 ÷ $171.10 = 40 years.
• On JEA: JEA's $200 heating and cooling rebate (ENERGY STAR equipment, a pre-qualified contractor, applied for within 90 days) gives the same $600 extra cost; at 14.68¢ the payback is 3.4 years.

Enter the extra cost as the installed cost and the qualifying incentive in the incentives box. Ask for both quotes in writing, with the model numbers, so you can check the efficiency rating against the program's requirement.

The calculator subtracts confirmed upfront incentives from the installed cost. Not every incentive works that way. Programs we verified on October 31, 2026:

Program rules change. Check the current terms on the rebates page and with the utility before you count anything.

1. Start from kWh, not percentages: the equipment's yearly kWh now and after, from labels, spec sheets or a written estimate.
2. Value it at the price of your next kWh from the price per kWh calculator, not your all-in average.
3. Give a low and a high figure. If the low one still pays back in time, the decision is easy.
4. Don't add up percentage savings from upgrades that affect the same load. Each one works on what's left after the other.

• What are the model numbers and efficiency ratings, and do they meet the rebate program's requirement?
• Is the contractor an FPL Participating Independent Contractor or a JEA pre-qualified contractor, where the program needs one?
• Does the quote already show an instant discount, and who applies for any rebate paid later?
• How was the savings estimate worked out: from which kWh, at which price per kWh, and for how many months of use a year?
• What yearly upkeep comes with the new equipment, such as filters, service plans or subscriptions?

Answers in writing make every number in the calculator above something you can check later.

• The full price when you'd replace the equipment anyway. If the old unit has failed, the efficient model's payback is the extra cost over the model you'd otherwise buy, divided by the extra savings. Enter that difference as the installed cost.
• Savings in months the equipment doesn't run. A heating upgrade in Florida saves only in the months you heat.
• Upkeep left at zero. Subscriptions, filters or service plans reduce the yearly saving. Put them in the upkeep box.
• An incentive counted twice. An instant discount already on the quote shouldn't go in the incentives box as well.

Years to pay back, by net upfront cost (after confirmed incentives) and annual net savings. Read across from your net cost to your savings. A figure longer than the equipment is expected to last means it won't pay for itself on energy savings alone.