Wattsmart or ThermWise: which rebate pays more.

First, the gate before the math

Before either program pays anything, it has to apply to your house at all.

• Wattsmart Home (Rocky Mountain Power) needs an electric account on rate schedule 1, 2, or 3, with either electric heat or a central cooling system serving most of the home.
• ThermWise (Enbridge Gas) needs an Enbridge Gas account with gas as the primary heat source.

A lot of homes in Highland, Alpine, Lehi, American Fork, Cedar Hills, and Pleasant Grove have gas heat and Rocky Mountain Power electric service, which means the honest first answer for many people is to check both, because you might only clear one gate.

Then, the two pay differently

• Wattsmart Home pays per window. $50 each in an electrically heated home, $30 each in a centrally cooled or dual fuel heat pump home. The count of windows moves this number.
• ThermWise pays per square foot of glass. $2.50 per square foot, on a gas account. The size of the glass moves this number.

That difference means the same project can be worth more under one program than the other, depending on whether the house has a lot of small windows or a few large ones.

A worked example, for illustration only

Take a home replacing 10 windows, roughly 15 square feet of glass each.

• On an electrically heated account: 10 windows at $50 each comes to $500 from Wattsmart Home.
• On a gas heated account: 150 square feet at $2.50 comes to $375 from ThermWise.

Change the shape of the project and the answer flips. Swap two of those windows for large picture units and the square footage climbs while the window count stays the same, which moves the ThermWise figure up and leaves the Wattsmart figure exactly where it was.

These are illustrations built from the published per-unit rates. The only way to know a real number is to measure the actual openings against the account that actually qualifies.

The one requirement both programs share

Both programs require an ENERGY STAR window with a U-Factor of 0.22 or lower on the NFRC sticker. That rating decides whether a window qualifies for either program at all. Above 0.22, neither program pays anything.

What is gone, and what to keep

The federal window tax credit expired December 31, 2025. It does not apply to windows installed in 2026, under either program, regardless of what a quote might say.

Keep every NFRC sticker from every window that goes in, and keep the itemized invoice. Both applications are built around those two documents, and a missing sticker is the most common reason a rebate request stalls.