A smart thermostat can lower heating and cooling costs, but an app is not a guaranteed saving. ENERGY STAR’s published FAQ describes average savings of approximately 8% of heating and cooling bills, or about $50 a year, for its certified smart thermostats. Those are the program’s benchmarks, not a promise for each house.
Your result depends on what changes compared with your existing controls and habits. Someone already using an effective schedule has less room to save than someone conditioning an empty house at the same setting all day. This guide separates that evidence from our illustrative purchasing budgets.
Correction, October 23, 2026: the previous version presented invented household examples as real-world results and stated an unsupported $50–$180 range for most homes. Those claims have been replaced with an attributed benchmark and explicitly hypothetical calculations. No customer homes were monitored for this article.
What the evidence actually measures
ENERGY STAR’s product criteria use aggregated customer-home data to evaluate savings metrics. That is stronger evidence than assuming a feature saves money because it appears on a specification sheet. It still does not establish the saving for your climate, equipment and routine.
Also distinguish runtime from energy. A multistage or variable-speed system can draw different power at different times. Fewer hours on a thermostat chart do not necessarily translate into the same percentage reduction in kWh. For a gas furnace, heating fuel and blower electricity are separate costs.
The published 8% and $50 figures should not be treated as a formula tying every household’s bill to one fixed annual total. Use a relevant percentage only as a scenario, state which spending it applies to, and compare the result with a less favorable case.
Use heating and cooling spending as the base
Do not apply an HVAC saving percentage to your whole electric bill. Refrigeration, cooking, water heating and EV charging are not automatically reduced by a space-conditioning thermostat.
For a hypothetical home with $1,200 in annual heating and cooling costs, an assumed 8% reduction is $96 a year. If the entire household energy bill is $2,400, using 8% of the whole bill would show $192 and double the modeled saving without justification.
A combined gas and electric household needs a consistent baseline. Record both relevant fuels, separate unrelated uses where practical, and use the same observation period. One unusually mild month after installation is not enough to establish an annual control saving.
Three purchase budgets you can reproduce
These are hypothetical inputs, not current product quotes, case studies or observed results. Installation costs, rebates and actual savings must be checked for your project.
Budget A: a $200 net installed cost and $50 annual saving. Simple payback is $200 ÷ $50 = four years. Over five years, the modeled energy reduction totals $250, leaving $50 after the purchase. There is no discounting, financing or future repair in this calculation.
Budget B: a $300 net installed cost and $30 annual saving. Payback is ten years. That is a weaker financial case even if the phone control is useful. Assign convenience its own value instead of increasing the energy estimate to justify the purchase.
Budget C: a $250 installed quote with a separately verified $100 rebate. Net cost is $150. If the household’s $1,200 HVAC budget falls by an assumed 8%, the $96 annual saving implies 1.6 years of simple payback. At a 3% saving instead, the annual reduction is $36 and payback becomes 4.2 years.
These cases show how the same device can have a different purchasing case when installation, eligibility or the starting schedule changes. The ownership comparison calculator can add recurring service fees or repair allowances, but its electricity inputs do not automatically model gas consumption.
Compare with the controls you already own
A manual thermostat can implement a schedule if someone consistently adjusts it. A programmable unit can automate fixed times. A smart unit may add remote access, occupancy features and other controls, depending on the model and service.
The fair comparison is the additional benefit over your current behavior. If you already use an effective schedule, buying another controller does not recreate the full difference between a scheduled and unscheduled home. Check whether features require an ongoing subscription and whether essential functions work without it.
For irregular schedules, occupancy features may be useful. For a predictable routine, an existing programmable unit may be enough. Check comfort, accessibility and household preferences as well as the price; a schedule that people repeatedly cancel is unlikely to deliver its modeled result.
Heat pumps need a separate recovery check
A furnace-style deep setback is not a universal heat-pump instruction. DOE’s air-source heat-pump guidance recommends compatible thermostats that recover gradually to avoid unnecessary resistance heat.
Our heat-pump setback analysis demonstrates how reduced heat demand can still produce a higher electricity bill if recovery uses more resistance backup. Its numbers are hypothetical, but the distinction between heat delivered and electricity consumed is essential.
Confirm the controller supports the installed compressor stages, backup system and equipment requirements. Have a qualified installer check configuration when needed. Do not disable backup heat or apply another home’s lockout settings solely to pursue a lower bill.
Get an installed quote and verify offers
Use the manufacturer’s compatibility checker and installation guidance before ordering. A conventional low-voltage thermostat is not interchangeable with every communicating or line-voltage heating system. The presence or absence of one wire alone does not settle complete system compatibility.
Ask the quote to separate the controller, necessary accessories, wiring work and labor. If an existing controller already works, include the full replacement cost when calculating the benefit of an upgrade. Do not assume installation is free because the product is advertised as easy to install.
Verify rebates with the utility or program administrator. Check the exact model, purchase channel, application deadline and enrollment terms. A demand-response offer may involve event-based adjustments; understand opt-outs and any effect on compensation before including it in your budget.
Check results without claiming a laboratory test
Keep a record of installation cost, settings, occupancy and relevant fuel use. Compare similar-weather periods and note other changes, including equipment replacement, insulation or a different electricity tariff. Those changes can explain part of a bill reduction.
On a time-of-use plan, a lower bill may reflect movement to cheaper hours rather than reduced kWh. Our rate-plan comparison shows the distinction. A thermostat can affect both consumption and timing, but those effects should not be counted twice.
For wider energy savings, see how to lower an electric bill. A controller cannot compensate for every building or equipment problem, and its payback should be assessed alongside the home’s actual needs.
FAQ
How much should I expect to save?
Use the ENERGY STAR benchmark as context, then build a scenario from your own HVAC spending and current behavior. An average does not guarantee a minimum saving. Test a smaller improvement before deciding whether the purchase pays back.
Is smart always better than programmable?
No. The right choice depends on compatibility, the household’s schedule and which functions it will use. Compare the extra installed cost with the additional benefit over the controller already available.
Should I apply a 7–10-degree setback to my heat pump?
Do not apply a generic furnace schedule without checking the heat pump’s guidance and recovery controls. Equipment, backup heat and comfort requirements affect the result.
Are the purchase costs in this guide current retail prices?
No. The three budgets are hypothetical arithmetic examples. Get an installed quote and verify any rebate yourself. The cited agency guidance was checked October 22, 2026.