Smart Thermostat Payback
Calculator
Results
- Break-even (years)
- 2.246645 yr
- Net position at the horizon
- $880.53
- Total savings
- $1,100.53
- First-year saving
- $96.00
- Energy saved per year (kWh)
- 960 kwh
Cumulative cash flow crossing zero at break-even
- Cumulative cash flow
- Cumulative cost of doing nothing
- Cumulative cost with the upgrade
Year-by-year cash flow until break-even
| 1 | 96.00 | 96.00 | -124.00 | 1,200.00 | 1,324.00 |
| 2 | 98.88 | 194.88 | -25.12 | 2,436.00 | 2,461.12 |
| 3 | 101.85 | 296.73 | 76.73 | 3,709.08 | 3,632.35 |
| 4 | 104.90 | 401.63 | 181.63 | 5,020.35 | 4,838.72 |
| 5 | 108.05 | 509.68 | 289.68 | 6,370.96 | 6,081.29 |
| 6 | 111.29 | 620.97 | 400.97 | 7,762.09 | 7,361.12 |
| 7 | 114.63 | 735.60 | 515.60 | 9,194.95 | 8,679.36 |
| 8 | 118.07 | 853.66 | 633.66 | 10,670.80 | 10,037.14 |
| 9 | 121.61 | 975.27 | 755.27 | 12,190.93 | 11,435.65 |
| 10 | 125.26 | 1,100.53 | 880.53 | 13,756.66 | 12,876.12 |
Comparison
| Scenario | Total cost over the horizon | Cumulative energy cost | Net position at the horizon |
|---|---|---|---|
| Do nothing | 13,756.66 | 13,756.66 | 0.00 |
| With the upgrade | 12,876.12 | 12,876.12 | 880.53 |
Formula
saving(n) = Q × s × price × (1+g)^(n−1) − running cost= 2.25
Note
This is a simplified cash-flow model. It projects the prices, escalation rate and equipment costs you entered with a single geometric escalation and no discounting, no inflation adjustment, no financing costs and no tax treatment; savings are assumed to accrue evenly within each year, which is what the fractional break-even interpolates. Real energy prices, tariff structures, grants, weather, occupancy and equipment performance vary widely and change over time. A break-even of zero means the cumulative cash flow never crosses into positive territory within the horizon you chose. Get a professional energy assessment and a written quotation before committing to any of these measures.
More in Energy payback
See all →Frequently asked questions
Where does the savings percentage in the calculation come from?+
It's typically based on field studies showing smart thermostats save roughly 8-15% on heating and cooling costs through better scheduling, setback during unoccupied hours, and learning algorithms that reduce unnecessary runtime. That percentage is applied to your entered annual heating/cooling spend, so an accurate baseline energy cost is essential to a meaningful result.
Why would a smart thermostat save less for me than the average?+
If you already manually adjust a programmable thermostat consistently, or you're often home and rarely change the setpoint, a smart thermostat mainly automates habits you already have, which caps the realistic savings well below the average. The biggest savings go to households with irregular schedules or those who previously left a single setpoint running all day and night.
Does the payback include installation cost?+
It should include both the device cost and any professional installation fee, since many models need a C-wire or compatibility check with heat pumps, and DIY installation isn't always possible. If you're installing it yourself and are compatible with your existing wiring, your actual payback will be faster than an estimate that assumes professional installation.
Are utility rebates factored into the payback period?+
A properly built calculator subtracts any smart thermostat rebate from many utilities (commonly $25-100) from the upfront cost before computing payback, which can cut the payback time substantially on an inexpensive device. Check with your local utility since these programs change frequently and aren't always applied automatically.
Why is the payback often under a year for such a low-cost device?+
Smart thermostats are one of the cheapest energy-efficiency upgrades available, typically $100-250 installed, while still capturing a meaningful percentage of a household's largest utility expense. That combination of low cost and a real percentage cut on a large bill is why paybacks under 12 months are common and not a sign of an unrealistic assumption.