Home Retrofit Bundle Payback
Calculator
Results
- Break-even (years)
- 12.904612 yr
- Net position at the horizon
- $50,092.75
- Total savings
- $73,092.75
- First-year saving
- $1,444.00
- Energy saved per year (kWh)
- 12,100 kwh
- Simple payback (years)
- 13.577331 yr
- Escalated saving multiple (years)
- 47.575415 yr
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 | 1,444.00 | 1,444.00 | -21,556.00 | 3,080.00 | 24,636.00 |
| 2 | 1,494.82 | 2,938.82 | -20,061.18 | 6,252.40 | 26,313.58 |
| 3 | 1,547.16 | 4,485.98 | -18,514.02 | 9,519.97 | 28,033.99 |
| 4 | 1,601.08 | 6,087.06 | -16,912.94 | 12,885.57 | 29,798.51 |
| 5 | 1,656.61 | 7,743.68 | -15,256.32 | 16,352.14 | 31,608.46 |
| 6 | 1,713.81 | 9,457.49 | -13,542.51 | 19,922.70 | 33,465.22 |
| 7 | 1,772.72 | 11,230.21 | -11,769.79 | 23,600.38 | 35,370.17 |
| 8 | 1,833.41 | 13,063.62 | -9,936.38 | 27,388.40 | 37,324.78 |
| 9 | 1,895.91 | 14,959.53 | -8,040.47 | 31,290.05 | 39,330.52 |
| 10 | 1,960.29 | 16,919.81 | -6,080.19 | 35,308.75 | 41,388.94 |
| 11 | 2,026.59 | 18,946.41 | -4,053.59 | 39,448.01 | 43,501.60 |
| 12 | 2,094.89 | 21,041.30 | -1,958.70 | 43,711.45 | 45,670.15 |
| 13 | 2,165.24 | 23,206.54 | 206.54 | 48,102.79 | 47,896.26 |
| 14 | 2,237.70 | 25,444.23 | 2,444.23 | 52,625.88 | 50,181.65 |
| 15 | 2,312.33 | 27,756.56 | 4,756.56 | 57,284.65 | 52,528.09 |
| 16 | 2,389.20 | 30,145.76 | 7,145.76 | 62,083.19 | 54,937.44 |
| 17 | 2,468.37 | 32,614.13 | 9,614.13 | 67,025.69 | 57,411.56 |
| 18 | 2,549.92 | 35,164.05 | 12,164.05 | 72,116.46 | 59,952.41 |
| 19 | 2,633.92 | 37,797.98 | 14,797.98 | 77,359.95 | 62,561.98 |
| 20 | 2,720.44 | 40,518.41 | 17,518.41 | 82,760.75 | 65,242.34 |
| 21 | 2,809.55 | 43,327.97 | 20,327.97 | 88,323.58 | 67,995.61 |
| 22 | 2,901.34 | 46,229.31 | 23,229.31 | 94,053.28 | 70,823.98 |
| 23 | 2,995.88 | 49,225.18 | 26,225.18 | 99,954.88 | 73,729.70 |
| 24 | 3,093.26 | 52,318.44 | 29,318.44 | 106,033.53 | 76,715.09 |
| 25 | 3,193.55 | 55,511.99 | 32,511.99 | 112,294.53 | 79,782.54 |
| 26 | 3,296.86 | 58,808.85 | 35,808.85 | 118,743.37 | 82,934.52 |
| 27 | 3,403.27 | 62,212.12 | 39,212.12 | 125,385.67 | 86,173.55 |
| 28 | 3,512.86 | 65,724.98 | 42,724.98 | 132,227.24 | 89,502.26 |
| 29 | 3,625.75 | 69,350.73 | 46,350.73 | 139,274.06 | 92,923.33 |
| 30 | 3,742.02 | 73,092.75 | 50,092.75 | 146,532.28 | 96,439.53 |
Comparison
| Scenario | Total cost over the horizon | Cumulative energy cost | Net position at the horizon |
|---|---|---|---|
| Do nothing | 146,532.28 | 146,532.28 | 0.00 |
| With the upgrade | 96,439.53 | 96,439.53 | 50,092.75 |
Formula
cumulative(n) = −(cost − grant) + Σ (Q × r × price × (1+g)^(k−1) − maintenance)= 12.90
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
Why does bundling multiple upgrades change the payback math compared to doing each separately?+
Bundled measures interact — insulation reduces the heating/cooling load, which in turn reduces the savings available from a smart thermostat or a new HVAC system, since there's less energy being used in total for it to trim. A good bundle calculator applies measures in sequence (envelope first, then equipment, then controls) and reduces each subsequent measure's savings potential to avoid double-counting.
Is it true that bundling always gives a shorter combined payback than doing measures one at a time?+
Not necessarily — bundling can shorten payback by capturing labor and mobilization efficiencies (one contractor visit, shared scaffolding or access costs) and rebate programs that require multiple measures. But it can also lengthen the blended payback if you bundle a fast-payback measure like LED lighting with a slow one like windows, since the combined dollar-weighted payback sits somewhere between the two.
How should I interpret a single payback number for a bundle with very different individual paybacks?+
Look at the underlying breakdown, not just the blended figure — a bundle showing an 8-year combined payback might contain a thermostat paying back in 8 months and window replacement paying back in 20 years, and the fast component is masking the slow one. If budget is limited, it's often smarter to implement the fast-payback measures now and defer the slow ones rather than committing to the full bundle at once.
Does the calculator account for rebates or financing that only apply to whole-home bundles?+
Many utility and government programs (like whole-home retrofit grants) require a minimum combination of measures or a pre/post energy audit to qualify, and those rebates can be large enough to flip a marginal bundle into an attractive one. A properly built calculator should let you enter bundle-specific incentives separately from per-measure rebates, since claiming both isn't always allowed.
Why is the total energy savings usually less than the sum of each measure's individual savings?+
This is the interaction effect: each measure reduces the base load that later measures act on, so insulation done first means the furnace replacement afterward saves less in absolute terms than it would have on an uninsulated house. Adding up each measure's stand-alone savings independently typically overstates total bundle savings by 10-30% depending on how the measures overlap.