Plan smarter upgrades with clear dual-fuel comparisons here. Adjust load, share, and seasonal performance quickly. Download results, share scenarios, and decide with confidence now.
Enter your assumptions. On large screens, inputs flow in three columns.
Sample scenarios for quick benchmarking. Replace with your own values for accurate results.
| Scenario | Heating demand (MMBtu) | HP share (%) | Elec ($/kWh) | Gas ($/therm) | Estimated savings ($/yr) |
|---|---|---|---|---|---|
| Mild winter home | 35 | 80 | 0.16 | 1.50 | 350 |
| Mixed climate home | 60 | 70 | 0.18 | 1.60 | 220 |
| Colder climate home | 90 | 50 | 0.20 | 1.70 | 80 |
Dual‑fuel savings are driven by delivered heating demand, relative fuel prices, and seasonal efficiency. For every 1 MMBtu of heat, a 90% AFUE furnace uses about 11.11 therms, while a heat pump at COP 2.8 uses roughly 105 kWh. At $0.18/kWh and $1.60/therm, that equals about $18.90 versus $17.78 per MMBtu, before fixed charges, annual service fees, and maintenance.
Heat pump share is the portion of annual heating met electrically. A 70% share typically covers shoulder seasons and mild winter hours, with gas handling cold snaps or defrost-heavy periods. In many mixed climates, 50–80% is realistic when the changeover temperature is set around 25–40°F (−4 to 4°C). If ducts leak or insulation is weak, a lower share can better represent longer backup runtimes.
The calculator escalates electricity and gas prices separately, then discounts future savings to today’s dollars. NPV is calculated as −incremental_cost + Σ(savings_t ÷ (1 + discount)^t). With $220 year‑1 savings, 2% average escalation, and a 6% discount rate, the present value of year‑10 savings is about 0.56× the nominal value. Use this view to compare upgrades against alternative investments.
Emissions depend on your grid factor (kg CO₂ per kWh) and the gas factor (kg per therm). A common planning value for gas is near 5.3 kg CO₂/therm, but local reporting can differ. When the grid is clean enough that electric heat at your COP emits less than gas heat, increasing heat pump share cuts CO₂. A carbon price converts the CO₂ delta into dollars, aligning bill and climate tradeoffs.
For robust decisions, run three scenarios: conservative, expected, and optimistic. Vary heat pump share by ±15 points, COP or HSPF by ±10%, and both utility rates across your last 12‑month range. If NPV remains positive and payback stays acceptable across scenarios, the upgrade is resilient. If results hover near zero, focus on controls, sealing, and proper sizing to stabilize performance.
It combines an electric heat pump with a gas furnace backup. Controls choose the most suitable source by temperature or efficiency, balancing comfort, cost, and reliability.
Start with 60–75% for a mixed climate. Reduce it for long cold snaps, weak insulation, or leaky ducts. Increase it for mild winters, strong COP/HSPF, and a higher changeover temperature.
Yes. Enter baseline cooling kWh and an expected improvement percentage. If cooling is not relevant, set cooling kWh to zero and the results will reflect heating-only impacts.
COP is efficiency at a condition or seasonal average. HSPF is a seasonal rating in Btu per watt‑hour. The tool estimates seasonal COP using COP ≈ HSPF ÷ 3.412.
Payback can be N/A if the incremental cost is zero/negative or annual savings are not positive. IRR can be N/A when cashflows never cross zero, such as persistent negative savings.
Run a calculation, then use Download CSV for a data file or Download PDF for a shareable report.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.