Heat Pump Upgrade Calculator

This calculator weighs keeping your heat pump against replacing it with a new one. Describe the old heat pump by its ENERGY STAR listing, the year it was made, or the ratings on its nameplate; pick the new one from the ENERGY STAR list or enter its ratings; and give your system size and state, or your old heat pump's yearly electricity from your bills. It works out your heating and cooling need, each heat pump's yearly electricity and cost, the yearly saving, the net cost of the new heat pump, the simple and discounted payback, and the cost over the years you choose of keeping the old unit, replacing it now, or replacing it when it wears out.

Equipment and climate figures come from federal sources only: ENERGY STAR (EPA), DOE efficiency standards and test procedures, NOAA climate normals and EIA electricity prices. Older and newer ratings are never mixed. You set the installed price; the opening example and each worked example carry a round illustrative price, labelled as such.

Purpose and model boundary

This calculator compares keeping the heat pump you have with replacing it with a new one. It works out the heating and cooling your home needs, from your bills or from your state's climate and your system's size, the electricity each heat pump needs to deliver them, and the cost at your electricity price, and sets the yearly saving against what the new heat pump costs installed. Over the number of years you choose, it compares keeping the old heat pump, replacing it now and, when you say how many years the old one has left, replacing it when it wears out.

Every figure on this page is computed by the spreadsheet; the page adds nothing to it. It covers running cost and purchase cost only, for the same ducts or indoor units; a change of distribution system is not modelled.

Inputs and units

• The old heat pump, described in one of three ways: a model from the current ENERGY STAR list, if it is still listed; the year it was made, for which the calculator uses the federal minimum ratings for your state's region; or its SEER and HSPF from the nameplate or AHRI certificate (SEER 6 to 40, HSPF 4 to 20), with the basis of those ratings: SEER2 and HSPF2 (rated 2023 or later), SEER and HSPF (rated before 2023), or Unknown.
• Type: ducted split, ductless mini or multi-split, or single package, for each heat pump. For a listed model, choose the type first, then pick the model from that type's list, where each entry reads "Brand | Outdoor model".
• Your heating and cooling need: the size of your system, 0.5 to 6 tons, and where the need comes from: an estimate from your state and system size, or your old heat pump's yearly cooling and heating electricity from your bills. Optionally, your own heating and cooling degree days, which replace your state's figures.
• Backup heat: none beyond the rating, or electric resistance, with the share of the year's heat it supplies, from 0 to 1. The same share applies to the old and the new heat pump.
• The new heat pump: a model from the current ENERGY STAR list, or the SEER2 (10 to 40) and HSPF2 (5 to 20) from its AHRI certificate.
• Price: the state, which sets the default electricity price, and your own electricity price in dollars per kWh (0.01 to 2.00), optional.
• Purchase and finance: the installed price of the new heat pump, which is always yours to set; extra work such as permits, electrical or duct work; sales tax; verified incentives; removal; the old unit's sale value; yearly upkeep of each unit; the years the old unit has left; the new unit's expected life; the yearly change in electricity prices; the discount rate; and the years to compare.

Heating and cooling needs are in million Btu (MMBtu) a year of heat delivered or removed. Electricity is in kWh, fuel in US gallons or therms, efficiency ratings in Btu per watt-hour (CEER, SEER2, HSPF2) or as a fraction (AFUE), and money in dollars.

Governing relationships

• Estimated need: cooling need = system size (tons x 12,000 Btu/h) x 1,000 cooling hours x your state's cooling degree days / the US figure; heating need = system size x 2,080 heating hours x 0.77 x your state's heating degree days / the US figure. The 1,000 and 2,080 hours and the 0.77 adjustment are DOE's representative use cycles from the 2016 edition of its test-procedure rule, where the heating hours apply to a heat pump's Region IV design heating requirement. Two steps are this calculator's own, labelled approximations: that requirement is taken equal to your system's nominal size, and the national hours are scaled by your state's degree days.
• Need from your bills: your old heat pump's yearly cooling and heating electricity are turned back into the heat it moved, using its own ratings.
• Older and newer ratings are not mixed. A SEER or HSPF rating from before 2023 is put on the SEER2 and HSPF2 basis with the exact ratio of DOE's equivalent standard levels for its product class, from DOE's January 2017 direct final rule (82 FR 1786): for a split heat pump, 14.3/15 for SEER and 7.5/8.8 for HSPF. Those ratios translate standard levels, so applying them to one old unit is an approximation, and the rating note says so. With an Unknown basis the old rating is used as it stands, which makes the old unit look more efficient than it is, so the saving is understated.
• Electricity: cooling kWh = cooling need in Btu / (SEER2 x 1000); heating kWh = heating need / (HSPF2 x 1000), which equals dividing by a seasonal COP of HSPF2 x 1000 / 3,412.
• Backup heat: HSPF2 already includes the electric resistance heat a heat pump needs in DOE's moderate rating climate (Region IV), so the backup share is extra heat beyond that, supplied at 3,412 Btu per kWh, for both heat pumps.
• Yearly cost = electricity x electricity price + upkeep; the yearly saving is the old cost minus the new cost. Payback and present value follow the rules shared with the other replacement calculators, with nothing counted twice.

Calculation sequence

The spreadsheet first checks the inputs and finds each heat pump's ratings, the climate figures and the electricity price. It works out the heating and cooling need once, shared by both heat pumps, reduces each heat pump to the electricity it uses per million Btu of heating and of cooling, and from those computes the yearly electricity, costs and saving; the purchase cost, the paybacks, the present values and the year-by-year cash flow follow. The sensitivity table uses the same per-MMBtu figures, so it cannot disagree with the main result. Consistency checks, including that your bills are reproduced from the computed need on the bills route and that the discounted cash flow reaches the same net present value as the closed-form formula, run before the status is returned.

Outputs and interpretation

The results show the yearly heating and cooling need, the degree days used, and for each heat pump the ratings used (after any conversion), the yearly cooling and heating electricity, and the yearly energy and total cost; then the yearly saving in dollars and kWh, the net cost of the new heat pump, the simple and discounted payback, and the cost of each path. A note states where the need came from (your state's degree days and DOE use hours, or your bills) and another whether an old rating was converted.

The cash-flow table shows each year of the years compared: the cost of each path, the net benefit of replacing now, and its cumulative, discounted and cumulative discounted values. The sensitivity table shows the yearly saving with the heating and cooling need scaled by 0.50, 0.75, 1.00, 1.25 and 1.50, at the same multiples of the electricity price used.

A model card beside each listed pick shows the range of its ratings across the indoor units it is certified with, whether ENERGY STAR lists it as cold-climate, and its heating capacity. The calculator uses the lowest SEER2 and HSPF2 among those pairings, so it does not credit a better pairing than the one you may buy.

The first chart, “Cumulative net benefit of replacing now, by year”, shows Undiscounted and Discounted by year. The second chart, “Cost over the years compared”, shows Total and Present value by option. The third chart, “Running cost in year 1”, shows Cooling electricity, Heating electricity and Upkeep by system, stacked.

Validation and status logic

The workbook returns one status, chosen in this order: NOT VALID, then CHECK, then OK.

• NOT VALID names the first problem: an old-unit source or type that is not one of its options; a listed model that is not in its list or does not match the type chosen, or no federal minimum on file for that type, region and year made, in which case use the nameplate rating; a manual SEER or HSPF missing or outside its limits, or a rating basis that is not one of its options; a system size missing or outside 0.5 to 6 tons; the same problems for the new heat pump; a source of the need that is not one of its options, or a bills figure missing or outside its limits; the estimate needs degree days and your state has no figure and you have not entered your own; a backup choice that is not one of its options, or a backup share outside 0 to 1; no electricity price, or your own outside 0.01 to 2.00 dollars per kWh; a missing installed price, or one outside its limits; a money amount, the years compared, the price change, the discount rate or a life in years outside its limits. NOT VALID is a refusal, not a numeric answer: every figure reads zero and is withheld.
• CHECK accompanies a computed result that needs the stated review: the old ratings are the federal minimum for the year made; the old unit may be more efficient, so the saving may be overstated; an old SEER or HSPF rating with an Unknown basis, or with no conversion ratio for its class, is used as if it were SEER2 or HSPF2, so the saving is probably understated; a cold state (6,000 heating degree days or more), a new heat pump ENERGY STAR does not list as cold-climate, and no backup heat beyond the rating: the HSPF2 rating assumes a moderate climate, so real seasonal efficiency will be lower; on the bills route with no backup heat, the new heat pump's capacity at your coldest month's average temperature is below that month's average heating load; zero heating and cooling electricity on the bills route; no yearly saving, so there is no payback; the old unit's remaining life is shorter than the years compared, so read the end-of-life comparison.
• OK otherwise.

Assumptions and limitations

• Three labelled approximations. The figures behind them are DOE's, but how this calculator applies them is its own: DOE's standard-level ratios are applied to one old unit's SEER and HSPF; DOE's heating hours, which belong to a design heating requirement, are applied to your system's nominal size; and the national hours are scaled by your state's degree days. Your bills route avoids the last two, and a rating on the SEER2 and HSPF2 basis avoids the first.
• Not modelled: adjusting your bills for a mild or harsh year, solar and internal heat gains beyond what the degree-day base implies, humidity removal beyond the SEER2 test, and duct changes.
• A federal minimum is a floor, not a measurement. An old unit described by the year it was made may be more efficient than the minimum, so the saving may be overstated. Where the minimum changed during a year, the newer, higher minimum is used, which keeps the saving on the low side. Wear with age is not modelled.
• Inputs with no federal source are your assumptions: the installed price and any backup share beyond the rating. The cold-state threshold of 6,000 heating degree days is a design choice that only sets a warning.
• Alaska, Hawaii and DC. NOAA publishes no statewide degree-day normals for any of the three. DC uses Maryland's figures; Alaska and Hawaii each use one NOAA station normal, at the Anchorage and Honolulu airports, labelled as a single station. Your own degree days replace any state figure, and the bills route works everywhere.
• Prices. The installed price of the new heat pump is always your input; the workbook holds no price table. The opening example and each worked example carry a round illustrative price so that they compute, with the note: "Illustrative price for this example, not a quote or a current price. Prices vary: check current prices online or enter your own. Get a contractor quote."
• The default electricity price is a state average. Your own price from your bill overrides it.

Data and vintage

• Heat pumps: the ENERGY STAR certified air-source heat pump list (EPA), current certifications, one entry per outdoor unit sold in the US, each with the lowest SEER2 and HSPF2 among its certified indoor-unit pairings.
• Federal minimum ratings by year made and region: DOE energy conservation standards (10 CFR 430.32), with earlier editions of the Code of Federal Regulations (1997 and 2012) for the years before the current standard.
• Rating ratios and use hours: DOE's January 2017 direct final rule (82 FR 1786) for the SEER and HSPF level ratios, and the 2016 edition of 10 CFR 430.23 for the representative use hours.
• Climate: NOAA NCEI statewide heating and cooling degree-day normals for 1991-2020 (nClimDiv); the US figure covers the 48 contiguous states. NOAA calls these long-term averages rather than official normals, and its notes state neither the base temperature nor the weighting.
• Default price: EIA final 2025 average residential electricity prices by state (Form EIA-861).

Worked examples and prices

Prices are not part of the reference data: the price of the new unit is an input you set. The opening example and the five worked examples each use an illustrative price for the new unit, so that the example computes, and each says so: “Illustrative price for this example, not a quote or a current price. Prices vary: check current prices online or enter your own.”

Restrictions and non-computing states

The calculator enforces its numeric and choice limits before it accepts a result. A listed model that is not in its list or does not match the type chosen, a rating or quantity outside its limits, a missing installed price, and a missing electricity or fuel price where no default exists are refused by the workbook.

Errors and warnings

A request rejected by the page's input limits is not a computed result. A transport or service failure, a timeout or a cancelled run cannot establish a fresh workbook answer, and the last result stays on the page marked as out of date. Check your equipment's nameplate or AHRI certificate and your own bills before relying on a result for a purchase, and get a contractor quote for the installed price.

Sources and further reading

The calculator reads its model lists, its federal minimum ratings, its climate figures and its default energy prices from reviewed reference tables inside the workbook, with their version shown in the result details. Every table comes from a US federal source. The sources below publish the data and the rules the model applies. They do not endorse this calculator.

• ENERGY STAR data portal catalog (EPA) lists the EPA's certified-product datasets, among them the heat pump list used here (retrieved 2026-10-28).
• ENERGY STAR Certified Heat Pumps (EPA) lists certified air-source heat pumps by outdoor and indoor unit, with SEER2, HSPF2, heating capacity and a cold-climate flag (retrieved 2026-10-28).
• ENERGY STAR air-source heat pumps: information for partners (EPA) links the ENERGY STAR heat pump specification, whose criteria include the cold-climate designation shown on the model card (retrieved 2026-10-28).
• DOE energy conservation standards, 10 CFR 430.32 (eCFR) sets the SEER2 and HSPF2 minimums for heat pumps made from 2023, by region, and the SEER and HSPF minimums before them; earlier editions give the older levels (retrieved 2026-10-28).
• DOE test procedures, 10 CFR 430 subpart B (eCFR) defines SEER2 and HSPF2 under appendix M1, with HSPF2 rated for DOE's Region IV climate; 10 CFR 430.23, CFR 2016 edition (govinfo) gives the representative 1,000 cooling hours and 2,080 heating hours with the 0.77 adjustment (retrieved 2026-10-28).
• DOE direct final rule, 82 FR 1786, January 6, 2017 (Federal Register), Tables V-29 and V-30, gives the 2023 standard levels under the older and the newer test, whose ratios convert an older SEER or HSPF (retrieved 2026-10-28).
• NOAA NCEI, Climate Divisional Database (nClimDiv) publishes statewide heating and cooling degree-day normals, used here for 1991-2020 (retrieved 2026-10-28).
• NOAA NCEI, U.S. Climate Normals 1991-2020, station files gives the Anchorage and Honolulu airport normals that stand in for Alaska and Hawaii (retrieved 2026-10-28).
• EIA, British thermal units (Btu) gives 3,412 Btu per kWh (retrieved 2026-10-28).
• EIA, Detailed state data (Form EIA-861) gives the average residential electricity price by state, used here for 2025 (retrieved 2026-10-28).
• EIA, Residential Energy Consumption Survey 2020, state data gives typical space-heating and air-conditioning electricity per household by state for 2020, a cross-check for your own figures; it is not a value in the calculator (retrieved 2026-10-28).

This is an educational estimate of running and purchase costs for the equipment and prices you enter, not a product recommendation or a quote. Ratings are measured under federal test procedures, not in your home.