Here’s a burning question on the minds of . . . me, a few friends of mine, and possibly you if you’ve stumbled across this blog post: if you spend the money to install a heat pump, will that save you money on your monthly energy bills, and if so then how much?

I’m assuming if you’ve gotten this far you know that switching your home from fossil heat to an electric heat pump powered by carbon-free energy is a key step in “electrifying everything” and reducing your climate footprint. If not, go ahead and check out Step Two on this site — along with Step Three, more on that below. But even if doing your part to address climate change is on your priority list, it’s not crazy to want to understand how a heat pump will fit into your climate budget over the lifetime of the investment — about 15 years on average, according to the U.S. Department of Energy.

As you’re looking to switch to a heat pump for home heating, you may well run into budget concerns regarding: (1) up-front installation costs — the sustainable consumer website Carbon Switch has done a recent survey on what those might look like; and (2) unfortunately, some HVAC contractors who will tell you it’s much cheaper to use natural gas and that you’ll break the bank with electric heating. There are new options coming to deal with issue #1, as companies like Sealed develop approaches that let you install a heat pump without an initial lump-sum payment and instead cover the cost out of your home energy savings over time, and affordable utility or government financing programs pop up. Regardless, many people want to figure out the real deal on issue #2: whether a big investment in a heat pump will reduce your heating and cooling costs in the long run.

It turns out that’s harder than it might seem. I thought I’d dash off this blog post in a day or so and pat myself on the back, but it took a while longer than that! The good news is that there are tools you can use to get a handle on potential operating costs for a heat pump once you know how to use them — which I’m about to help you out with. And even more importantly, there are ways you can reduce those costs to maximize your bill savings and free up more of your budget for other steps to reduce your climate footprint. (Or at least a nice dinner out on the town, you deserve that for installing a heat pump!)

Starting with the basics, there are five main factors that will affect your potential savings from using a heat pump:

• Existing HVAC equipment size and efficiency

• Heat pump size

• Heat pump efficiency

• Climate (i.e., how many hours of the year you’ll likely be running the heat pump for heating/cooling)

• Fuel/electricity costs

That’s not too complicated, right? Surely someone has put together a calculator where you can enter all the right variables and have it spit out an estimate of potential bill savings?

Well, despite my best efforts I could not find one consolidated tool where you could run all the numbers in one fell swoop. If you come across one, let me know and I’ll send you some free Climate Smart Handbook swag. (I don’t actually have any swag, but I’ll make some just for you!) If you’re the kind of person with the technical skills to make a calculator and put it out there for the world to use, I’ll have to think of something even better — I’m done having kids, otherwise I’d name the next one after you. Maybe a pet?

For now, there are online cost calculators available from the HVAC industry that you can put together to get the whole picture. I’ve picked ones that I found relatively user-friendly, but I’m open to suggestions on alternatives. Drumroll please…..

• Existing cooling costs: https://www.seerenergysavings.com

• Existing heating costs: https://www.seerenergysavings.com/afue-savings-calculator (just enter the information for your “current system”)

• Heat pump heating and cooling costs: https://www.pickhvac.com/heat-pump/basics/cost-to-run

How do you actually use these? In each one, you’ll be able to enter information about the size and efficiency of your existing HVAC equipment or the heat pump model you plan to install as appropriate; where you live; and the price you pay for energy. (Check the fine print at the bottom of the SEER calculator for those last two items.) Note that calculating the applicable energy price may require some unit conversions, which is not too hard thanks to the Internet — here’s one calculator from the U.S. Energy Information Administration to make it easy. Once you’ve pulled all the data together, you should have a somewhat tailored estimate of how much you’re spending on heating and cooling each year currently based on your local climate and energy costs, and how much you’d spend if you switch to a heat pump.

The appliance and geographic information should be pretty straightforward, you’ll just need to ask your HVAC contractor (or look at the actual equipment) the tonnage and SEER rating for your current air conditioner; the BTU input and AFUE efficiency rating for a furnace; and the tonnage, SEER rating, and HSPF efficiency rating for whatever heat pump you plan to install. Of course make sure you have a good contractor first, who won’t stick you with an oversized heat pump without analyzing your home’s energy usage and seeing if it makes sense to also invest in some air sealing or insulation — more on that in Steps Zero and Two if you need a refresher.

For the cost of energy, I recommend the easy approach of focusing on an apples-to-apples comparison of fuel costs for each HVAC technology without worrying about the intricacies of your entire bill. To do that, you’ll look solely at whatever fuel supply or generation rate you pay for each type of fuel on a per-unit basis. (If you have trouble identifying that on your bill, then I’d call the utility to ask.) In case it’s not obvious, if your natural gas or electricity price varies seasonally (i.e., higher in winter or summer), then make sure to use the winter price for heating costs and summer price for cooling costs. Of course, if you do want to go the more complicated route of including every “volumetric” charge on your bill that varies based on your usage, then have at it!

Hopefully at the end of this process you’ll get some rough approximation of whether switching to a heat pump will save you hundreds of dollars a year for the next 15 years (entirely possible if you currently use heating oil or propane); won’t move the needle much on your annual energy costs; or will raise your bills as you shift from a fuel like natural gas to electricity. Will those projections be precisely accurate? Of course not, for a number of reasons. Energy prices change — we’re all living that reality now. Your house may have specific characteristics that make it easier or harder to heat and cool than these calculators assume. The weather might be particularly mild or severe in a given year. You might switch to a heat pump as part of “electrifying everything” and save a ton of money on fixed monthly charges from your natural gas utility. You may have solar panels that help you save money running a heat pump on hot summer afternoons. These factors all make it difficult to say for sure how your utility bills will turn out if you install a heat pump.

So why have I led you down this garden path? Don’t be mad, I have two actual reasons:

1. I’m hopeful that, at least for some of you, having reality-based numbers in hand to get a directional sense of the bill impacts of a heat pump is helpful in dispelling the fear from hearing scary stories about paying sky-high heating bills in the winter. Those types of anecdotes often date back to well before the current generation of heat pumps that can work well even in cold climates, without switching to more expensive “emergency” or “back-up” heating modes. The reality is that modern heat pumps are ready to use (hopefully carbon-free) electricity to heat and cool your home far more efficiently that traditional A/C units and furnaces.

2. Having an estimate of how much an electricity you’ll use with a heat pump can also give you a good idea of how much extra you can save — beyond simply switching to more efficient HVAC technology — by taking advantage of programs that offer discounted rates or bill rebates for using electricity at “off-peak” times when demand is lower. If you’ve read Step Three, you know that these types of time-varying rates and peak rebate offerings are rapidly spreading across the country, and with a smart thermostat you can easily sync a heat pump to leverage them for cost savings. It’s definitely worth checking out options in your area; getting even a few cents off your rate per kilowatt-hour can end up lowering your bills by hundreds of dollars a year. And if there’s nothing available right now, check out my page on getting involved in the policy world and you might be able to change that.

Bottom line: should you jump on the heat pump wagon because you know you’ll be guaranteed utility bill savings? Not necessarily. If you’re looking at a heat pump and concerned about the installation costs, should you check on whether you might also get a fair bit of savings for the next 15 years? Absolutely. In the immortal words of Yogi Berra, “If you don’t know where you are going, you might wind up someplace else.” When it comes to a heat pump, it’s definitely possible to get an idea of where you’re going — and avoid being scared off the road toward reducing your climate footprint.