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This new tool makes it easier to crunch the costs of energy upgrades

Heat pumps, solar panels and EVs can save households money and slash emissions. A new calculator from RMI helps contractors figure out by how much.
By Alison F. Takemura

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A graphic of a home with solar panels, an EV, EV charging, an air-source heat pump, a heat-pump water heater, and more.

A new free tool for contractors and other energy professionals aims to pin down the economic and climate benefits of electrifying homes and commutes — a calculation typically hard to come by.

While figuring out the upfront costs of upgrades such as heat pumps is routine for energy pros, estimating their impact on emissions or on a household’s utility bills is much more challenging. An accurate forecast depends on a dizzying array of factors, including equipment performance and efficiency, the local climate, home insulation and air-tightness, and future energy prices.

The Green Upgrade Calculator, unveiled by climate think tank and nonprofit RMI last week, uses these variables and more to estimate the lifetime costs and emissions savings of common home-decarbonization upgrades, versus those of conventional fossil-fuel replacements. The calculator covers rooftop solar, home batteries, air-source heat pumps, heat-pump water heaters, induction stoves, electric vehicles, and e-bikes, as well as weatherization, electrical panel, and health and safety updates, like asbestos remediation. Users can mix and match multiple upgrades at once to see their cumulative cost or climate impacts. (Canary Media is an independent affiliate of RMI.)

Roughly 115 million U.S. homes still need to ditch fossil-fuel equipment to meet national emissions reduction targets. Currently, the rate of climate-friendly retrofits is estimated at less than 1 percent of the nation’s housing stock per year — far too slow, according to RMI. To turbocharge the transition, the Biden administration is releasing $8.8 billion in home energy rebates, with the first states expected to start rolling out programs in the coming months.

The calculator aims to help pick up the pace on retrofits by enabling contractors to more clearly articulate benefits to homeowners.

We’re excited about [the tool]. Honestly, I think we’re gonna try to use it on every project,” said Damian Hodkinson, VP of business development at home contractor Halco Energy. His company, which serves upstate New York, beta-tested the RMI calculator.

Charts showing cumulative curves over 20 years of cumulative emissions & costs of green upgrades vs. conventional upgrades.
RMI’s Green Upgrade Calculator provides an estimate of the cumulative cost and emissions of clean-energy home upgrades (in this example: rooftop solar, a ducted air-source heat pump, and a heat-pump water heater), compared with those of traditional replacements (in this example: ducted central air conditioning, a fossil-gas furnace, and a fossil-gas water heater). Though the example’s upfront costs are higher for the green upgrades, the lifetime costs are reduced by at least $22,000 and the lifetime emissions by 44 million tons of CO2 equivalent. (RMI)

The two charts — one on cost and one on emissions reductions — that the calculator generates are powerful,” Hodkinson said. People tend to equate dollar savings with CO2 emissions impacts, he explained. But those aren’t the same, and in some cases, green upgrades save energy but result in higher utility bills. In those scenarios, he said, the tool is very honest.” A customer might think, “‘The dollar impact isn’t as big as I thought. But wow, look at that carbon impact.’”

Calculator in action

RMI developed the tool in partnership with seven other organizations: Abode Energy Management, Arcadia, the Electrification Coalition, New Buildings Institute, Northeast Energy Efficiency Partnerships, Pacific Northwest National Laboratory, and Solar United Neighbors. Since the calculator’s debut last week, nearly 2,000 individuals have used it to perform their own analyses, said Ryan Shea, the lead developer of the calculator and a building-decarbonization expert at RMI

The tool was designed for energy professionals, but curious consumers can try it as well. 

To use the calculator, simply enter in basic information: home location, type, year built, size, and (if considering an EV) current vehicle type. Then select all the desired green upgrades, as well as what the conventional, typically fossil-based replacements would be. The process takes less than five minutes.

screenshot that includes entry fields of zip code, 'what is the type of home?', 'when was the home built?', etc.
Some of the required inputs for RMI’s new calculator for users making climate-friendly upgrades to their home and vehicle. (RMI)

To get more accurate results, users can add more detail about their (or their customers’) home, car, and desired upgrades, such as their typical monthly energy bill, the EV model they want, the size of the heat pump they’re eyeing, and whether they’re financing or paying cash upfront.

The tool incorporates a bevy of data sources to calculate lifetime costs and emissions for the selected clean-energy upgrades. It leverages an hourly energy-use model, utilizing data from the National Renewable Energy Laboratory (NREL) and the U.S. Energy Information Administration. It harnesses real-time electric utility rates through Arcadia’s Signal tariff database, which includes time-of-use rates. It automatically accounts for state and federal incentives — including the torrent unleashed by the 2022 Inflation Reduction Act. And with NREL’s Cambium dataset, it models the hourly greenhouse gas emissions of state electric grids. 

Shea said that RMI hasn’t yet calculated the standard error for every analysis the tool can run, but in the cases where RMI has compared estimates with analysis from HVAC pros, the results are similar.

The data-rich integration and ability to override any upgrade’s technical details or upfront costs in favor of actual project quotes are what set the tool apart from the free options geared toward consumers, such as ones from Rewiring America, Canopy, Wildgrid, and others, Shea said.

Fee-based tools similar to RMI’s calculator do exist, though. Software from startup Radiant Labs, a member of the RMI-cofounded accelerator Third Derivative, also calculates lifetime upgrade costs and emissions savings. To refine its modeling, the software harnesses more data sources, such as monthly utility-bill, permitting, real estate, and satellite data, according to CEO and cofounder Adam Stenftenagel.

Importantly, though, to Shea’s knowledge RMI’s new calculator is the first free one with such a high degree of customization, he said. That should make it an easier entry point for contractors just getting started in the electrification space. 

The calculator can also be used by analysts to model the effects of policy, from the federal level down to the local, Shea said. For example, RMI found that switching all single-family homes in New York to electric heat-pump water heaters would save homeowners $268 per year on average. Statewide, those savings would add up to $741 million. 

Chart titled: annual energy bill savings switching to a heat pump water heater in New York. Largest savings from resistance

Like any tool, the Green Upgrade Calculator has its limitations. In its current state, it can’t address multifamily buildings and doesn’t include ground-source heat pumps — aspects Shea said the team may add into the next version. 

For Hodkinson of Halco Energy, RMI’s calculator is simple, quick, and valuable. He feels more confident in the accuracy of its cost and emissions estimates than those of most other tools he’s used; it accounts for more variables and can be fed more specific information, he said, calling it a missing piece for us.”

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Alison F. Takemura is staff writer at Canary Media. She reports on home electrification, building decarbonization strategies and the clean energy workforce.