Heat Pumps

To estimate the number of homes that currently heat with heat pumps, we use heat pump shipment data published by the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), along with equipment and housing stock data from the most recent Energy Information Administration’s Residential Energy Consumption Survey (RECS), and equipment lifetimes from NACHI. 

We use RECS data from 2005, 2009, 2015, and 2020 to anchor our estimate of the number of US housing units (stock)  that use electric heat pumps as their primary heating source. We extrapolate the stock for years in between RECS survey years (prior to 2020) using heat pump shipment data from AHRI. We then calculate heat pump sales by adding the increase in stock to the estimated number of heat pumps which need to be replaced every year. We use this data to translate AHRI shipment data from 2020 to 2024 into sales. We allocated those sales to end of life replacements and increases in stock. We forecast 2025 stock by averaging the annual stock increases from 2020 to 2024 and projecting forward by one year.

Heat Pump Water Heaters

To estimate the number of homes that use heat pump water heaters, we use sales data from ENERGY STAR, equipment lifetime data from NACHI, and data from the Advanced Water Heating Initiative.

We estimate annual sales from 2009 to 2023 as the totals from ENERGY STAR Annual Unit Shipment Data reports. To estimate the number of water heaters in use in homes, we use average lifetimes from NACHI to allocate sales to new stock and end-of-life replacements, assuming no existing heat pump water heaters in use prior to 2009. We use the Advanced Water Heating Initiatives sales forecasts to project sales and stock for 2024 and 2025. 

Electric Ranges

We estimate the sales and stock of induction and electric ranges using analysis from Grand View Research, AHAM, and RECS.  

We use RECS data on the number of households that either (1) use an electric or induction range, or (2) do not have a range and have an electric or induction cooktop, to estimate the number of households using electricity for their cooking in 2015 and 2020. We assume that the number of electric resistance ranges and cooktops remains effectively flat from 2020 to 2025, based on the trend from 2015 to 2020. We then allocate estimated induction sales data provided by AHAM and Grand View Research to new installations and to end-of-life replacements. Estimates for 2025 sales are from Grand View Research. 

Electric Vehicles

We collect electric vehicle sales numbers from the Bureau of Transportation Statistics for 2016 through 2023 and from Kelly Blue Book (KBB) for 2024. Projections for 2025 electric vehicle sales are from Cox Automotive’s 2025 outlook. We quantify the number of electric vehicles on the road based on Department of Transportation driver registration data from 2016 to 2023. Estimates for 2024 and 2025 stock are calculated by adding previous years’ new EV sales to the prior stock number. A calculated stock-to-sales ratio for each year estimated that the majority of new electric vehicle sales were directed toward new stock, rather than end of life replacements. Our calculations only include battery powered EVs and do not consider hybrid or plug-in hybrid vehicles.

Rooftop Solar

We sourced sales data for 2016 to 2020 from the Lawrence Berkeley National Laboratory’s Tracking the Sun Tool while data for 2021 to 2023 are provided by Ohm Analytics. Projections for 2024 and 2025 are derived from market estimates by SEIA and Ohm Analytics. Figures for the number of households currently using rooftop solar come from the National Renewable Energy Laboratory's Spring 2024 Solar Industry Update for 2016 to 2023. Estimates for 2024 are calculated by adding previous years’ sales to the prior stock number. A calculated stock-to-sales ratio for each year estimated that the majority of new rooftop solar sales were directed toward new installations, rather than end of life replacements.