DENVER (July 18, 2023) – A new study by Xcel Energy and the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) reveals the value and challenges of cold climate heat pumps, a key technology that could help support emission reductions of buildings. Among other things, the study evaluates the impacts of both extreme cold and high altitude on cold climate heat pump performance. The findings are the result of NREL experiments on two different cold climate air source heat pump configurations at NREL’s newly enhanced Thermal Test Facility in Golden, Colorado, and customer satisfaction results by Xcel Energy.

The study will inform Xcel Energy’s first-ever Clean Heat Plan, proposing solutions to meet Colorado’s Clean Heat Standard, which calls for a 22% reduction in greenhouse gas emissions by 2030 from the use of natural gas (from 2015 levels). Xcel Energy plans to file the Clean Heat Plan on August 1, 2023.

“The heat pumps tested performed well in the laboratory at cold temperatures, but their performance was impacted by the laboratory’s altitude above sea level between 5% and 12%,” said Jon Winkler, senior engineer at NREL. “We also learned that homes with restrictive ductwork need careful setup considerations when the heat pump blower uses a constant torque motor.”

Working with NREL, Xcel Energy is leading the nation in the exploration of opportunities associated with heat pump technology. Xcel Energy commissioned NREL to conduct performance testing at the enhanced NREL facility in Golden, CO. Through their work, NREL and Xcel Energy have determined:

  • Heat pumps are valuable technology to help reduce emissions from the building sector if combined with a low-emission electricity system, such as the system that Xcel Energy is constructing in Colorado
  • Adaption of the electric system to support large numbers of heat pumps will require careful planning and investments to meet customer load while maintaining reliability and affordability. 
  • Heat pumps will perform well at temperatures above 40 degrees F, but their performance degrades at lower levels
  • Most homes using heat pumps for heat would require additional backup heating, either gas-fired or resistance electric heating
  • Colorado’s altitude reduces heat pump performance by nearly 10% compared to heat pumps at sea level
  • Customers reported high positive feedback on heat pump installations including high marks for quality of work, professionalism and punctuality

NREL and Xcel Energy will install units and study the performance at higher altitudes this winter, in Leadville, CO, the state’s highest elevated town, for a more complete picture of the technology’s capabilities at high altitudes with extremely cold temperatures. Xcel Energy will continue to evaluate customer satisfaction through every phase of heat pump ownership and operation for customers participating in Xcel Energy’s heat pump pilot program. Participant homes represent a wide range of sizes and ages, important for understanding how these new systems will work in a variety of existing homes at various elevations.

“The results are unique for Colorado climate and elevations and that is important as we think about the entire customer experience for a new technology, as well as understanding how we can prepare the electric and natural gas systems for greater electrification,” Robert Kenney, President of Xcel Energy-Colorado. “We are strong supporters of beneficial electrification, and we are learning more about the performance of heat pumps for customers living in Colorado’s cold temperatures and high elevations. As grid planners, we need to learn as much as possible about the performance of electrification technologies and the impact they have on the grid. 

“Xcel Energy is exploring all options for achieving our net-zero vision for natural gas by 2050 as quickly as possible while maintaining reliability, affordability, and choice for customers. It is essential we chose the right balance of solutions that lower emissions, serve customers’ needs to stay comfortable in the winter, and maintain affordable energy service.”

Xcel Energy is incubating and scaling emerging technologies, like heat pumps, long-duration battery storage and clean hydrogen production to support the reliability and resiliency of the grid as the clean energy transition continues. Last summer, Xcel Energy joined the U.S. Department of Energy’s (DOE) Residential Cold Climate Heat Pump Challenge, partnering with Environmental Protection Agency (EPA), to demonstrate technology performance in cold climates and create incentives and products to accelerate customer adoption.

The Xcel Energy study on heat pumps is funded through Xcel Energy’s Demand Side Management budget, which is paid for by the Demand Side Management line-item on customer bills.

Xcel Energy currently offers heat pump rebates to income-qualified and non-income-qualified customers. To learn more about the Xcel Energy heat pump rebate, please visit XcelEnergy.com.

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About Xcel Energy

Xcel Energy (NASDAQ: XEL) provides the energy that powers millions of homes and businesses across eight Western and Midwestern states. Headquartered in Minneapolis, the company is an industry leader in responsibly reducing carbon emissions and producing and delivering clean energy solutions from a variety of renewable sources at competitive prices. For more information, visit xcelenergy.com or follow us on Twitter and Facebook.