Advanced Heat Pumps Can Ease Grid Strain, But Details About Setup, Installation and Configuration Matter

Frigid winter temperatures can stress the grid, raise electricity demand and result in some surprising utility bills. One technology designed to help ease those pressures is the cold-climate heat pump. But it won’t do so automatically.

Heat pump aux heat can spike demand at inopportune times

When the outdoor temperature drops below ~35°F, traditional air-source heat pumps switch over to electric resistance auxiliary heat. Aux heat is needed to maintain comfort, but it can cause this typically efficient equipment to demand more power (maybe 5–10 kW per unit) than other forms of heating.

In a state where heat pumps are used in around 40% of households, that demand can add up quickly.

Cold-climate models are engineered to sustain their heating capacity even in bitter conditions (down to 5°F or lower), continuing to extract heat from outdoor air long after other systems call for support.

That’s a real benefit for grid operators and consumers alike. Capturing that benefit, though, isn’t guaranteed.

Real-world testing can reveal how to get the most out of cold-climate units

We’re studying how cold-climate heat pumps perform in the field through a pilot project with the North Carolina Electric Membership Corporation and Central Electric Membership Corporation. While the work is still in its early stages, here are questions we hope to answer:

• How do cold-climate heat pumps compare with standard air-source models (based on participants’ historical data) on overall energy use and coincident peak power demand, particularly during the 10 coldest winter hours and 10 hottest summer hours?
• How do occupants perceive the technology in terms of comfort, efficiency and usability?
• What can we learn from installation contractors regarding potential market barriers to deployment?
• How can this information guide future utility programs?

One early lesson: installation details matter.

Specifically, when a heat pump is first set up, its corresponding thermostat may default to turning on aux heat at around 35°F. This is known as the unit’s “cut-in temperature,” and it’s reasonable for a typical heat pump, which will lose heating capacity under those conditions.

But a cold-climate heat pump can operate efficiently at much lower temperatures, so if that cut-in value isn’t adjusted, aux heat will kick on unnecessarily and erase the potential grid and efficiency benefits. (To that end, another goal of ours is to gauge how easy it might be for users to accidentally change their cut-in temperature.)

Much more to come as the project continues, but ultimately, successful grid management depends on predictability. When resources or loads are implemented without a clear understanding of how they’ll behave, utilities — and their customers — might be anticipating an outcome that doesn’t become reality.