Training
23 October, 2026
Designing with low-load efficient heat pumps for Northwest builds
Low-load efficiency refers to how efficiently a heat pump performs when operating in mild conditions. To better understand the role low-load efficiency plays in heat pump performance, BetterBuiltNW spoke with leading experts Matt Christie and JJ Sawicki of the Advanced Heat Pump program, which supports innovations that improve heat pump performance and advance high-efficiency, variable-speed technologies.
Read on to learn more about the benefits of low-load efficient heat pumps and their suitability for diverse climate types across the Northwest.
BetterBuiltNW: Is low-load efficient heat pump technology a good fit across all climates in the Northwest?
Matt: “Yes. Low-load efficient heat pumps provide versatility for diverse conditions, ensuring reliable heating and cooling across a variety of climate types.
“West of the Cascades, where winters are generally milder, low-load performance is especially important. East of the Cascades, it’s important to select a heat pump that can both maintain capacity during colder weather and operate efficiently at lower loads during the rest of the season.
“Because homes across the Northwest experience a wide range of weather conditions throughout the year, low-load efficient heat pumps can provide energy savings in nearly every climate zone.
BetterBuiltNW: Are there data or real-life examples showing energy savings from low-load efficient heat pumps?
JJ: “Heat pump studies have been going on for decades, and recent research shows that low-load efficient heat pumps provide energy savings. The Low-Load Efficient Heat Pump Investigation from the Northwest Energy Efficiency Alliance estimated annual heating energy savings of roughly 3% to7% compared to average variable-speed heat pumps. Generally speaking, research results often reflect ideal conditions, so proper design is still key to achieving optimal efficiency from low-load efficient heat pumps.”
BetterBuiltNW: When a heat pump is sized for design conditions, will it spend most of its time operating at full capacity?
Matt: “No. Heat pumps, like all heating systems, are sized to fulfill the home’s design conditions. How much heat is needed to keep the house warm for the coldest 1% of hours of the year? For the rest of the winter, heating demand is typically much lower.
“But unlike other heating systems, cold climate heat pumps can be engineered to do two things very well. The first is to have much better efficiency while operating at low capacities. The second is to have good turn down, which is how low the heating output can get to meet those low-load needs without turning on and off. Frequent cycling can reduce efficiency and increase energy use, potentially causing utility bills to go up.”
BetterBuiltNW: How do you identify a low-load efficient heat pump?
JJ: “The NEEP cold climate air source heat pump list is a great resource that builders can use to determine which heat pumps have this technology.
“Look for the Coefficient of Performance (COP) at 47°F. Anything above 4.0 is a good heat pump. Anything above 4.5 is an even better heat pump. Anything above 5.0 is a phenomenal heat pump.”
Visit our website to learn more about advanced heat pumps and to find helpful resources to help expand your knowledge about the technology.