The Transition to Heat Pump Window Air Conditioners Has Begun

A sea change in motor technology will soon wash away the era of noisy, polluting units.

Eight years ago, I predicted in “ The Celestia Project ,” that traditional window air conditioning would be banned by 2027. It looks like I had the transition timing about right, but the cause wrong. It isn’t public outrage that’s sending outdated air conditioners to the appliance afterlife, nor a sudden surge in corporate responsibility. It’s upgraded technology.

The biggest change has been the introduction of variable speed inverter motors that respond precisely to the demand for heat exchange from the compressor. This finesse results in a device that is about 30 percent more efficient at producing the same BTU of cooling as a non-inverter predecessor.


Out with the Old. New heat pump air conditioners may look like the old ones, but they’ll function much more efficiently, heating as well as cooling.

Air Conditioners Versus Heat Pumps

There’s some confusion in terminology. Most of these new window units should not be called heat pumps (yet). They transfer heat with compressed refrigerant, yes, but only in one direction. 

A heat pump, in contrast, has the capability to heat as well as cool, by means of a reversing valve that changes the direction of flow of compressed liquid refrigerant. This is an important detail, because some of the new window units being sold as heat pumps advertise that they also provide heat.

They supply this “supplemental heat,” however, with old fashioned electric resistance, not compressed refrigerant. That’s an inefficient form of space heating.

The good news is that true heat pump models of window units are imminent. When they do hit the market (probably next year), along with saving energy for cooling, they will offer far better efficiency than resistance-based electric heating .

A Big Boost on Cooling Efficiency

Several companies have already taken the first step toward heat pump window units by releasing cooling-only products with variable speed  inverter motors. I’ve seen products touting this tech upgrade from LG, Frigidaire, Amana and GE Profile, and GE-owned Midea.

None of these new products, however, offer full two-way heat pump technology.

You can quickly glean this from the retail pricing of the units. Most of the new cooling-only models can be had for about $500. Based on how DIY heat pumps such as Mr. Cool are priced online, I would expect full heat pump units to start at closer to $800, when they become available. 

Hopefully that number, too, will drop rapidly if the units proliferate. It’s still a lot cheaper and less labor intensive than installing a mini split system with a separate compressor.

And prices have dropped like a stone over the past year. I paid almost $700 for a 10,000 BTU U-Shaped Inverter Window Air Conditioner from Midea (a GE company) unit a year ago, and that same unit now sells for about $450.

Frigidaire has a new 8,000 BTU model, the FHWH082WA1 , with supplemental heat, and GE Profile now the 10,000 BTU model AHTR10AC , which retails for about $525. They claim that it’s currently the most efficient window air conditioner in the U.S., operating at 15.7 CEER. That translates into 41% more energy efficiency than a standard model. LG now offers a 10,000 BTU LW1022IVSM , in a similar price range.

Along with better performance, the big perk you get with these inverter-driven cooling products is a major reduction in noise. Some of the U-shaped units especially operate at near whisper-quiet levels, because the compressor fan is kept isolated outside the building.

Coming Soon: A Heat Pump for Your Window

Cooling efficiencies 30 to 41 percent above the old clunker in your window is a welcome upgrade, but it’s just phase one of the great window air conditioner replacement.

At the Builder Show in Vegas this year, I saw more than one self-contained heat pump system that offers a simplified installation of a single hole through the wall of the house.

I’d be willing to bet that every major HVAC manufacturer has its R&D people frantically working on full heat pump models for window HVAC. They know they’ll be competing with smaller companies who hope to catch the wave early.

A lot is happening quickly. Midea, for instance, has been contracted by the City of New York to provide 20,000 full heat pump window units for public housing. They’re in development to produce easy-install window products that can retrofit easily and greatly improve HVAC efficiency.

On the Horizon: Solar Heat Pump Models

The reason sustainability advocates like heat pump technology so much is closely related to the sourcing of energy. Many heat pumps, especially on the scale of window-sized units, with variable speed inverters, can adapt easily to renewable energy.

A few months ago, we tested a direct-run solar powered mini split that functions smoothly and efficiently. I expect that within a year or two, we’ll begin to see solar powered window heat pumps that run on sunlight all day, then switch automatically to grid power.