top of page
  • Jacob Bourne

Heat Pump Technology Comes to Window AC Units

The demand for air conditioning is rising along with global average temperature, fueling a cooling crisis in which the cure exacerbates the ailment. Although life-threatening heatwaves are increasing the need for AC, the systems designed decades ago pump greenhouse gases more potent than carbon dioxide, namely Hydrofluorocarbons, or HFCs, into the atmosphere. However, new technologies are emerging to help society’s cooling needs while being friendlier to the planet.

Gradient window AC
Courtesy of Gradient

One startup, Gradient, has developed a window AC unit that uses heat pump technology coupled with a refrigerant that has a lower environmental impact. According to Gradient CEO Vince Romanin, the unit currently uses the R32 refrigerant; however, the goal is to use even more sustainable refrigerants in the future. The company is currently working with regulators to get approval for using these products in the U.S. Compared to other refrigerants, R32 has a low global warming potential and is entirely ozone-friendly.

"Air conditioning is one of the most essential amenities to keep people comfortable and productive in a warming world, but too many people are struggling with antiquated window AC units that are clunky, noisy, heavy and inefficient,” Romanin said. “Gradient offers a beautiful, intuitive design, a more efficient, sleek, quiet air conditioning experience, and climate-friendly refrigerants. Building a better air conditioner is one of the most effective ways to help people stay comfortable at home while helping to slash carbon emissions from HVAC systems."

Gradient designed its product to replace the traditional AC with a compact, easy-to-install unit that the company estimates will reduce 75% of carbon emissions. However, the exact decrease is dependent on the carbon intensity of the electrical grid where it’s operated and the kind of system previously used. Romanin said the goal is to achieve 100% carbon emissions reduction.

According to the Department of Energy, AC units in the U.S. release about 117 million metric tons of CO2 into the year annually. Compounding the problem, demand for AC could jump by 59% in U.S. residences by 2050.

Gradient’s window AC unit is currently in the beta testing phase, set to be available on the market in spring 2022. The price for the unit hasn’t yet been announced though it’s expected to be less expensive than comparable professionally installed units.

[Like what you read in The Carbonic? Help support climate journalism by donating ]

Incubated initially at Otherlab, a private R&D lab in San Francisco, Gradient was founded in 2017 by thermal scientists and executives from Tesla and Nest. So far, Gradient has raised over $13 million in venture funding from investors like Ajax Strategies, At One Ventures, Prime Coalition, Incite Ventures, Autodesk Foundation, Urban Us and Magic Hour. It also garnered more than $9 million in grants from the U.S. Department of Energy, California Energy Commission and California Strategic Growth Council.


Drop a line to for newsletter subscriptions, tips, questions or comments.

bottom of page