Matt Ferrell digs into saddle-style window heat pumps, units that sit on a windowsill like an air conditioner, install in about 30 minutes, and run off a standard 120V outlet with no electrical upgrades. The inverse-U shape drapes over the sill without blocking the window, and unlike a window AC, these units heat as well as cool. Because a heat pump moves heat rather than generating it, they deliver two to three times more heat energy than the electricity they draw. New York City is the proving ground. Under a city law targeting steep emissions cuts, its housing authority is replacing aging steam boilers across public housing, and these window units are the tool that makes that swap possible without tearing buildings apart or running new wiring.
The reason this reaches beyond New York is the form factor. Around 39 million Americans live in apartments, and renters have been largely shut out of the heat-pump shift because a conventional install means opening walls, which landlords will not fund and tenants cannot authorise. A windowsill unit removes all of that: no construction, no permission for structural work, and the resident controls their own temperature, with condensation managed internally so nothing drips down the building. Cities including Jersey City, Boston and Seattle are already eyeing bulk orders covering roughly 24,000 apartments. There is a tradeoff worth flagging that the pitch underplays: in many older buildings heat is bundled into rent, so shifting to these units moves that cost onto the renter's own electric bill, even as it hands them control they never had. For a landlord that is an incentive to switch, since it cuts the building's running cost, but a renter should go in knowing the bill follows the control.
The program behind it is specific. New York's Local Law 97, passed in 2019, requires buildings to cut emissions 40% by 2030 and 80% by 2050. The 2021 Clean Heat For All Challenge, backed by the New York Power Authority, NYSERDA and the city housing authority, put 263 million dollars toward new designs. Midea US won the largest share with 20,000 units, and its Packaged Window Heat Pump took an AHR Expo innovation award: it delivers 9,000 BTU per hour, holds a COP of 2.35 at 17 degrees Fahrenheit, runs from minus 13 to 113 degrees, and scores a 16 on the combined efficiency rating. Gradient supplies 10,000 units, with a COP of 2.60 at the same point, an R-32 refrigerant, and a rating of 10.8. By comparison, any boiler or electric radiator sits at a COP of 1 or less, so the efficiency gap is large. The authority wants units under 3,000 dollars, and Gradient estimates yearly running costs between 64 and 238 dollars. On the comparison between the two winners, Midea has the wider effective temperature range and the better combined efficiency rating, while Gradient claims a slightly higher mid-range COP and a quicker install of 15 to 20 minutes. The agencies involved say the combined draw of 30,000 units will not strain the grid.
Bottom line: The spec sheets are fine, but the breakthrough is the shape of the thing, not the numbers on it. Anything a renter can fit in half an hour without a landlord's sign-off opens a market traditional heat pumps never touched, and that is the part that could ripple out to every old apartment building in the country. The open question is price. At roughly 3,000 dollars a unit, the math only works because public bulk orders are driving volume, and the renter still absorbs the running cost on their electric bill. Federal rebates can soften that, but watch whether the per-unit price actually falls once production scales past these first 30,000.