New York City and other urban centers are filled with old buildings that are structurally sound but often uncomfortable to live in. Constructed in an era when massive boilers were cutting-edge, these buildings tend to be too hot or too cold, but seldom just right.
Several companies are working to solve this problem using clever horseshoe-shaped heat pumps. On the surface, they resemble window air conditioners, but they don’t block the view and they can both heat and cool a space. One company, Gradient, makes such a heat pump and is now introducing a new feature: in multifamily buildings, it can link every one of its window units together through new software and a service called Nexus.
“Multifamily buildings are an ignored sector,” said Vince Romanin, chief technology officer at Gradient. “It’s a place where we can do better for the user.”
The startup primarily targets older buildings in need of HVAC upgrades. Gradient has worked with the New York City Housing Authority to install its heat pumps in public housing and ran a pilot in a newer affordable-housing complex in Tracy, California. It is also in discussions with colleges and universities, many of which have dorms not designed for hot autumn weather.
A common issue in older buildings is a single electric meter for the entire property, which can lead residents to overuse heating or air conditioning. Nexus returns some control to building managers. They can set guardrails to prevent overuse—whether intentional or accidental—while still maintaining occupant comfort. In one case, a manager set a heating limit, and energy consumption dropped by a quarter the next day.
Romanin stated that Gradient’s heat pumps are the lowest-cost option for old buildings with boilers nearing the end of their life, a frequent situation in New York City. An added benefit is that units which previously only had steam radiators now get air conditioning, helping to future-proof them against worsening heat waves.
Installation is relatively simple. By using a window unit rather than a minisplit system, retrofits can be completed in hours and typically do not require electrical upgrades. For buildings with older wiring that cannot support a full electrical load, Nexus software can reduce the draw from individual units.
This strategy can also benefit the broader electrical grid. During periods of high demand, such as hot summer days, Gradient is developing a way to dial back its heat pumps while maintaining comfort. By using building data and feedback from sensors, the system can predict which units can temporarily reduce air conditioning demand, like those on the shady side of a building. This type of demand response can help the grid accommodate more heat pumps without needing costly infrastructure upgrades.
“There’s a lot of people who said when we electrify everything, the grid won’t handle it,” Romanin said. “I think that it is very possible to electrify everything and make the grid better, make the grid’s job easier, and make electricity cheaper.”