New York City and many similar 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 technology, these buildings are frequently too hot or too cold, but seldom just right.
A number of companies are now trying to fix that problem using clever horseshoe-shaped heat pumps. On the surface, they resemble window air conditioners, but they do not block the view and they can provide both heating and cooling. Gradient makes one of these heat pumps, and the company is now adding a new feature: in multifamily buildings, it can link every one of its window units together through a new software and 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 that need 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 two-story affordable housing complex in Tracy, California. It is also in discussions with colleges and universities, many of which have dormitories not built for hot autumn weather.
Older buildings often have a single electric meter, which can lead residents to overuse their heating or air conditioning. Nexus returns some control to building managers. They can set guardrails to prevent overuse of heat or AC—whether intentional or accidental—while still maintaining occupant comfort. In one case, a building manager set a heating limit at 78 degrees Fahrenheit, 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 that are reaching the end of their life, a common situation in New York City. As an added benefit, units that previously only had a steam radiator now get air conditioning, helping to future-proof them against worsening heat waves.
By installing a window unit rather than a minisplit system, retrofits can be completed in hours. They also do not require electrical upgrades, according to Romanin. In buildings with old electrical wiring that cannot support a full 12-amp load on a single outlet, Nexus can reduce the draw, said Mansi Shah, senior vice president of product and software at Gradient.
This strategy can also extend beyond the building. When the grid is overwhelmed by demand, such as on hot summer days, Gradient is developing a way to dial back its heat pumps while still maintaining comfort. By using building information and feedback from sensors in the heat pumps, the company hopes to predict which units can reduce air conditioning demand, like those on the shady side of a building. This sort of demand response can help the grid serve more heat pumps without requiring costly 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 electrons cheaper.”