New York City and others like it are full of old buildings that are generally fine, except that they are not very comfortable to live in. Built at a time when large boilers were the latest technology, the buildings were often too hot or too cold, but rarely just right.

There are companies trying to correct that with the clever horseshoe shape heat pumps. Superficially, they are similar to window air conditioners, except that they do not block the view and they can heat as well as cool.

Gradient made one of the heat pumps, but now it adds a twist: In multifamily buildings, it is possible to connect each of the units to its window. The startup shared with TechCrunch exclusive details about the new Nexus software and services.

“Multifamily buildings are an overlooked sector,” Vince Romanin, Gradient’s chief technology officer, told TechCrunch. “This is an area where we can do better for the user.”

The startup usually focuses on older buildings that need an HVAC upgrade. Gradient is working with the New York City Housing Authority to install its heat pumps in public housing, and it’s running a pilot in Tracy, California, in a new two-story affordable housing complex. It also speaks to colleges and universities, many of which have dorms that aren’t built with the hot fall weather in mind.

Older buildings often have an electric meter, which can tempt residents to overuse their heating or air conditioning. Nexus gives some control back to building managers. They can put up guardrails to prevent people from overusing the heat or AC – whether on purpose or otherwise – while allowing them to be comfortable. At one point, a building manager set the heating limit at 78˚ F, and the next day energy consumption dropped by a quarter.

Romanin says Gradient’s heat pumps are the “lowest cost option” for older buildings with boilers nearing the end of life, a common occurrence in New York City. As a bonus, units that previously only had a steam radiator now get air conditioning, future proofing the units against worsening heat waves.

By installing a window unit instead of a minisplit, changes can happen within hours. They also don’t need electrical upgrades, Romanin said. In buildings with old electrical wiring that can’t support a full 12 amp load on an outlet, Nexus can reduce the draw, said Mansi Shah, senior vice president of product and software at Gradient.

That strategy can also extend beyond the building. When the grid is overwhelmed with demand, which can happen on hot summer days, Gradient works in a way to dial back its heat pumps while maintaining occupant comfort. By using information about the building along with feedback from the heat pumps’ sensors, the company hopes to predict which units can reduce their air conditioning needs, such as those on the shaded side of a building. That kind of demand response helps the grid serve more heat pumps without requiring expensive upgrades.

“There are a lot of people who say that if we electrify everything, the grid won’t manage it,” Romanin said. “I think it’s very possible to electrify everything and make the grid better, make the work of the grid easier, and make electrons cheaper.”