The heat pump retrofit market just crossed a critical threshold. Gradient's new Nexus software transforms window-fit heat pumps from standalone hardware into integrated building climate systems—and that distinction matters. The company has moved beyond the engineer's problem (how do we fit efficient heating/cooling into old buildings?) into the operator's reality (how do we manage comfort, energy use, and grid demand simultaneously across hundreds of units?). For building managers and property owners watching aging boilers reach end-of-life, this opens a retrofit window that closes once installation friction becomes irrelevant again.

New York City's problem is America's problem in miniature: buildings that were cutting edge when steam boilers were installed are now either freezing or sweltering, with no middle ground. There are millions of aging multifamily buildings across the country built in an era when climate control meant massive central systems that heated or cooled everything equally. These structures sit in retrofit limbo—the boilers work, just barely, but replacement means weeks of construction chaos, six-figure electrical upgrades, and tenant resistance that kills most retrofit proposals before they begin.

This is where Gradient enters. The company makes window-fit heat pumps, which sound like air conditioners but work both directions and don't block the view. That's clever hardware engineering. But hardware alone doesn't cross the inflection point from "niche solution for early adopters" to "standard retrofit path for building operators." The inflection happens when that hardware talks to building management software.

Gradient's Nexus software does exactly that. In multifamily buildings, it links every window unit together into a coordinated system. The company shared exclusive details with TechCrunch about how this reshapes the retrofit calculation.

Start with installation. A traditional minisplit heat pump requires a technician to run refrigerant lines through walls, punch holes, install condensers. That takes days and requires careful planning. Gradient's window units install in hours—basically the effort of mounting a window air conditioner. For multifamily buildings where you're installing 50, 100, or 200 units, the difference between days and hours per unit compounds into weeks of labor saved. "Multifamily buildings are an ignored sector," Vince Romanin, Gradient's chief technology officer, told TechCrunch. "It's a place where we can do better for the user."

Then there's electricity. Old buildings have old electrical systems designed when the peak load was a few stove burners and some lights. Installing traditional heat pumps might require a full electrical service upgrade—and that costs $50,000+ before you even add the HVAC equipment. Gradient's units draw less power individually, and Nexus can distribute the load across multiple units over time, using their sensors and building information to shift demand. In buildings where the electrical panel can't handle a full 12-amp load on a single outlet, Nexus reduces the draw intelligently. One less barrier between retrofit proposal and tenant acceptance.

But the real inflection point sits in building operations. Old multifamily buildings typically have one electric meter serving the entire structure. That creates a tragedy-of-the-commons scenario where tenants have no price signal for HVAC usage—overheating in winter or over-cooling in summer costs them nothing directly. Building managers watch energy consumption spike and have almost no leverage to control it without making tenants uncomfortable.

Nexus inverts that dynamic. Building managers set guardrails—heating limit at 78°F, cooling at 72°F, for example. Tenants still control their own comfort within those boundaries, but they can't push the system past the operator's threshold. Gradient shared one real-world result: a building manager set the heating limit at 78°F, and energy consumption dropped 25% the next day. That's operational leverage. That's why building managers care, not just why engineers do.

This matters for timing. Building owners targeting energy retrofits face regulatory pressure that's accelerating. New York City's Climate Mobilization Act requires buildings over 25,000 square feet to hit emissions targets by 2030—and those targets are tight enough that aging buildings need to move. California's Title 24 building standards keep shifting toward electrification. Massachusetts requires stretch energy codes. The window for retrofit decisions is real, and it's closing. A building owner looking at boiler replacement this year needs a solution that installs fast, doesn't blow the budget on electrical work, and actually cuts energy usage. Gradient's combination of hardware (window-fit, fast installation) and software (coordinated control, demand response) addresses all three.

Gradient has already moved beyond concept. The company has worked with the New York City Housing Authority to install units in public housing. It ran a pilot in Tracy, California, in affordable housing. It's talking with universities—particularly relevant because dorms built in the 1960s and 1970s typically have no air conditioning, which becomes a liability during heat waves. Each of these deployments generates real data about energy savings and building performance.

The next inflection point to watch is grid integration. Gradient is working on demand response capabilities—when the grid is overwhelmed on hot summer afternoons, the system can dial back AC in units on the shady side of the building, maintaining comfort while reducing peak demand. That's valuable to utilities. It might eventually become so valuable that utilities fund part of the retrofit as a grid reliability investment, the same way they do for smart thermostats and time-of-use programs today. When utilities fund retrofit adoption, the market becomes something else entirely.

Romanin puts it directly: "There's a lot of people who said when we electrify everything, the grid won't handle it. I think it is very possible to electrify everything and make the grid better, make the grid's job easier, and make electrons cheaper." That's the larger inflection point underneath—electrification isn't a consumer choice anymore, it's infrastructure policy. The companies that make electrification operationally feasible for building owners will shape how quickly that transition happens.

Gradient's Nexus software marks the moment retrofit adoption shifts from engineering solution to operational business case. For decision-makers at building management companies, property owners, and facility operators, the timing window is specific: if boilers are reaching end-of-life this year, the retrofit calculation has shifted in favor of electrification. Builders should track this closely—the combination of fast installation and intelligent controls means retrofit margins improve significantly compared to traditional approaches. Investors watching the heat pump retrofit space should note that software coordination is becoming the competitive moat, not hardware efficiency alone. Professionals in climate tech and building operations need to understand demand response and grid integration, not just HVAC mechanics. The next threshold to monitor is utility-funded retrofits—when grid reliability benefits make heat pump installation profitable for building operators without waiting for energy savings, the retrofit market accelerates exponentially.