Electrifying room heating and cooling without disruptive building retrofits.
Photo credit: Gradient / gradientcomfort.com
Gradient is a heating-and-cooling company founded in 2017 by thermal scientist Vince Romanin and building-electrification advocate Saul Griffith. Originally incorporated as Treau, the company makes saddle-style window heat pumps that place the compressor outdoors while preserving light and window use. Its All-Weather 120V model supplies heating and cooling from a standard outlet and is designed for multifamily buildings where panel upgrades, refrigerant piping, or major interior construction can make conventional heat-pump retrofits difficult.
Gradient sells equipment and services to housing authorities, multifamily owners, schools, senior housing, hotels, and other building operators. It also offers Nexus, fleet-management software that lets operators view telemetry, establish temperature limits, coordinate units, and manage power demand. The company's public-sector work includes the New York City Housing Authority's Clean Heat for All program and Clean Heat Rhode Island; deployments in Boston, Detroit, Washington, D.C., and Providence demonstrate use beyond consumer trials.
Product generations must be distinguished when discussing refrigerants. Gradient's original consumer heat pump used R-32, an HFC with substantially lower global-warming potential than R-410A but not a natural refrigerant. The newer cold-climate All-Weather 120V product uses R-290 propane, which has very low global-warming potential but requires charge limits and safety engineering because it is flammable. Energy and emissions performance also depends on climate, controls, building envelope, displaced equipment, and the electricity mix.
Gradient's principal impact pathway is enabling heat-pump adoption in buildings that are expensive or disruptive to retrofit with mini-splits or central systems. Room-by-room 120V installation can avoid new refrigerant lines and, where capacity allows, electrical upgrades. Replacing resistance heat or fossil-fuel combustion with an efficient heat pump can reduce delivered energy and operational emissions, while cooling access can improve resilience during extreme heat. Central fleet controls may further reduce wasted runtime.
The benefits are site-specific. A heat pump does not guarantee lower bills or emissions when tariffs, poor envelopes, occupant behavior, backup heat, or carbon-intensive electricity work against it. Gradient's older R-32 and newer R-290 products have different refrigerant impacts, and neither eliminates manufacturing, leakage, or end-of-life obligations. Company case studies are useful deployment evidence but are not controlled, portfolio-wide savings audits.
At Carroll Tower in Providence, Gradient reports that 277 All-Weather units were installed across 194 apartments in 12 working days. The company says the completed retrofit is expected to save approximately 450,000 kilowatt-hours annually relative to the building's previous electric-resistance heating. That figure is an engineering projection for a named deployment, not a measured annual result or a claim that each Gradient installation saves the same amount.
Gradient states that a Nexus beta customer reduced energy consumption by 25% through remote set-point optimization and that Nexus was deployed across more than 200 residences in Boston, Detroit, and Washington, D.C. as of February 2026. These are company-reported operational results. NYCHA's $70 million Clean Heat for All challenge selected Gradient and Midea to develop and supply 30,000 cold-climate window heat pumps over seven years; Gradient described its initial award as a $24 million contract. Contracted units and program targets must not be counted as installed units.
Gradient announced an $18 million Series A in 2021. Its earlier materials said its original unit could cut greenhouse-gas emissions by as much as 95%, but that was a scenario-based comparison, not verified fleet impact. The R-290 in the current All-Weather product has a far lower refrigerant global-warming potential than R-32 and R-410A; this refrigerant comparison is separate from electricity-use savings.
Standard-outlet electrification
The All-Weather model runs from 120V power, reducing the need for apartment electrical upgrades that can delay or price out conventional heat-pump retrofits.
Low-disruption installation
The saddle configuration installs room by room without wall penetrations or field-installed refrigerant lines and preserves more window light than a traditional box unit.
Cold-climate heating and cooling
One unit provides year-round space conditioning and uses low-global-warming-potential R-290 in the current cold-climate platform, subject to refrigerant safety requirements.
Fleet-level energy controls
Nexus gives multifamily operators unit telemetry, comfort guardrails, remote set-point management, and power-aware coordination across large distributed installations.
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