Rhode Island Senior Housing Completes Massive Heat Pump Retrofit in Record Time

Carroll Tower, a 194-apartment public housing development in Providence, Rhode Island, was built in 1974. For more than 50 years, residents relied on electric baseboards for heating and personal window air conditioners—if they had them—for cooling in summer months.

Now, the entire building has been retrofitted with a modern HVAC system: 277 heat pumps from Gradient, a San Francisco-based climate tech startup, now provide both heating and cooling. The installation, completed in just 12 days without drilling or rewiring, marks one of the largest heat pump retrofits in the United States.

The $1.25 million project was a public-private partnership between the Providence Housing Authority, Gradient, the Rhode Island Office of Energy Resources, energy consulting firm Abode Energy Management, and Envr Air, which accelerates HVAC electrification.

According to preliminary estimates, the upgrade will save Carroll Tower 450,000 kilowatt-hours annually, reducing energy costs by about $94,500 per year. It will also cut greenhouse gas emissions by 219 tons each year—equivalent to removing a gas-powered car from the road for approximately 500,000 miles.

Why Heat Pumps Are a Climate Game-Changer

Residential buildings account for about 20% of the country’s carbon emissions, with heating and cooling responsible for over half of that energy use. Traditional HVAC systems can also leak natural gas or refrigerants, which are potent greenhouse gases.

Electrifying these systems can drastically reduce emissions. Heat pumps are particularly effective: even when powered by fossil-fuel-based grids, they still cut emissions significantly compared to conventional heating systems.

From New York to Rhode Island: A Scalable Solution for Older Buildings

In 2022, the New York City Housing Authority (NYCHA) launched the “Clean Heat for All” challenge, inviting manufacturers to develop easy-to-install electric heating and cooling systems. Gradient was one of the winners (alongside China’s Midea) and will supply 10,000 of its window heat pumps to NYCHA buildings.

Some NYCHA developments have already received the upgrades. In 2023, a Queens public housing complex installed 72 heat pumps, resulting in an 87% reduction in energy use and a 50% cut in energy costs.

Since then, Gradient has expanded partnerships with housing authorities in Boston, Chelsea and Lynn, Massachusetts, and beyond. The company’s heat pumps are especially well-suited for older, vintage buildings—including many public housing properties—says Vince Romanin, founder and CTO of Gradient.

‘You can get your window back.’

Carroll Tower is one of two elderly-only buildings in the Providence Housing Authority. The average age of residents there