How a Rhode Island apartment building for seniors installed 277 heat pumps in just 12 days

Carroll Tower, a 194-apartment public housing development in Providence, Rhode Island, was built in 1974. For more than 50 years, residents there relied on electric baseboards for heating and their own window air conditioners, if they had them, in the summers. But now, the entire building has been retrofitted with a modern HVAC system: 277 heat pumps from Gradient, a San Francisco-based climate tech startup, will heat and cool the property. [Photo: courtesy Rhode Island Office of Energy Re...