For fifty years, the residents of Carroll Tower, a public housing complex in Providence, Rhode Island, navigated the seasons with the blunt instruments of 1970s infrastructure: electric baseboard heaters and the occasional, self-installed window air conditioner. The 194-apartment building, completed in 1974, represents a common friction point in the American housing stock — structures built for a different climate era that are now inefficient, expensive to maintain, and increasingly uncomfortable.

A recent $1.25 million public-private initiative has transformed the tower into a test case for rapid decarbonization. Over just 12 days, workers installed 277 heat pumps from Gradient, a San Francisco-based climate tech startup. The project was notable not just for its scale, but for its lack of friction; the units were installed without the invasive drilling or extensive rewiring typically required for HVAC overhauls. The speed of the deployment suggests that the primary hurdle to retrofitting older buildings may be shifting from engineering complexity to logistical coordination.

The economics of non-invasive retrofits

The environmental and economic dividends are significant. Preliminary estimates suggest the upgrade will save 450,000 kilowatt-hours annually, cutting nearly $95,000 from the building's energy bills and reducing greenhouse gas emissions by 219 tons — an impact equivalent to removing half a million miles of gasoline-powered driving.

Those figures matter most in the context of who bears the cost of inefficiency. Public housing residents, overwhelmingly low-income and often elderly, are disproportionately exposed to energy burden — the share of household income consumed by utility bills. Baseboard electric heating, a technology widely deployed in mid-century multifamily construction because of its low installation cost, is among the least efficient methods of climate control still in widespread use. It converts electricity to heat at a one-to-one ratio. Modern heat pumps, by contrast, move existing heat rather than generating it, routinely delivering two to three units of heating or cooling energy for every unit of electricity consumed. The gap between the two technologies represents decades of compounding waste embedded in the nation's housing infrastructure.

The Carroll Tower project's design around non-invasive installation is a deliberate strategic choice. Traditional HVAC retrofits in occupied buildings require temporary relocations, extended construction timelines, and significant structural modification — costs that often render upgrades politically and financially impractical for housing authorities operating under tight budgets. By using units that mount in existing window openings without ductwork or exterior compressors, the Providence deployment sidestepped the most common sources of delay and expense. Twelve days for 277 units translates to a pace that, if replicable, could reshape the calculus for municipal decision-makers weighing climate commitments against operational disruption.

A scalable model, or an isolated case?

As residential buildings account for roughly 20 percent of U.S. carbon emissions, the Providence project invites a broader question about whether rapid, non-invasive retrofits can move from demonstration to standard practice. The American public housing portfolio contains hundreds of thousands of units built in the same postwar era as Carroll Tower, many with identical heating systems and similar structural constraints. The federal government has signaled interest in building electrification through various incentive programs, but funding mechanisms remain fragmented across agencies and jurisdictions.

The deeper challenge is institutional, not technological. Housing authorities operate under layers of procurement regulation, deferred maintenance backlogs, and competing capital priorities. A twelve-day installation timeline is striking, but the months or years of planning, financing, and approval that precede it remain the binding constraint for most public agencies. Whether the Carroll Tower model can compress those upstream processes as effectively as it compressed the physical work is an open question.

There is also the matter of performance over time. Heat pump technology is well established, but deploying hundreds of units in a building with aging electrical infrastructure introduces variables that only sustained monitoring will resolve. Energy savings projections are based on models; actual performance will depend on resident behavior, grid conditions, and maintenance capacity that public housing agencies are not always resourced to provide.

Providence has produced a proof of concept. The tension now sits between the clarity of the engineering solution and the complexity of the institutional systems that must adopt it at scale. Whether other cities treat Carroll Tower as a blueprint or an anomaly will say less about the technology than about the political will to prioritize building stock that serves populations with the least market leverage and the greatest climate exposure.

With reporting from Fast Company.

Source · Fast Company