A New Fix for the Ancient Problem of Imbalanced Heat

Imbalanced heat is a perennial problem in many buildings with old-fashioned, cast-iron steam radiators. But one Brooklyn co-op has found an innovative solution. The Radiator Cozy, from the Brooklyn-based Radiator Labs, is a "smart radiator cover" that uses insulation, a small fan, and computer-regulated temperature controls to keep too much steam out of hot apartments and to send more steam to cold ones.

It's not inexpensive, even with government incentives, since each Cozy has to be custom-manufactured and installed. And the payback in terms of lower energy bills can take five to seven years. But for Clinton Hill, a 12-building complex of 1,200 apartments near the Brooklyn Navy Yard, there has been an immediate payoff.

"Our complex had been experiencing incredible overheating and underheating for decades," says Timo Lipping, a financial planner and former president of the co-op board. "Some people were kind of pooh-poohing [the payback time] as not fast enough, but payback is not the only payoff. It's also people being comfortable in their apartments – and that we can advertise we have this new technology that other co-ops don't."

George Switzer, an architect and board member, adds: "The overheating was for many years the No. 1 issue people had. Less so people who were underheated. Some people were extremely overheated – like 90-plus degrees in their apartments. Resident comfort is a real issue."

How does a Radiator Cozy work? Each of these insulated sheet-metal covers contains a thermostat, accessible via both a mobile app and a controller on the Cozy itself, so that each resident can set a desired temperature for that apartment. If the apartment is too cold, a built-in fan turns on and pushes heat into the room. If an apartment is at the set temperature, the fan turns off, and steam that otherwise would have overheated the room gets directed to colder apartments in that steam-pipe line.

"Rather than have a heating system with a single control that controls the heat for the whole building, it allows every radiator to have its own control," explains David Sachs, director of audits, design and implementation for Bright Power, the energy consultant on the Clinton Hill project. "So every apartment and every room is able to control its own heat."

"It's very hard to balance a steam building," says Marshall Cox, the chief executive of Radiator Labs. "The reason is that when these buildings were built almost a century ago, or even more in some cases, they were pretty well-balanced. But then we invented – and more or less universally retrofit – double-pane insulating glass, which changed how much heat those rooms needed. But you still had the same huge radiators." And so, because steam heat is a closed system, too much heat in some apartments often means too little heat in others.

The board devised a pilot program to test the Radiator Cozy. "We picked some overheated apartments and underheated apartments to see how it would fare," says the co-op’s property manager, Steve Greenbaum of Charles H. Greenthal. "We wanted to see if people liked it and for us to see how it worked, just to see if this was something that was feasible. And the response was overwhelmingly positive."

Cozys were installed in 20 units. "A bunch of us decided to just pay for [Cozys] ourselves,” Lipping says,  “with the caveat that if it's not introduced complex-wide we would not be reimbursed, and if it was introduced, we would be."

The pilot project ran during the winter of 2018. "It was amazing," Lipping says. "It was the best winter we'd ever had. The thing worked as advertised – it really did."