Manhattan Co-Op Restores 1950S Steam Heating System, Reduces Gas Usage by 15%

At Cabrini Terrace, a 217-unit co-op in Manhattan’s Hudson Heights, the board proved that sometimes the best solution isn’t the newest one. It recently restored the building’s original 1950’s steam heating system, bringing it up to its maximum efficiency and shaving 15% off of the building’s gas usage. 

The building's vacuum-return steam heating system, a technology developed in the 1930s, was designed to provide steady heat throughout the winter months. “It’s old technology, but it’s efficient,” says Kenneth Stropoli, sales application engineer at the HVAC contractor GS Dunham. However, over the decades, deteriorating parts and quick fixes had compromised its effectiveness. The boiler's constant cycling on and off meant inconsistent heating, leading to excessive fuel use, noisy radiators, and overheated apartments. As board member Anastasia O'Malley notes, "We'd drifted away from the design basis for the system."

Faced with both these issues and the need to comply with Local Law 97's emissions requirements, the board embarked on a $320,300 restoration project. According to William Zoha, founder and CEO of Prescient Energy and the building's energy consultant, the original design contained numerous energy-saving features that needed to be restored one by one.The two-year project involved replacing and reinstalling many components, including steam traps, adjustable radiator valves, a new vacuum pump, and new Vari-Vac heating controls. Individual apartments required radiator valve and trap replacements. “Constant communication and updates to this project were critical to its success,” says O’Malley. 

One of the project's main challenges was creating an entirely closed pipe distribution loop, essential for the vacuum system's proper functioning. “If you are not able to create and maintain a vacuum in the system, it’s not going to work properly,” says Stropoli. “We knew if we could get the tightness up to par the building would really be seeing benefits.” Additionally, he says, maintaining system tightness is key to realizing its benefits. The system now undergoes annual leak checks as part of ongoing maintenance. 

The co-op used its reserve funds to cover the cost of replacing the vacuum system components. Under the bylaws, replacing the system parts within the apartments — the radiator steam traps and valves — was the responsibility of shareholders. The co-op helped shareholders pay for the work by offering a credit of $200 per radiator, thereby meeting 42% of the cost. 

Based on data from 2023, Cabrini Terrace’s annual Local Law 97 penalty exposure beginning in 2030 was $24,000. A 15% reduction in natural gas use puts the building on track to put a dent in this. To further lower their potential penalties, the co-op recently installed a combined heat and power plant to help generate electricity and take care of the domestic hot water. “This means we’ll be able to switch off the boiler in the summer,” O’Malley says. In addition, the co-op, which was an early adopter of solar back in 2007, is exploring replacing and upgrading its rooftop panels with more efficient models.