Windows Open, Heating On: A New York City Winter 

When New Yorkers hear that familiar clinking sound throughout their houses or apartments, they know winter is here. It means the city’s century-old steam heating system is kicking into gear, insulating around 80 percent of buildings and their residents from the harsh northeastern cold.

Though this system was a boon for the city when it was installed in the 1870s, many city officials and local residents are now concerned with its impact on greenhouse gas emissions. More than two-thirds of citywide emissions come from buildings—much of this from multi-family residential properties. Steam heating is both polluting and often inefficient. 

Beginning this year, things will start to change. A new building law passed in 2019, Local Law 97, is now being enforced, and it may incentivize local property owners to consider switching to a greener heating system, or at least make their systems more efficient. The city’s ability to reduce their building emissions to net zero by 2050, the law’s ultimate goal, depends on these changes. 

Many pre-war buildings are overheated. Residents have no way of controlling the amount of heat their homes receive, leading them to open windows to cool down—and wasting a lot of energy in the process.

“The steam systems are a huge roadblock to major energy improvements,” said Tristan Schwartzman, who analyzes city buildings’ energy efficiency and advises owners on how to cut down their greenhouse gas emissions. “Lots of these buildings with these steam heating systems are using three times as much heat as they need.”

An Ambitious New Law

In steam heating systems, a boiler heats water using natural gas or oil, the water evaporates into steam and is then distributed across a building through radiators. The boiler should be the exact size to meet the heating needs of the property—there are no temperature controls. 

Steam heating systems became widespread in the early 20th century, in the midst of the Spanish Flu pandemic. Medical advice at the time called for people to open their windows so that fresh air could circulate through the home. So, when boilers were installed in these buildings, they were designed with a larger capacity for heating in mind.

John Mandyck, the chief executive officer of Urban Green Council, a nonprofit that collects data on city buildings and advocates for building decarbonization, said that these boilers often leave city apartments overheated. In the past, when boilers were defective, they were often replaced with a boiler of the same size, even if it overestimated the building’s heating needs.

“When [these boilers] break, we’ve always recommended doing the actual audit for the building to understand what the actual [electrical] load is, so that you right-size the boiler,” said Mandyck. “There’s a bigger incentive to do that because Local Law 97 is now making you account for all of your carbon emissions.”

Local Law 97 requires most buildings above 25,000 square feet to adhere to escalating limits to their greenhouse gas emissions, slowly forcing them to rethink their heating and cooling systems, and ultimately to fully electrify their properties.

The goal is for all buildings to be fully electrified, and for the electricity grid to be powered by renewable energy, so that the city can reach its climate targets and improve air quality for millions of residents.

This May, property owners, with the help of design professionals, will have to report their building’s 2024 emissions relative to their square footage and occupancy, and face fines if they do not meet the city’s limits. 

Currently, the limits are high—the Urban Green Council estimates that only 8 percent of buildings are out of compliance. The more stringent limits will come in 2030 and 2035, with the ultimate goal of reaching net zero emissions by 2050. 

“Most buildings are going to be able to get in line with the 2030 requirements for Local Law 97 without electrifying their buildings,” said Schwartzman, the principal and director of energy services at Goldman Copeland. He helps property owners comply with the law and report their emissions to the city government. 

“For 2035, all of the buildings will have to electrify themselves, so that means the heat is going from gas or Con-Ed district steam or fuel oil over to electric,” he said.

“The law is having its intended effect—it has sent the market signal.”

— John Mandyck, Urban Green Council

Schwartzman and his company are currently authorized to do evaluations for 90 buildings. He believes that all of them will be able to meet the 2024 emissions limit, but may struggle later on, especially if their heating systems are inefficient. 

The new law does offer some reprieve to property owners struggling to decarbonize. In December 2023, the city’s Department of Buildings finalized the “good faith provision,” which helps owners avoid penalties if they show that they are making efforts to reduce their greenhouse gas emissions, like installing cleaner technology. 

If a building is over the emissions limit, the owner can, in some cases, buy Renewable Energy Credits, which represent electricity generated by a renewable source, to mitigate fines—though this allowance has been controversial. 

Over time, property owners are slowly moving towards more efficient heating systems—or at least they are thinking about it. According to Mandyck, who was part of the original discussions to help draft Local Law 97, the latest data suggests that the number of buildings that are above last year’s emissions limit has decreased since 2019. 

“The law is having its intended effect—it has sent the market signal,” said Mandyck. “The market hears it loud and clear. So buildings are starting to take steps to lower their carbon emissions, to improve their energy efficiency, and in some cases, to improve just their own data.” 

The Key to Electrification: Heat Pumps

Over the course of the past decade, an appliance that has long been used in milder climates in the South to heat and cool homes has made its way to the Northeast, particularly as technological advances have enabled it to operate efficiently in colder climates. 

The air-source heat pump, which works by pulling heat from outside using a refrigerant and releasing it inside (or vice versa), has been slowly making its way into residential buildings across the five boroughs. It is expected to be widely adopted in the efforts to comply with Local Law 97. 

“We hear from our customers a lot of uncertainty about Local Law 97, but everyone thinks this is a matter of when, not if,” said Vince Romanin, the founder of Gradient, a company that sells easy-to-install heat pumps. “They expect that at some point they’re going to have to switch from a boiler to a heat pump.”

Romanin’s company, along with Chinese company Midea, was chosen to install heat pumps in 30,000 units across New York City Housing Authority buildings as part of the 2022 Clean Heat For All challenge. 

Gradient boasts an hour-long installation time—these air-source heat pumps are delivered prepackaged, and they can be plugged into a normal outlet, like window air-conditioners. Other heat pumps, like the mini-split (which works more like a central air conditioning system), often have to be wired into the home’s electricity system, which requires the help of a professional. 

“Usually when we talk to these customers, the cost of getting in an electrician to put in a heat pump, the cost of asbestos mitigation, the difficulty of displacing a resident to put in a heat pump, the scaffolding cost, the hole in the wall, all of this sort of work that it takes to electrify these older buildings, we found to be really prohibitive,” said Romanin.

For very large buildings, the upgrades and installations needed to electrify their heating systems can be very complicated, particularly if owners want a more centralized heating system (rather than individual heat pump units). Design professionals have come up with creative ways to incorporate new technologies to electrify these buildings in the city, but there is currently no agreed-upon approach.

“[Owners are] starting to look at the more complicated, capital intensive projects that are going to be required to meet 2030 and 2035,” said Schwartzman. “But people are hesitant to jump on those because the projects are complex, the technologies are relatively new and the utility savings are limited.”

Another issue is, of course, cost. Though the city offers incentives for heat pump installation through Local Law 97, like the beneficial electrification credit, the cost is often viewed as too high. 

Unlike increasing efficiency in a building’s heating system, which Schwartzman says pays for itself after two or three years, full electrification of a large building can carry a large cost which will not be quickly recuperated by savings in utility bills, particularly as companies like Con Edison continue to hike their electricity rates. 

Air-source heat pumps often serve one apartment each. This moves the heating system away from a centralized boiler and into individual homes, allowing residents to control the heating and cooling which cuts back on energy waste. 

In the dead of winter, air-source heat pumps can end up using up large amounts of electricity to pull in the small amount of warm air that remains outside—this can increase a building’s electricity bill, and even force property owners to upgrade their electrical capacity to accommodate the higher load.

Clean energy advocates argue that property owners will suffer either way, as escalating climate disasters hike insurance premiums for their buildings, and the risk of flooding increases across the city.

Romanin also said that the cost of installing air-source heat pumps is not always higher than the cost of replacing and consistently maintaining a boiler, which often have reliability issues in the city. In his work with the city’s housing authority, he believes that the numbers support the transition to heat pumps. 

“The energy that it took to heat the homes that had Gradient [heat pumps], versus the homes that had steam, was 85 percent less,” said Romanin. “You’re shifting that energy cost from either natural gas or oil […] to electrons, which are generally more expensive on a per energy basis, but this still translates to about a 50 percent reduction in heating bills.”

Air-source heat pumps are still evolving, particularly in terms of their efficiency in sub-freezing temperatures and the refrigerant they use. Refrigerants are historically known to contribute to the depletion of the ozone layer. Today, the refrigerants used in heat pumps don’t impact the ozone layer, but still contribute to global warming. 

In the past, technology like air-source heat pumps was not widely available for buildings with a large amount of units. Alloy, an architect-led development firm based in Brooklyn, built the city’s first all-electric skyscraper last year. When they began designing the residential property in 2019, air-source heat pumps were not available on the scale that they are now. 

“With the manufacturing availability of it at this scale […] we couldn’t really buy 500 individual heat pumps for apartments,” said AJ Pires, the founder of Alloy.

Instead Pires installed water-source heat pumps—which pull heat and cold from water instead of air—in each apartment. Water from an energy efficient electric boiler runs through each pump, helping to heat these rooms.

The availability issue has since been solved—Pires plans to use individual air-source heat pumps for his next building at One Third Avenue. This will enable him to make use of an electric boiler only on the absolute coldest days of the year. 

For New Buildings, an Easier Task

The future of New York City’s buildings is likely to look a little different. Bolstered by legislation like Local Law 97 and Local Law 154 which phases out the usage of fossil fuels in new buildings, the tide is turning—just very slowly. 

In 2019, when he broke ground on his company’s all-electric skyscraper, Pires was ahead of the curve. But now, he says the city’s real estate industry is catching up, with more and more electric heating systems being installed in new buildings.

“One of the things that’s funny is, when we were engineering—pre-construction—the all-electric building with our mechanical engineers, we were the only people doing it,” said Pires. “Now, if you ask them, all of their multi-family clients that are making buildings and designing buildings now, they’re all electric.”

The cost of making these changes in the design phase, Pires says, has amounted to around a 2 percent premium—slight increases in pricing can be traced to the induction stoves and the electric resistance boiler. 

“You’re also talking about an entire building—it cost $300 million to make,” said Pires. “So whether the 440 cook tops were $100 more or not, that’s pretty marginal relative to the total cost of the project.”

The people looking to rent or buy new homes, particularly those of means, are also increasingly considering homes for their sustainability. When Alloy surveyed the residents of its all-electric skyscraper, 57 percent said that “they considered sustainability as part of their choice”

In the last couple of years, interest has also gone up in passive houses, which are homes that are very well insulated, thus requiring up to 90 percent less energy to heat and cool them. 

As property owners work to comply with Local Law 97 emission limits for 2024, and weigh their options for future decarbonization, clean energy advocates are optimistic. The transition could be costly, they say, but worth every penny. 

“We’re not creating a law to create a nuisance for people—we’re doing this to solve the climate impacts that we’re seeing faster and more prevalent in New York City,” said Mandyck. “We’re literally talking about the continuing operation of the city as we know it.”