Keeping the Big Apple Warm

If you were asked, what does New York City mean to you, the answer will be different for all of us. If you know it well, the "city that never sleeps" will hold a memory-full of highlights to choose from. It's vibrant mix of cultures, and relentless energy make for an unforgettable experience. But, even to those who've never set foot on Manhattan, its skyline is instantly familiar. Dominated by high-rise buildings reaching for the clouds, it symbolises ambition, optimism, and determination; the American Dream in concrete, steel, and stone.

From ground to sky: the origins of the skyscraper

The familiar New York skyline we think of today wasn't always that way. It took a combination of factors to be able to build ever upwards. The first high-rise building in America wasn't even in the city; Chicago got there first, with the 12-storey Home Insurance building in 1884. But it was the technological advances of the late 19th century that made dreams of building higher a reality.

Bessemer steel forged into longer sections enabled taller, more flexible frames than the old cast iron allowed. Sprinkler heads to deal with any fire risks meant the old 23-metre-high limit on construction was relaxed. And, AC electricity was patented, leading to elevators that could carry people up to new heights.

As for how to keep people comfortable in these new towering edifices during the biting cold of winter, the answer was found with steam.

Sarco’s New York Story

By the time the distinctive tower on the Singer building was nearly completed, rising 40 floors above the city's streets, New York was a beacon for American progress. As Lewis Sanders sailed into to the harbour in 1907, after almost a week's crossing from the UK, the Beaux-Arts style tower of red brick and bluestone would soon become the tallest building in the world, if only for a year.

He wouldn't have been alone in witnessing the evolution of the city's skyline. Ellis Island, where America's immigrants were processed, saw its busiest ever year in 1907, dealing with 1.25 million hopeful arrivals.

However, unlike most of them, Sanders' journey had a definite goal; to set up the American branch of his British employer's company. The same year the Sarco Fuel Saving and Engineering Company set up shop in Lower Manhattan. Within a few short years, in 1915, it simply became Sarco Co. Inc. It's letterhead listed its core offerings, including CO₂ recorders, steam meters, fuel and gas calorimeters, draft gauges, steam traps and thermostatic regulators.

Steam traps were a mainstay of the business's growth, and as the city experienced rapid growth, the demand for quality traps helped establish Sarco's reputation. Ruth Greenfield, Vice President during those heady years, would later recall,

Why New York City Embraced Steam

The answer lies in steams unique properties as an energy transfer medium. It carries far more heat than water, and has the bonus of not requiring circulating pumps to get it to where it's needed. That saves not only on the cost of the circulating pumps, but the complications that arise from controlling the pumps and their flow to manage the heat transfer.

When it came to getting steam to radiators throughout a high-rise building, steam's advantages were clear. By introducing a vacuum, instead of steam pushing air out of the system, it is drawn by the vacuum at speeds of up to 150 mph throughout the heating system. This ensures there is rapid and even heating throughout the building.

A good example of this is the heating system in the Empire State Building. When completed in 1931, with its 102 floors, it became the world's tallest building. Today, after a major energy efficiency project, and 92 years since it was completed, it still relies upon steam to keep those who work in it warm. All with 1.5 psi steam pressure - and 6,600 steam traps. The detailed efficiency retrofit reduced energy use by more than 40%, and carbon emissions by 54%.

Steam Beyond the Skyscraper

Using steam to heat buildings was not a new discovery. Joseph Nason, who played a role in developing the cast iron radiator, had done so in President Pierce's White House in 1855. By 1882 the New York Steam Company (the forerunner of Con Edison) was providing the benefits of steam to nearly 1,600 customers from Battery Park to 96th Street.

And, whilst the majority of the new high-rise buildings were built to maximise space and profit for business use, steam would find its way into New York's residential homes too.

You may think that things have moved on. That away from its clear advantages when it comes to the city's tallest structures, it's been replaced. You would be mistaken.

As Urban Green note, the impact from using steam was revolutionary, "It replaced fireplaces and stoves, offering better indoor air quality, comfort and efficiency." When much of today's New York was built, in the early decades of the twentieth century, there were health concerns about being inside without ventilation. The thousands of immigrants arriving in the city led to overcrowded tenements, to fear of disease and "vitiated air" (effectively breathing in the air of others). The fear of diseases like tuberculosis, and devastating pandemics like the Spanish Flu of 1918 added to this belief.

The solution? Keep the windows open, even in the depths of winter. It's advice that hasn't changed in a century. Remember only a few years ago, during the COVID-19 pandemic, the guidance was to keep windows open if sharing a room with others.

This may have been prudent from a public health perspective, but it directly led to the misconceptions surrounding steam today.

Too Hot to Handle? Steam’s Place Today

It can get bitterly cold in New York in winter, especially when a chill north-easterly wind is blowing. To compensate for the open window policy, boilers and radiators were fitted that could heat properties with windows open even on the coldest days. When the fuel that generated the steam shifted from coal to oil and then to natural gas, replacement equipment was oversized, erring on the side of overheating rather under-heating.

More efficient, double-glazed windows replaced the old, and insulation and air sealing improved, all adding to the stifling nature of the original heating systems. Coupled with poor maintenance schedules, these oversized steam systems mean people now open their windows in winter because they're overheated.

When it comes to buildings that have their own heating systems, Urban Green is clear on the way forward, "As steam systems age out, they should be replaced by hydronic systems or by electric-powered heat pumps." Of course, that replaces one energy transfer medium, steam, with another, hot water. The question of how that electricity is generated still remains. If not from natural gas (predominating over oil and coal these days), but from renewable energy sources, then why not generate steam from the same energy source?

Even advocates for removing steam from the equation, accept that such a mammoth undertaking is not enough in the short term. As Urban Green note, "Another reason to invest in steam now is that, before buildings fully electrify, we may see the development of hybrid heating systems that continue to use steam to supplement heat pumps."

They also recommend a range of immediate measures to balance steam systems, look at rectifying oversized boilers, and introduce insulation and temperature control factors that would have payback of eight years or less.

Ultimately, it's clear that it's not a case of "either/or"; that's a false dilemma. Properly installed, well maintained, and with the various upgrades possible, steam systems are certainly viable. As Urban Green concedes, "If steam systems run properly, they get steam to every radiator in the building, and tenants get more consistent heat without being overheated."

Two Areas Where Steam Makes Perfect Sense

However positively you view the potential for heat pumps, they fall short when it comes to high-rise buildings. Imagine the cost in lost real estate value when you consider that every 20^th floor will have to be given over to them to be able to push hot water ever higher. When it gets cold outside, a backup system will almost always be needed to boost their output. And, remember, they still need electricity to operate, 24 hours a day, 365 days a year.

The physics haven’t changed either. One pound of condensed steam carries more heat than 25 pounds of hot water cooled in radiators by 4.4°C, with no pumping needed.

Then there is Con Edison, who now operate the world’s largest steam system. Through more than 100 miles of pipes, steam is centrally generated at six sites before being distributed around the lower half of Manhattan. Some of these sites are just for generating steam, others produce electricity too. And, it’s not just used for heating. It supplies New York’s hospitals (for sterilisation purposes), laundries, and food processing businesses.

Nor is it just the Empire State Building that relies upon steam. Con Edison’s network provides steam for heating, cooling (thanks to absorption refrigerators), and hot water to the United Nations, Grand Central Terminal, and the Chrysler Building. The longest trading stock on the New York Stock Exchange, Con Ed sees the future of steam positively, with a long-range plan focused on “decarbonizing our steam system.” 

Far from seeing steam as obsolete, Con Edison are recognising that steam is still an option. And, they will also be generating much of the electricity used to power any new heat pump installations in the process.

A Tale of Two Cities

Opinions differ on the future for heating New York. Some, like Urban Green, see it as something that will have to change, being replaced by hydronic systems or electric-powered heat pumps. Unsurprisingly, Con Edison view steam as the city's "hottest new clean energy system", with a bright future ahead of it. Whether you consider it the best of options, or the worst of options, there is consensus that the first step is to improve the efficiency of what's already in place. Steam has kept New Yorkers from feeling the cold for over a century, and will continue to do so for the foreseeable future.

As for us? Now, as Spirax Sarco, steam's use in buildings still represents a small, but important part of our business, accounting for around 3% of our Group revenue. We're no longer based in Madison Avenue, and we work throughout the United States. We've continued to learn, and share, our steam expertise since that first office opened in 1907. Steam is still our business, and we continue to explore the many avenues it offers for the future.

Sources:

• Patrick Sisson: The curious history of steam heat and pandemics
• Christina Nunez: How Hidden Labyrinths Under Cities Are Becoming Clean Energy Powerhouses
• John Pinching: Empire state building future inside out
• Igor Zhadonovsky: https://www.intechopen.com/online-first/84666
• Con Edison: Steam system as NYCs new clean energy solution
• Urban Green Council: Demystifying steam
• Nigel Watson: Knowledge, Service, Products, 2019.