Oil Backups: Keeping Skyscrapers in Extreme Cold

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For large buildings, winter isn’t just about comfort – it’s a matter of safety and legal requirement to maintain heat. During normal conditions, a high-rise’s primary heating source might be natural gas or district steam. However, in periods of extreme cold, those primary sources can be strained or interrupted, and that’s where heating oil steps in.

Many high-rise buildings in NYC are equipped with dual-fuel boiler systems. In these setups, the boiler can burn natural gas under most conditions, but it also has the capability to burn No.2 heating oil as needed. Why go through the expense of maintaining two fuels? Because gas utilities in New York operate “interruptible” service contracts for large users. On the coldest days when demand for natural gas spikes, the utility (like Con Edison or National Grid) may temporarily cut off gas supply to big commercial customers.

Residential customers and critical services get priority on the gas system, while certain high-rises agree to switch to oil heat in exchange for lower gas rates the rest of the year.

It’s a practical way to reduce strain on the gas network during a polar vortex. In fact, on an interruptible system, gas is used about 95% of the time, but “on very cold days when gas demand is high, the utility will shut off the gas and require the high-rise building to use No.2 oil until peak usage subsides.” This arrangement ensures the building can keep the heat on no matter what’s happening with regional gas supply.

Even buildings with firm (non-interruptible) gas service might keep an oil backup. Natural gas systems in NYC can face pressure drops during extreme cold snaps if infrastructure is over stressed. By having an on-site oil supply, a high-rise can fire up its oil burners if gas pressure falls too low to meet the building’s heating load. Oil becomes an insurance policy – a readily available fuel stored right in the building’s basement tank, waiting to kick in if needed.

One key reason high-rises still rely on oil in winter is the security of having fuel on-site. Oil can be stored in large tanks (some buildings have tens of thousands of gallons in basement tanks or vaults). This means that even if roads are closed, gas lines are constrained, or power is out (for those on steam or electric heat), the building has a self-contained reserve of energy ready to go.

During a severe blizzard or emergency, a building management team can increase oil deliveries ahead of time and effectively be self-sufficient for days or weeks. Gas supply, by contrast, is dependent on the external pipeline network and utility capacity.

For example, many NYC hospitals, schools, and high-rise residential towers maintain oil reserves explicitly for emergencies. If the gas grid ever struggles or a polar vortex causes record demand, these facilities seamlessly switch to oil and keep critical heat and hot water running. It’s a resilience strategy. In some cases, city regulations or insurance requirements for essential buildings mandate a backup fuel source on premises.

It’s worth noting that Con Edison’s steam network (which supplies steam heat to many Manhattan high-rises) similarly doesn’t rely on each building’s boilers – but even Con Ed steam buildings often have a backup boiler that can run on oil. Why? Steam service is very reliable, but if there were ever a rare steam outage or needed maintenance, an oil-fired boiler can serve as a fallback to heat the building.

Engineers design multiple redundancies for high-occupancy buildings; an oil system is a common solution.

In extreme cold, a high-rise heating system faces maximum stress. The outdoor temperature might be in the single digits (°F), wind whipping between skyscrapers, and every apartment thermostat cranked up. This is precisely when oil fuel shines as a dependable heat source:

• High BTU Output: Oil burners generate a lot of heat per gallon – No.2 heating oil packs about 139,000 BTUs per gallon, delivering intense heat…