"A few years ago, around 10,000 buildings in New York City were burning the cheapest, heaviest and dirtiest forms of heating oil, known as No. 6 and No. 4.," writes Kia Gregory. "That small percentage of real estate contributed more soot pollution than all the cars and trucks on the streets, the city found, and was a prime contributor to thousands of premature deaths, hospital admissions for lung and respiratory illness, and emergency room visits for asthma each year."
Under a 2011 city law [administered under NYC Clean Heat], No. 6 will be banned as of July 1, 2015. By 2030, all buildings in the city must use cleaner fuels such as No. 2 oil or natural gas.
High conversion costs and inadequate natural gas infrastructure are the primary culprits for the slow progress in meeting the law's targets.
To date, half the buildings no longer burn No. 6, but "hundreds have switched to No. 4, which though permitted for another 16 years, can be only slightly less noxious, depending on the supplier. Converting a boiler to a lighter oil can cost between $5,000 and $17,000...Switching to natural gas can cost hundreds of thousands of dollars."
Michael J. Wolfe, president of Midboro Management Inc., which manages about 100 co-ops and condos in Manhattan, said that most of his clients are switching to No. 4. “And some are burning No. 6 for as long as they can,” Mr. Wolfe said. “I think it’s aggressive,” he said of the city’s mandate. “I don’t think they gave us enough time, considering how many buildings there are.”
Another limiting factor is natural gas infrastructure - some parts of the city lack pipelines. "Between 2011 and 2013, Consolidated Edison has switched 1,535 large buildings to natural gas from dirty heating fuels. But its plan to expand its natural gas network is not scheduled to be completed until 2019."
Gregory cites a building in Washington Heights whose "board voted to convert to natural gas. But without straight access to a gas main, the owners were 'forced' to switch to No. 4, a matter of cleaning the boiler and changing the oil."
Yet even at this slow pace, significant air quality improvements have been attained.