New York City has pledged to reduce greenhouse gas emissions by 40% by 2030 and by over 80% by 2050, as part of its Green New Deal plan for a more sustainable future. The New York City Housing Authority—the largest provider of public housing in North America—is fulfilling this pledge by retrofitting its huge portfolio of housing units, which is no easy task. Its approach can serve as a blueprint for other cities.
Achieving these goals will not be simple for The New York City Housing Authority (NYCHA). Its residential footprint covers over 500,000 tenants in some 335 housing developments, and buildings are the largest source of greenhouse emissions. Under Local Law 97, all buildings that exceed 25,000 square feet must meet new energy efficiency and emissions standards. The city also has banned the use of natural gas for heating and cooling in new buildings.
As a result, NYCHA is pushing hard on several fronts to decarbonize its buildings and convert to beneficial electrification where possible, says Gianluca Galletto, former managing director for technology and innovation partnerships at NYCHA.
“The New York City government plans to decarbonize before the end of the decade—that includes all the buildings that belong to the government, which, if you include NYCHA public housing, goes up to 600 million square feet,” says Galletto. “The only difference is that for public housing the reductions apply to the portfolio on average, not for each single building, so it’s a little more flexible.”
Following a sustainability roadmap
NYCHA is following a Sustainability Agenda that it published in October 2021 that sets out a decarbonization and a climate mitigation roadmap comprising a variety of solutions. These include rooftop solar panels, which NYCHA is installing on public housing facilities to achieve 30MW of power production. On others, it is putting in small wind turbines for additional power, and green roofs to reduce heating and cooling needs. The agency is also assessing feasibility of installing solar plus storage on two of its buildings.
Another measure is transitioning from fossil fuels to clean, electric powered systems for heat, hot water, and cooking in housing units. Improvements include electric induction stoves and ovens and highefficiency heat pumps to provide space heat and hot water. Domestic water and space heating—and cooling—account for 85% of energy needs for New York public housing, explains Galletto. However, while this will reduce emissions from buildings, the full decarbonization effect will depend on New York State converting to carbon-free energy sources for its electricity generation.
Heating and cooling adjustments
NYCHA is also digitizing building heating and cooling systems to better manage distribution. “There are huge quality of life problems because of how old buildings were built,” says Galletto. “One apartment is super-hot in the winter, so they open windows or turn on the air conditioner, while another part of the building is too cold. By changing the architecture of the heat production and distribution, you start to affect the way it is distributed by units.”
This includes installing smart meters and sensors in each apartment. As part of this effort, up to 30,000 families will receive broadband service at a greatly reduced rate, which permits remote management of heating and cooling. “That means no one can put the heat up too high or the air conditioning too low,” he says.
NYCHA is looking to Scandinavia for ideas for district heating and thermal networks to ensure that heating and cooling can be shared among buildings and that energy is not wasted. Copenhagen and Stockholm have thousands of miles of heat networks, piping that connects underground, Galletto points out. “Buildings can become prosumers of energy because the heat that they don’t use can be used by the building beside you. It’s a little bit like the cloud, or like network storage for different computers, where you can share some of the free hard drive.”
Getting these heat networks and geothermal heating and cooling units built won’t be easy in New York, with its high population density and streets with a huge underground network of pre-existing piping and wiring. But Galletto says NYCHA will draw on new technologies to build on existing piping—and much older district heating using steam that dates from more than 100 years ago.
These technologies include heat exchangers, geothermal capabilities, and heat pumps, which offer a potential for a more than three-fold increase in efficiency and reduction in energy, Galletto says. “With heat pumps, and with the difference in temperature between inside, outside, underground, and above ground, you can also provide cooling,” says Galletto.
In partnership with the New York Power Authority and the New York State Energy Research and Development Authority, NYCHA issued a request for proposal seeking a heat pump that can be installed through a window. The three agencies are currently evaluating six proposals and hope to award a contract in 2022.
He adds that NYCHA is looking to replace all gas boilers over 15 years old—those that are the least energy efficient—with heat pump technology. In other NYCHA developments—10 at present—the plan is to move to geothermal heating and cooling that will replace use of natural gas completely, with a single plant serving up to 10 buildings.