It was the midst of a July heatwave, with humidity sticky in the air. Phoebe Saldana sat in the colorful plaza of her East Harlem housing complex, watching her two young daughters ride scooters and climb on workout equipment.

They were getting some playtime outside before returning to the cool respite of their two-bedroom apartment. To Saldana, 37, the air conditioning was a godsend.

“We were living with no air conditioner for a long time,” said Saldana, who moved in from a Brooklyn shelter. “It’s amazing. I, like, never turn it off.”

In the winter, she said, her apartment stays warm, without cold drafts. Inside, she can barely hear the trains chugging along the elevated tracks running next to the building.

Phoebe Saldana lives at the Sendero Verde affordable housing development in Harlem. 

“It’s very comfortable to live here. It’s peaceful,” she said.

Saldana lives in Sendero Verde, a 709-unit complex that houses low-income and formerly homeless individuals. Completed in April, it’s the largest certified passive-house building in the United States, and its champions say it can serve as a model as other cities and states seek to tackle both the housing crisis and the climate crisis.

“Ideally, this is the way that all affordable housing should be developed,” said Sadie McKeown, president of the Community Preservation Corporation, an affordable housing finance company that was not involved with Sendero Verde.

“When you develop something [with] passive house [principles], the benefits to the tenants are great,” she said, noting sound insulation, fresh air and lower bills. “The buildings just stand up better to extreme weather conditions, whether that’s wind, rain, heat or excess cold.”

Developers say Sendero Verde uses about half the energy of a comparable non-passive building thanks to insulation, sealing to prevent leakage, thick windows and ventilation.

The result: clean air, quiet interiors and stable temperatures – even if the power goes out. Spurred by both government incentives and mandates to build greener, such projects offer comfortable, healthy environments to residents often most vulnerable to the effects of a warming planet.

Sendero Verde consists of two mid-rise buildings, completed in 2022, and a 34-story tower, completed in April. Other than the gas water heater, the buildings are powered by electricity, including the stoves in the kitchens. Gas stoves emit methane, a potent greenhouse gas, and have been shown to produce indoor air pollution, contributing to childhood respiratory problems. (Last year, New York became the first state in the nation to ban gas stoves in new buildings, following New York City in 2021.)

There are also community gardens, shared outdoor terraces with native plants, a fitness center, a playground, computer labs and multi-purpose rooms. One of the buildings houses a charter school, with additional space reserved for retail and social services, such as occupational therapy and mental health care.

“For our residents, we have a responsibility to give as much resilience as possible,” he said. “So I think passive housing is a really good methodology and opportunity for that.”

Sendero Verde, which means “green path” in Spanish, takes up an entire city block in East Harlem, a low-income, formerly redlined neighborhood whose dearth of trees makes it significantly hotter  than, say, the wealthier, leafier Upper East Side neighborhood a few blocks south.

As cities scramble to tackle housing and climate crises, complexes like Sendero Verde answer their calls.

Those disparities put residents at a higher risk for heat-related illnesses and death. Black and Hispanic New Yorkers are more likely to die from heat stress compared to white people, according to city statistics.

In 2016, as part of a broader neighborhood rezoning plan, the housing authorities called on developers to submit plans for sustainable, affordable housing on a city-owned lot, offering subsidies for the project.

The competition was “a good impetus, kind of getting us and getting others in the industry to maybe speed along this change”, said Jessica Yoon, managing director at L+M Development Partners, one of Sendero Verde’s developers. “We were probably all plodding along towards it anyways.”

Construction costs were about 6% to 8% more than a non-passive house project, according to the developers, though costs have come down since then.

“We’re trying to do dense and smart and land-sensitive buildings, so passive house is a good fit for that naturally,” said Jennifer Bloom Leone, chief sustainability officer for New York City’s department of housing preservation and development. “As the city moves off of fossil fuels toward all-electric new buildings, passive house can help significantly reduce energy use. This will minimize the risk of grid outages and rising utility costs while providing other benefits like occupant health and safety.”

There are currently over 1,860 certified passive houses in New York, but that figure is soon expected to grow. Last year, state and city officials launched a $15m fund to “fast-track the creation of 3,000 energy-efficient and all-electric affordable homes in New York City”. The program would support up to 30 buildings – in effect doubling the number of passive projects the city has financed since 2014.

The Sendero Verde affordable housing development in Harlem uses energy efficient “passive house” heating and cooling designs.

Because they are so well-insulated, passive homes use less energy than traditional homes, which means lower utility bills. This efficiency is especially helpful to consumers who are electrifying their homes, since electricity – even though less emissions intensive – often costs more than gas.