Carver House: A Perspective on Passive House Workforce Development (WED 12/7)
November 3, 2022

NYC Schools’ Electrifying Transformation

NYC Schools’ Electrifying Transformation

On October 28, 2022, New York City Mayor Eric Adams made a precedent-setting announcement, launching “Leading the Charge”, a $4 billion plan to combat climate change and create healthier learning environments, while also improving air quality and helping develop a green workforce. The centerpiece of this plan is electrification of New York City’s (NYC’s) schools. “Under this bold plan, we will not only electrify 100 schools but also ensure that we never again build a school in New York City that runs on fossil fuels,” Adams said.

This plan codifies a clean energy standard that NYC’s School Construction Authority (SCA) has been working toward fully implementing for several years. Since 2019 over two dozen of NYC’s new schools have been using fossil fuel-free equipment for their domestic hot water and cooking systems. From now on, all new schools’ heating and cooling systems will also be all-electric.

“The SCA has spearheaded the effort to reduce greenhouse emissions at our schools, becoming the first to commit to building all-electric new school buildings while working with our city partners to retrofit existing buildings,” said NYC’s SCA President and Chief Executive Officer Nina Kubota. “Thanks to the mayor’s support, we’ll continue to be at the forefront of researching, developing, and providing state-of-the-art learning facilities while combating climate change.”

The NYC SCA builds from 10 to 15 new schools each year, with an average new floor area of 1.2 million square feet, and is also in charge of all capital improvements for its 1,500 existing public schools. The SCA’s Sustainable Design and Resiliency department, which is headed up by Jeremy Shannon, is championing the agencywide effort for the design and implementation of all climate change-mitigation capital construction efforts for NYC’s public schools—both new and existing. It’s been a monumental effort to move this very large portfolio to an all-electric capacity, and this effort is one that many other school districts are watching closely.

This transition’s beginnings can be traced to 2017, when SCA initiated a multiyear study to determine how to design future new public schools to meet Passive House-level requirements. Reducing a building’s conditioning load is a critical step in transitioning to fossil fuel-free operations, and Passive House provides a clear trajectory toward that goal. The SCA assembled a team of experts to conduct the study, and this team evaluated over 75 energy conservation measures and identified 32 that were applicable to NYC school buildings. These measures ranged from additional slab insulation to gearless elevators with regenerative drives. With these 32 measures fully implemented, the resulting low-energy prototypical school building achieved an energy use intensity (EUI) of 56 kBTU/ft2/yr, even with a commercial kitchen that puts out 1,000 meals on average every school day. Excluding the commercial kitchen space, the prototypical school building achieved 36 kBTU/ft2/yr, which is lower than the Passive House requirements for school buildings.

Based on the success of this prototype design, the SCA secured supplemental funding to implement many of these measures on four pilot projects in 2019. By 2022, the pilot projects’ successes led to the study’s prototypical design measures becoming the standard of design for all new NYC public school buildings (see Table 1). Today, ten new Passive House-level schools are at various stages in the design process. “We are in the midst of our largest capital program to date—our 2020-2024 capital program—in which we are adding 60,000 seats citywide,” says Kevin Ortiz, SCA’s communication and external affairs, adding, “We are an extremely busy authority, providing the spaces that kids need to grow and learn in the type of new environments that benefit everyone.” One such space broke ground this fall in Queens.

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P.S. 85 is an overcrowded school in Astoria, Queens that is getting a new, roughly 70,000-ft2 annex that will house an additional 451 seats in classrooms designated for pre-kindergarten students through fifth grade. The annex will also house a library, a music room, a guidance and medical suite, and a gymnatorium—a combined gym and auditorium with telescopic seating. The envelope measures being incorporated into the building will make these classrooms and offices more comfortable throughout the year and a beacon of hope during extreme weather events.  All SCA projects are required to undergo climate resiliency reviews, including evaluations that rely on future flooding and heat risk maps. In speaking of the resiliency of the new standards, Dominick DeAngelis, SCA’s Vice President of Architecture and Engineering highlights, “By adding new high-performance building envelope improvements to our schools, we are gifting tangible and inspirational examples of change to the current and future generations of children while contributing to improving the climate in their lifetimes.”

SCA’s design specifications for any building are sent out for competitive bidding and must be able to be met in the conventional marketplace, which both constrains the ambitiousness of the specifications and pushes industry to meet more efficient targets than are typical. For instance, this school’s window U-factor requirements were set at 0.30 for P.S. 85, because there are American-made windows that meet that target. “The SCA is not willing to rely on performance measures that can only be met by products from European manufacturers due to supply chain concerns,” explains Shannon, adding, “This pilot helped us move to the next level, and newer schools are getting even better.” For future projects, Shannon expects the window U-factor requirement will be set at 0.2.

Electrification of schools has followed a similar path, with the SCA stepping into testing new systems incrementally so that no one school is a pilot for a total makeover. A successful multi-year test run at an earlier school paved the way for the commercial kitchen at P.S. 85 to be all electric, as will the domestic hot water and cooling systems. The all-electric kitchen likely will require some adjustments for the school’s chefs, but not having indoor combustion has big advantages in terms of indoor air quality and minimizing energy losses from the hood and exhaust system. “Now that we don’t have a combustion ventilation requirement in the kitchen space,” Shannon points out, “we were able to change the hood design and the cubic feet of airflow required, which led to energy savings that will contribute to reducing the school’s overall source EUI.”

The building’s R-30 walls will be constructed using insulated precast panels, which have been tried out already in a few other projects. Their advantage is that the panels’ concrete layer serves as an air barrier and their seams are relatively easy to seal, simplifying the achievement of the building’s ambitious targeted airtightness of 0.22 ACH50. Their disadvantage is the panels’ embodied carbon, and SCA is working to find lower carbon alternatives. Systems such as a rainscreen with a metal stud backup and other non-concrete structural systems are currently being studied and piloted as well. The school’s roof assembly will achieve an R-value of 40, thanks to being insulated with 8 inches of extruded polyiso (XPS). Other energy conservation measures being implemented include thermal bridging mitigation and lower light levels for the electrically powered lights, among others.

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All renderings courtesy of the New York City School Construction Authority.

The school’s hot water needs will be amply met by two 120-gallon heat pump water heaters.  For cooling, modulating chillers on the roof supply cooling that is distributed through the ducted ventilation system. Heating at P.S. 85 is being provided by a hot-water radiator system, with the radiators placed along the classrooms’ perimeters. The boiler supplying this system is the only fossil fuel appliance being used at this school.

The newer schools that are still in the design stage will dispense with radiators and the boilers that supply them. Instead, the heating load will be sufficiently low that it will be met by heat pumps, with the heating distributed through the ventilation system. Electric-resistance baseboard heating will be used as a back-up system should the heat pumps be out of service.

P.S. 85 is one of the first batch of newly constructed NYC schools being fitted out with a PV system—in this case a substantial 90-kW system—in accordance with NYC’s Clean Energy mandate to install 100 MW of PV on NYC’s municipally owned roofs by 2025. The overall carbon reduction for the building, even without going all electric, ended up being 50% lower than the previous already 20% better-than-code design.

The newly constructed buildings inform not only the design of subsequent schools, but also the ongoing retrofits of the 1,500-building portfolio.  Plans for two high-performance retrofits have been finalized recently and will go out for bids by early 2023. The retrofits will feature recladding of the exterior envelope, reducing thermal bridging and bringing the roof and wall R-values up to R-40 and R-30, respectively—the same performance levels that the new construction projects are targeting. And, each of these retrofit projects will include full electrification of the building systems. With these projects, SCA is aiming to standardize the requirements and material specifications for these retrofits, so that they can be rolled out without extensive analysis needed for each school building.

Because SCA’s portfolio is large, the construction and retrofits of NYC schools inevitably is priming the market for the building materials and construction approaches needed to achieve SCA’s ambitious sustainability targets. To ensure a ripple effect beyond the NYC market, all of SCA’s specs and design requirements are available online, including its comprehensive The New York City Green Schools Guide 2019.  The guide, which took a team of consultants and internal staff two years to develop, details a holistic approach to sustainable design, ensuring that these principles influence school design from the earliest stages. The document also collates all of the local, state, and national laws and LEED requirements, saving the design teams countless hours of time that would have been spent separately reporting project information based on all the different local law requirements. To further support the design teams, the guide includes templates and tools, such as:

  • energy modeling templates, schedules, and sample submissions;

  • integrated design process templates and sample submissions;

  • local law descriptions and flow charts;

  • carbon and geothermal calculators; and

  • training videos and sample submissions for each of the six phases of design and construction.

New York City, more readily recognized for its financial and cultural leadership, is now taking a leading role nationwide in school building performance. The SCA is fully on track to fulfill Mayor Adams’ pledge, thanks to the team efforts and expertise of its multidisciplinary sustainability-focused staff, and is significantly supporting the city’s commitment to reduce carbon emissions by 100% from the building sector by 2050.

Author
Mary James

Mary James

Mary James is Director of Publications at Passive House Accelerator. Her books include New York Passive House 2015; Net Zero Energy Building...

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