Enforcement of the New York City Energy Conservation Code begins March 30, requiring new construction and major renovations to meet the new codes before certificates of occupancy are granted. The code now requires air duct leakage testing, backup electric heating to support resilience during extreme weather and participation in demand response programs to help maximize electricity use efficiency, among other things.
With compliance now required, there are two pathways for building operators to proceed: one prescriptive and the other performance-based, according to Drew Maggio, technical director at Highmark, a company providing building decarbonization, electrification and energy efficiency technologies in New York City.
“Prescriptive is essentially you check all these boxes, and make sure you’re following all these rules, then you’re good to go,” Maggio said in an interview. Performance-based compliance requires owners to comply with the city’s version of ASHRAE 90.1, the Energy Standard for Buildings Except Low-Rise Residential Buildings.
Adopted in January, the 2025 NYCECC has significant changes from the 2020 prescriptive pathway, according to Maggio. While the previous version only required operators to meet one of eight energy efficiency options, the new pathway follows a point system, similar to those of LEED and WELL. That provides flexibility in how operators can earn credits to become compliant, Maggio said.
With the new version, “there are 35 different credits that you can possibly pick up, and then, based on your building size, your occupancy rates, the zoning of the building, [etc.], it essentially gives you a minimum required score,” Maggio said. “Then you get to pick and choose through those 35 options.”
Due to the large number of options under the prescriptive pathway and the soft costs like engineering and consulting fees associated with an upgrade or new construction project, it might be easier to go on the performance path, Maggio said.
Some clients Maggio has worked with have started with a prescriptive pathway, and then when modifications are requested by the owners, like a giant window or single-layer glass that won’t help check off boxes for the prescriptive-pathway, they have pivoted to the performance pathway.
“They’re going to stick with the prescriptive pathway and then move to performance if they have to,” Maggio said. “Anything [with] over 40% glazing or 40% windows on the exterior of the building, they’re going to have to go performance-based. It’s not that using that much glazing is necessarily bad for the building, but you’re not going to [check] all those boxes.”
Another large change is that, for the 2025 NYCECC performance pathway, your baseline building performance assumes 100% resistive heat. Because ASHRAE 90.1 does not provide a way to assess the energy efficiency of domestic hot water systems, the implementation of heat pumps can provide more than 100% efficiency over the baseline requirements. Now, any benefits from using a heat pump system over that resistive heating baseline are going to help pick up efficiency in the performance pathway, Maggio said
“That's something that will hopefully drive the market toward using heat pumps more,” Maggio said. “The engineers and the designers that are putting these systems together are going to realize those benefits when it comes to code compliance.”
Ultra-low-energy building projects will also be affected. While zoning regulations offer developers an additional 5% floor-area-ratio if they exceed the NYCECC code by 15%, the stricter codes being implemented will make hitting that target harder, “but not impossible,” Maggio said.
Building envelope tightness values, or thermal R-values and U-values, haven’t changed much besides becoming a little bit more stringent. But other envelope changes could more significantly impact projects, according to Maggio. Thermal bridge mitigation, or insulating the outside of a building from the structural components on the inside of the building, was not technically required but now involves more documentation, he said.
“When I talk about that prescribed-compliance pathway, there’s a line that basically says, ‘If you have a thermal bridge that’s going to cause your building to lose this much heat or impact your efficiency by this much, you now have to use thermal bridging mitigation measure at that joint,’” Maggio said.
Perhaps most importantly, operators designing renovations and new construction must also now meet air tightness requirements. Not only did the flow rate targets change — going from 0.4 cubic feet per minute of air flow per square foot of building to 0.35 — the new code also mandates air-leak testing.
“They’re looking at it from the perspective of, if you have a leaky building, electrifying that building is going to be so much worse,” Maggio said. “There are all these downstream effects of having a poor building envelope. First of all, it’s going to place more draw on the power systems … Additionally, when you go to electrify and use these heat pump systems, it’s not just adding another five feet onto the end of your boiler. You might need to add another two or three heat pump modules.”
Although these tests will bear costs, especially in New York City, the benefit of a tighter building envelope should significantly offset equipment and energy costs moving forward, Maggio said.
