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Published on October 23, 2025iBuilding Management,Climate Change & Resiliency,NYC Environmental Issues,Renewable Energy
The New York City Department of Buildings (NYCDOB) recently adopted two new rules mandating the safe design, installation, operation and maintenance, and decommissioning of energy storage systems (ESS), including indoor systems that were not previously regulated by the NYC Fire Department (FDNY). This SPR Blog post presents key highlights from the new NYCDOB rules, which will become effective on October 26, 2025.
New Section 101-19 Adopting National Uniform Safety Standards for ESS
The first NYCDOB rule establishes a new Section 101-19 in Subchapter A of Chapter 100 of Title 1 of the Rules of the City of New York (RCNY), which sets forth comprehensive requirements for ESS design, commissioning, operation and maintenance, decommissioning, and reporting. Notably, the new Section 101-19 will enable the indoor installation of ESS within NYC buildings by adopting certain national uniform safety standards to minimize the risk for ESS accidents and failures including fires. These standards include a modified National Fire Protection Association (NFPA) 855 – Standard for the Installation of Stationary Energy Storage Systems (2020 edition as modified by NYCDOB, the "Modified NFPA 855"), Underwriters Laboratories (UL) 9540 – Safety of Energy Storage Systems and Equipment (February 2020 edition as revised April 2021), and UL 9540A – Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems (November 2019 edition). All ESS installations must be properly commissioned, tested, and maintained in compliance with these standards as adopted by NYCDOB.
Section 101-19 will apply to the following categories of ESS: (i) indoor ESS installations exceeding the Modified NFPA 855's minimum aggregate capacities set forth in Table 1.3 of Section 3616-07; (ii) outdoor ESS installations exceeding the minimum aggregate capacities established in the FDNY rules regulating outdoor ESS installations; and (iii) all indoor and outdoor ESS installations associated with one- and two-family dwellings. At the request of FDNY, the minimum aggregate capacity thresholds for lithium-ion and other battery technologies in Table 1.3 were modified from higher threshold values found in the unmodified NFPA 855 standard to 1 kilowatt-hour (kWh) in the NYCDOB-adopted Modified NFPA 855 standard to reflect the potential hazards of these smaller systems and align with anticipated changes to the Fire Code.
ESS Permitting, Certification, and Registration Requirements
All ESS-related construction documents must be approved by NYCDOB in advance of system installation. The necessary construction documents include technical ESS design plans and specifications per the Modified NFPA 855 standard, a zoning compliance analysis (except for certain accessory indoor ESS installations), a firefighting access plan for proposed rooftop or site-specific installations of ESS, and evidence of flood-resistant construction per the NYC Building Code. Most types of ESS installations are considered site-specific installations under Section 101-19, and proposals for such site-specific ESS installations should be peer-reviewed by New York State-licensed engineers who have relevant ESS and fire protection engineering experience and are independent from the design professional of record to verify their compliance with applicable NYC Construction Codes, Electrical Code, Fire Code, and FDNY rules and the Modified NFPA 855, UL 9540, and UL 9540A standards. Then, upon a satisfactory demonstration of compliance in a peer review report, the NYCDOB's Office of Technical Certification and Research (OTCR) would issue a "conditional acceptance letter" for the site-specific ESS installation required to obtain NYCDOB permits for construction and electrical work. However, ESS installations associated with one- and two-family dwellings that comply with Modified NFPA 855 and have received a FDNY Certificate of Approval do not require site-specific review and approval by the OTCR; the OTCR may also waive the site-specific review requirement for other types of ESS that have received a FDNY Certificate of Approval, at the OTCR's discretion.
Following installation and inspection of the ESS, a registered design professional should certify the new system's compliance with OTCR's conditional acceptance letter, then the OTCR will issue a "final acceptance letter" and NYCDOB will issue a "letter of completion" to demonstrate the agency's final approval of the ESS. However, for any site where a new ESS use is non-accessory to the principal use of the zoning lot, NYCDOB will instead issue a new certificate of occupancy to reflect the new zoning use group of the non-accessory ESS. Operation of a newly constructed ESS is prohibited until a letter of completion (or certificate of occupancy, if applicable) has been issued by the NYCDOB. Most new ESS should be registered with NYCDOB before commencing operation, and existing systems are generally required to register with the NYCDOB by October 2028. The proposed decommissioning of an ESS will also require advance notification to NYCDOB.
Modified NFPA 855 Standard Adopted in Section 3616-07
The second NYCDOB rule adds a new Section 3616-07 to Chapter 3600 of Title 1 of the RCNY, which aims to improve the safety of ESS installations and the storage of lithium metal and lithium-ion batteries by adopting the Modified NFPA 855 that has been aligned with the NYC Fire Code. This Modified NFPA 855 standard establishes certain restrictions on ESS siting, such as minimum separation distances to reduce the potential spreading of fires, and requires fire detection and suppression systems to mitigate hazards, emergency response plans prepared in advance of ESS commissioning, and hazard mitigation analyses such as fire and deflagration testing. The new Section 3616-07 also emphasizes the importance of adequate personnel training and detailed commissioning/decommissioning procedures.
The plans and specifications for a proposed ESS installation or retrofit must be submitted to the NYCDOB and/or FDNY for approval, depending on whether the ESS will be located indoors or outdoors. An operations and maintenance manual should be prepared in advance of NYCDOB's final approval of the ESS installation and kept readily accessible to responsible personnel. The owner, manufacturer and/or installer are required to develop an emergency management plan that establishes the parties' respective emergency response obligations prior to commissioning of the ESS, and the owner should also develop a pre-incident plan to coordinate their own responses to potential emergencies consistently with such broader emergency management plan.
Commissioning reports by qualified personnel should be submitted to NYCDOB and FDNY for final approval of the ESS installation, and a copy of the report should be retained by responsible personnel. A decommissioning plan detailing the means and methods for decommissioning the ESS also must be prepared ahead of any decommissioning activities, and once decommissioning is complete, a decommissioning report must be prepared and supplied to NYCDOB upon request.
Fire Hazard Testing and Mitigation Requirements for Indoor ESS Installations
Large-scale fire testing under UL 9540A will be required for most ESS installations, except for certain lead-acid and nickel-cadmium batteries used in limited standby or emergency applications. Indoor ESS installations are required to include explosion prevention per NFPA 69 – Standard on Explosion Prevention Systems, or deflagration venting per NFPA 68 – Standard on Explosion Protection by Deflagration Venting, unless large-scale fire testing results demonstrating minimal flammable gas risk are approved by NYCDOB. Sites with non-mechanical ESS generally require permanent water sources for fire protection and a method of neutralizing potential ESS electrolyte spills.
The installation of ESS indoors will generally only be permitted in buildings that are fully protected by a sprinkler system, and the ESS control areas should have a sprinkler system designed in accordance with NFPA 15 – Standard for Water Spray Fixed Systems for Fire Protection. Most indoor ESS are prohibited from being installed below-grade, unless otherwise approved by FDNY, or below the design flood elevation established in Appendix G of the NYC Building Code.
Where an ESS is installed within a building containing other kinds of uses, the specific rooms exclusively dedicated to housing the ESS must be separated from all other building spaces and uses, and only authorized ESS workers are permitted to occupy such dedicated ESS rooms. In buildings containing ESS that also have fire alarm systems, the main fire alarm control panel should include signage or other documentation identifying the location, capacity, and type of ESS installed within the building, among other critical firefighting information.
Dedicated-use ESS buildings will be considered indoor ESS systems under the NYCDOB rule. Occupants of the rooms containing ESS are restricted to authorized ESS workers, and no other types of building occupancy except for the ESS will be permitted in such a dedicated-use ESS building.
ESS installations associated with one- and two-family dwellings must comply with the provisions of new Section 3616-07 and the NYC Fire Code. Permissible ESS installation locations for one- and two-family dwellings include: on the walls or floors of attached garages that are separated from the dwelling by minimum one- or two-hour fire-rated barriers, depending on size of the system; on the walls or floors of detached garages; on a non-combustible exterior wall and at least three feet away from doors and windows; or on the ground within three feet from a non-combustible exterior wall and at least three feet away from doors and windows. Inpidual ESS units must be located at least three feet apart, unless otherwise approved by NYCDOB and/or FDNY based on large-scale fire testing results. Critically, ESS may not be installed in the living area of dwelling units or in any sleeping units.
Outdoor ESS installations, including rooftop and open parking garage installations, should continue to comply with the relevant FDNY rules regulating outdoor systems.
In summary, the NYCDOB's recently adopted rules will establish rigorous, nationally aligned safety and operational standards for ESS covering all stages from design and approval through operation and decommissioning, with specific provisions tailored for residential and commercial settings within NYC's densely urban environment. These new ESS rules present a significant opportunity for NYC building owners to facilitate the electrification of their buildings and support decarbonization efforts under state and local emissions reduction laws.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
