February 7, 2023

New Residential Energy Storage Code Requirements

Find out about options for residential energy storage system siting, size limits, fire detection options, and vehicle impact protections.
installation of smoke detector

At SEAC’s Jan. 26, 2023 general meeting, Storage Fire Detection working group vice chair Jeff Spies presented on code-compliance challenges and potential solutions for residential energy storage systems (ESS).

This post covers system design and permitting considerations based on the latest editions of the International Fire Code (IFC) and the International Residential Code (IRC) including:

  • ESS siting and size limits
  • Fire detection options, including siting ESS in an attached garage
  • Vehicle impact protection

Siting and Size Limits

You have four options for siting ESS in a residential setting: an enclosed utility closet, basement, storage or utility space within a dwelling unit with finished or noncombustible walls or ceilings; inside a garage or accessory structure; on the exterior wall of the home; and on ground mounts.

Inside dwelling units, ESS shall not be installed in sleeping rooms, or closets or spaces opening directly into sleeping rooms or in habitable spaces of dwelling units. Systems in these locations are also limited to 40 kilowatt-hours (kWh) of storage capacity.

In all other locations noted above, the size limit is 80 kWh.

On the exterior walls of the home, it’s important to note that systems cannot go within 3 feet of doors or windows leading directly into the home.

And as we will soon discuss, code compliance for ESS in an attached garage can be much more complicated than systems in a detached garage.

The California State Fire Marshal has stated in an information bulletin that the locations can be combined for a cumulative total of 280 kWh of ESS capacity.

Fire Detection

SEAC’s Storage Fire Detection working group strives to clarify the fire detection requirements in the International Codes (I-Codes).

The 2021 IRC calls for the installation of heat detectors that are interconnected to smoke alarms. The problem is detectors and alarms are different systems that cannot be interconnected with one another.

Heat alarms have an onboard annunciator with a bell, a light, or some other warning signal, and battery backup. Heat detectors are designed to work with Fire Alarm Control Panels (FACP) and whole home fire and alarms systems. These systems typically have a central annunciator and battery backup for the FACP.

Per the California Office of the State Fire Marshal, you can use a smoke alarm to comply with the code, but only within conditioned space. The utility room inside the dwelling area might be air conditioned. How about a garage attached to the home? If the garage is not air conditioned, you cannot use a smoke alarm there as smoke alarms will not work reliably or properly in unconditioned spaces.

Unlike heat detectors, heat alarms can be interconnected with smoke alarms. As of January 2023, however, Spies said there are no heat alarms that are listed for use in unconditioned spaces as the UL 539 standard for heat alarms only recently introduced a “non conditioned” space test for heat alarms.

As of this time, there are no products that have completed this test to get this listing. Spies said he believes some manufacturers are going through the listing process. But it is unclear when a listed product might be commercially available.

So what can you do?

One option is to avoid installing ESS in attached garages and put them somewhere else.

Another option is to use a heat alarm and ask the local authority having jurisdiction for a permit based on alternative means of compliance. In 2021, the California State Fire Marshall issued an information bulletin that points out confusion in the code and says the term heat alarm may be more appropriate than heat detector.

Spies named three heat alarm-and-detector solutions that might be permitted in some jurisdictions:

Use of the First Alert heat alarm is limited to spaces with a maximum ambient temperature of 115°F. In Southern California, safety officials may not approve this device, because the temperature inside a garage can exceed the limit.

The System Sensor 5600 Series device, when combined with an FACP or with a System Sensor P2RHK-120 Horn/Strobe, may be deemed sufficient to meet the intent of the code by AHJs.

Because the Resideo heat alarm is wireless, it has the advantage of a simple, low-cost installation. But Spies said the device was brought to his attention only about a month ago and may not yet be available for purchase yet.

Kevin Reinertson, deputy fire marshall in Riverside County, California, noted there is another option that may be approved by California AHJs for newer one- and two-family dwellings with fire sprinklers in the garage. In those homes, you may be permitted to use a flow switch and interconnect a heat detector with the sprinkler system to achieve code compliance. 

It is strongly advised you check with your local building or fire authority having jurisdiction to see if the options above may be acceptable for compliance.

Vehicle Impact Protection

The IFC requires bollards or curb stops for ESS that are subject to vehicular impact damage. See the image below for garage areas that are not subject to damage and don’t require bollards or curb stops.

For more details about code compliance for vehicle impact protection, including important safety considerations for cutting or drilling into concrete that may have post tension concrete slab construction with high-tension cables, see the presentation slides shared at SEAC’s January general meeting.

Spies developed the presentation with Storage Fire Detection working group chair Mark Rodriguez, Vehicle Impact Protection working group vice chair Ben Davis, and the CEO of Mayfield Renewables Ryan Mayfield. The group first delivered the presentation at a California Solar and Storage Association (CALSSA) webinar.

Join the Storage Fire Detection Working Group

The Storage Fire Detection working group develops recommendations for how AHJs and installers can handle ESS in residential settings in spite of the confusion in the International Codes. The group also leads efforts to clarify the fire protection requirements in future code cycles.

Code change proposals for NFPA 855, the Standard for the Installation of Stationary Energy Storage Systems, are due June 1. In the months ahead, the working group will discuss proposals addressing fire protection for residential ESS. SEAC working groups are open to all. To get involved, fill in the contact form at the bottom of the SEAC homepage, and note in the comments that you would like to join the Storage Fire Detection working group.