Welcome to our comprehensive guide on the installation and fire safety of battery energy storage systems in homes. This guide is based on the PAS 63100:2024 Electrical Installations – Protection Against Fire of Battery Energy Storage Systems for Use in Dwellings – Specification, issued by the Department for Energy Security & Net Zero. This Publicly Available Specification (PAS) was sponsored by the Department for Energy Security and Net Zero, facilitated by BSI Standards Limited, and published under licence from The British Standards Institution. It came into effect on 31 March 2024.
Electrical Energy Storage and Renewable Energy
Electrical energy storage, particularly in the form of batteries, is a crucial component of renewable energy strategies. With their ability to enhance the efficiency of renewable technologies like solar photovoltaic (PV) systems, electrical energy storage systems (EESSs) offer significant benefits to consumers and electricity providers. As such, a substantial increase in the installation of EESSs is anticipated.
Fire Safety and Battery Storage
This article aims to guide installers on managing fire safety hazards associated with EESSs in UK homes. The goal is to minimise the risk of batteries becoming an ignition source and to mitigate the effects of a battery fire, should one occur.
Best Practices for Battery Location
The ideal location for storage batteries is outside dwellings and away from rooms used for living. If outdoor placement is not feasible, there are basic requirements for indoor locations housing storage batteries. These include:
- Ensuring batteries are separated from habitable rooms and escape routes by appropriate fire compartmentation.
- Providing fire detection for the battery location, linked to a fire alarm system to alert inhabitants of a fire.
- Making sure that inhabitants’ escape routes are not obstructed.
Battery Fires and Fire Compartmentation
While battery fires are currently infrequent, they can have severe consequences due to the nature of battery fire behaviour. Some batteries can produce focused, jet-like flames, necessitating a higher degree of fire compartmentation. Future editions of this standard may need to reassess fire compartmentation requirements due to existing gaps in understanding how fire compartmentation withstands lithium battery fires.
Regulations and Standards
This specification assumes that competent persons for electrical energy storage systems are defined according to the Building Regulations Approved Documents of England or the relevant national equivalents in Wales, Scotland, and Northern Ireland.
The NFPA 855, a document from the United States National Fire Protection Association, was used as a reference in developing requirements for storage battery installation locations and determining maximum stored energy values.
In conclusion, proper installation and management of battery storage are crucial for maximising the benefits of renewable energy systems while ensuring safety in residential settings.
Protection Against Fire
When it comes to installing storage batteries, the first preference is to install them outdoors. However, if outdoor installation is not feasible, indoor installation is permissible under certain conditions:
- The location should not be precluded by section 6.5.5.
- The location should have ventilation as per section 6.5.4.
- The location should have fire-resisting separation as required by section 6.5.3.
Outdoor installation can include an outbuilding not intended for habitation, detached or separated by a main wall with a minimum fire performance of REI 120 to BS EN 13501.
If a battery energy storage system (BESS) is installed on the external wall of a building, it should not compromise the fire performance of the external wall. Service penetrations should be adequately fire-stopped, and internal combustible substrates should not be exposed by the installation. If wall cavities exist, cavity barriers should be provided for services passing through the wall.
Any indoor location housing storage batteries or their enclosures should have fire-resisting separation from locations identified in section 6.5.5. This separation should be provided by walls, ceilings, and floors with a fire performance of at least REI 30 to BS EN 13501 series (or 30 min to BS 476 series for load-bearing capacity, integrity, and insulation).
All indoor locations containing storage batteries should have fresh-air ventilation to the outdoors. The ventilation system should not compromise the fire resistance of the enclosure. The edges of the outdoor port for such ventilation should be at least 1 m from the edges of doors, windows, or ventilation ports for other locations.
Batteries should not be installed in any of the following locations:
- Rooms intended for sleeping.
- Routes used as a means of escape that are not defined as protected escape routes, including landings, staircases, and corridors.
- Corridors, shafts, stairs, or lobbies of protected escape routes.
- Firefighting lobbies, shafts, or staircases.
- Storage cupboards, enclosures, or spaces opening into rooms intended for sleeping.
- Outdoors (ground-mounted or wall-mounted in a suitable enclosure) within 1 m of escape routes, doors, windows, or ventilation ports.
- Voids, roof spaces, or lofts.
- Within 2 m of stored flammable materials and fuel storage tanks or cylinders.
- Cellars or basements that have no access to the outside of the building.
This guidance is based on current knowledge and may need to be reassessed in future editions of the standard, particularly regarding fire compartmentation requirements and how they resist lithium battery fires. It also takes into account air tightness requirements for dwellings and planning consent or notification requirements for equipment mounted on an external wall.
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